Multitech ProxyServer MTPSR3-200 User Manual

Model MTPSR3-200

ProxyServer User Guide

User Guide

88301202 Revision C

ProxyServer 200-Series (Model No MTPSR3-200)

This publication may not be reproduced, in whole or in part, without prior expressed written permission from
Multi-Tech Systems, Inc. All rights reserved. Copyright© 1998, by Multi-Tech Systems, Inc. Multi-Tech
Systems, Inc. makes no representations or warranties with respect to the contents hereof and specifically
disclaims any implied warranties of merchantability or fitness for any particular purpose. Furthermore, Multi­Tech Systems, Inc. reserves the right to revise this publication and to make changes from time to time in the
content hereof without obligation of Multi-Tech Systems, Inc. to notify any person or organization of such
revisions or changes.

Record of Revisions

Revision Description
A Manual released. All pages at revision A.

(1 1/20/97)
B Manual revised. All pages at revision B.

(1/9/98)
C Manual revised. All pages at revision C.

(4/3/98)

Patents

This Product is covered by one or more of the following U.S. Patent Numbers: 5.301.274; 5.309.562;

5.355.365; 5.355.653; 5.452.289; 5.453.986. Other Patents Pending.

TRADEMARK

The Multi-Tech logo is a trademark of Multi-Tech Systems, Inc.
Windows is a registered trademark of Microsoft.

Multi-Tech Systems, Inc.

2205 Woodale Drive

Mounds View , Minnesota 55112

[phone] or [phone]

Fax [phone]

Tech Support [phone]

BBS [phone] or [phone]

Internet Address: http://www.multitech.com

Fax-Back [phone]

Contents

Chapter 1 - Introduction and Description

Introduction .......................................................................................................................................................6

Preview of this Guide ........................................................................................................................................6

Chapter 1 - Introduction and Description ....................................................................................................6

Chapter 2 - Installation................................................................................................................................6

Chapter 3 - Software Loading and Configuration........................................................................................6

Chapter 4 - ProxyServer Software..............................................................................................................7

Chapter 5 - Remote Configuration ..............................................................................................................7

Chapter 6 - Router Management ................................................................................................................7

Chapter 7 - Service, Warranty and Tech Support .......................................................................................7

TCP/IP (Transmission Control Protocol/Internet Protocol)................................................................................8

Internet Protocol (IP) .......................................................................................................................................10

Front Panel...................................................................................................................................................... 11

Back Panel ......................................................................................................................................................12

Link 1 (2 and 3) Connector .......................................................................................................................12

EtherNet 10Base-T Connector..................................................................................................................12

EtherNet 10Base-2 Connector.................................................................................................................. 12

Command Connector................................................................................................................................ 12

Power Connector ...................................................................................................................................... 12

Applications.....................................................................................................................................................12

Specifications ..................................................................................................................................................13

EtherNet Port ............................................................................................................................................13

Command Port..........................................................................................................................................13

WAN Links ................................................................................................................................................13

Electrical/Physical.....................................................................................................................................13

Requirement .............................................................................................................................................13

Chapter 2 - Installation

Introduction .....................................................................................................................................................16

Unpacking .......................................................................................................................................................16

Installation .......................................................................................................................................................17

Adding Additional RAM....................................................................................................................................18

Chapter 3 - Software Loading and Configuration

Introduction .....................................................................................................................................................20

Loading your Software ....................................................................................................................................20

Chapter 4 - ProxyServer Software

Introduction .....................................................................................................................................................24

Before Y ou Begin......................................................................................................................................24

Setup Menu.....................................................................................................................................................25

Setting up your IP Address..............................................................................................................................26

Selecting your WAN Protocol..........................................................................................................................27

Activating your WAN Ports..............................................................................................................................28

Scripting....................................................................................................................................................28

Changing Proxy Applications...........................................................................................................................29

Adding Client IP Addresses for the DHCP Server...........................................................................................29

Enabling Remote Servers ...............................................................................................................................30

WEB Server..................................................................................................................... ......................... 30

Running Diagnostics ....................................................................................................................................... 32

Chapter 5 - Remote Configuration

Introduction .....................................................................................................................................................34

Modem-Based Remote Configuration Procedure............................................................................................34

LAN-Based Remote Configuration ..................................................................................................................37

Windows Sockets Compliant TCP/IP Stack..............................................................................................37

Chapter 6 - Router Management

Introduction .....................................................................................................................................................40

Proxy Server Management Menu....................................................................................................................40

Proxy Server Configuration .............................................................................................................................41

Applications .............................................................................................................................................. 41

Chapter 7 - Service, Warranty and Tech Support

Introduction .....................................................................................................................................................44

Limited Warranty .............................................................................................................................................44

Tech Support ................................................................................................................................................... 45

Recording ProxyServer Information..........................................................................................................45

Service ............................................................................................................................................................ 46

About the Multi-Tech BBS ...............................................................................................................................47

Logging on to the Multi-Tech BBS............................................................................................................. 47

Downloading a File ...................................................................................................................................47

Reading a Message ..................................................................................................................................48

Leaving a Message...................................................................................................................................48

Bulletins ....................................................................................................................................................48

About CompuServe.........................................................................................................................................48

About the Internet............................................................................................................................................ 48

About the Multi-Tech Fax-Back Service ..........................................................................................................49

Appendices

Appendix A - Cabling Diagrams.......................................................................................................................52

Appendix B - Script Language.........................................................................................................................53

Appendix C - Regulatory Information ..............................................................................................................55

Glossary of Terms.............................................................................................................................59

Chapter 1 - Introduction and

Description

ProxyServer User Guide

Introduction

Welcome to Multi-Tech’s new ProxyServer™, model number MTPSR3-200, a single, secure gateway

that provides multiple LAN users with high performance Internet access. The ProxyServer functions

as a TCP/IP proxy server that resides on the outer edge of your firewall and provides up to 168K of

bandwidth to LAN users. The ProxyServer 200-Series features a 10BaseT or AUI port for local LAN

connection, Command Port for configuration, and three internal K56flexTM modems* with Multilink

Point-to-Point Protocol (MLPPP) allowing for a bandwidth up to 168K bps. System management is

provided through the command port using bundled Windows® software which provides easy-to-use

configuration menus.

Note: Though these modems are cabable of 56K bps download performance, line impairments,

public telephone infrastructure and other external technological factors currently prevent maximum

56K bps connections.

Figure 1-1. ProxyServer

Preview of this Guide

This guide describes the ProxyServer and tells you how to install and configure the unit. The

information contained in each chapter is as follows:

Chapter 1 - Introduction and Description

Chapter 1 describes the ProxyServer 200-Series Proxy Server. A description of the Transmission

Control Protocol/Internet Protocol (TCP/IP) and Internet Protcol (IP), front panel indicators, back

panel connectors are provided. A list of relevant specifications is provided at the end of the chapter.

Chapter 2 - Installation

This chapter provides information on unpacking and cabling your ProxyServer. The installation

procedure describes each cable connection starting with connecting the power cord, command port,

LAN and finally the WAN.

Chapter 3 - Software Loading and Configuration

Chapter 3 details the software loading which configures the IP port and default WAN links. The

ProxyServer software diskettes are Windows® based. Each field within a dialog box that is alterable is

described.

* Though this modem is capable of 56K bps download performance, line impairments, public

telephone infrastructure and other external technological factors currently prevent maximum 56K
bps connections.

6

MTPSR3-200

Chapter 1 - Introduction and Description

Chapter 4 - ProxyServer Software

Chapter 4 describes the ProxyServer 200-Series Proxy Server software package designed for the
Windows ® environment. The Proxy Server Program Group has five icons that allow for Proxy Server
configuration, download default setup, download firmware update, Configuration port setup, and WAN
device configuration from the program manager. Each field within a dialog box is explained in detail
and when fields relate to each other, that relationship is explained.

Chapter 5 - Remote Configuration

This chapter provides procedures for changing the configuration of a remote ProxyServer. Remote
configuration allows you to change the configuration of a unit by simply connecting two modems
between the two ProxyServers and remotely controlling the unit.

Chapter 6 - Router Management

Chapter 6 describes a typical Telnet Client applications (i.e., proxy server and WAN device
configurations).

Chapter 7 - Service, Warranty and Tech Support

Chapter 7 provides instructions on getting service for your ProxyServer at the factory , a statement of
the limited warranty , information about our user bulletin board service, and space for recording
information about your ProxyServer prior to calling Multi-Tech’s Technical Support.

MTPSR3-200

7

ProxyServer User Guide

TCP/IP (Transmission Control Protocol/Internet Protocol)

TCP/IP is a protocol suite and related applications developed for the U.S. Department of Defense in

the 1970s and 1980s specifically to permit different types of computers to communicate and

exchange information with one another. TCP/IP is currently mandated as an of ficial U.S. Department

of Defense protocol and is also widely used in the UNIX community .

Before you install TCP/IP on your network, you need to establish your Internet addressing strategy.

First, choose a domain name for your company . A domain name is the unique Internet name, usually

the name of your business, that identifies your company. For example, Multi-Tech’ s domain name is

multitech.com (where .com indicates this is a commercial organization; .edu denotes educational

organizations, .gov denotes government organizations). Next, determine how many IP addresses

you’ll need. This depends on how many individual network segments you have, and how many

systems on each segment need to be connected to the Internet. You’ll need an IP address for each

network interface on each computer and hardware device.

IP addresses are 32 bits long and come in two types: network and host. Network addresses come in

five classes: A, B, C, D, and E. Each class of network address is allocated a certain number of host

addresses. For example, a class B network can have a maximum of 65,534 hosts, while a class C

network can have only 254. The class A and B addresses have been exhausted, and the class D and

E addresses are reserved for special use. Consequently , companies now seeking an Internet

connection are limited to class C addresses.

Early IP implementations ran on hosts commonly interconnected by Ethernet local area networks

(LAN). Every transmission on the LAN contains the local network, or medium access control (MAC),

address of the source and destination nodes. The MAC address is 48-bits in length and is non-

hierarchical; MAC addresses are never the same as IP addresses.

When a host needs to send a datagram to another host on the same network, the sending application

must know both the IP and MAC addresses of the intended receiver . Unfortunately, the IP process

may not know the MAC address of the receiver. The Address Resolution Protocol (ARP), described

in RFC 826 (located at ftp://ds.internic.net/rfc/rfc826.txt) provides a mechanism for a host to

determine a receiver’s MAC address from the IP address. In the process, the host sends an ARP

packet in a frame containing the MAC broadcast address; and then the ARP request advertises the

destination IP address and asks for the associated MAC address. The station on the LAN that

recognizes its own IP address will send an ARP response with its own MAC address. An ARP

message is carried directly in an IP datagram.

Other address resolution procedures have also been defined, including those which allow a diskless

processor to determine its IP address from its MAC address (Reverse ARP, or RARP), provides a

mapping between an IP address and a frame relay virtual circuit identifier (Inverse ARP, or InARP),

and provides a mapping between an IP address and ATM virtual path/channel identifiers (ATMARP).

The TCP/IP protocol suite comprises two protocols that correspond roughly to the OSI Transport and

Session Layers; these protocols are called the Transmission Control Protocol and the User Datagram

Protocol (UDP). Individual applications are referred to by a port identifier in TCP/UDP messages.

The port identifier and IP address together form a “socket”. Well-known port numbers on the server

side of a connection include 20 (FTP data transfer), 21 (FTP control), 23 (Telnet), 25 (SMTP), 43

(whois), 70 (Gopher), 79 (finger), and 80 (HTTP).

TCP, described in RFC 793 ( ftp://ds.internic.net/rfc/rfc793.txt) provides a virtual circuit (connection-

oriented) communication service across the network. TCP includes rules for formatting messages,

establishing and terminating virtual circuits, sequencing, flow control, and error correction. Most of

the applications in the TCP/IP suite operate over the “reliable” transport service provided by TCP.

UDP, described in RFC 768 (ftp://ds.internic.net/rfc/rfc768.txt) provides an end-to-end datagram

(connectionless) service. Some applications, such as those that involve a simple query and

response, are better suited to the datagram service of UDP because there is no time lost to virtual

circuit establishment and termination. UDP’s primary function is to add a port number to the IP

address to provide a socket for the application.

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MTPSR3-200

Chapter 1 - Introduction and Description

The Application Layer protocols are examples of common TCP/IP applications and utilities, which
include:

• T elnet (Telecommunication Network): a virtual terminal protocol allowing a user logged on to
one TCP/IP host to access other hosts on the network, described in RFC 854 ( ftp://
ds.internic.net/rfc/rfc854.txt).

• FTP: the File Transfer Protocol allows a user to transfer files between local and remote host
computers per IETF RFC 959 ( ftp://ds.internic.net/rfc/rfc959.txt).

• Archie: a utility that allows a user to search all registered anonymous FTP sites for files on a
specified topic.

• Gopher: a tool that allows users to search through data repositories using a menu-driven,
hierarchical interface, with links to other sites, per RFC 1436 ( ftp://ds.internic.net/rfc/
rfc1436.txt).

• SMTP: the Simple Mail Transfer Protocol is the standard protocol for the exchange of
electronic mail over the Internet, per IETF RFC 821 ( ftp://ds.internic.net/rfc/rfc821.txt).

• HTTP: the Hypertext Transfer Protocol is the basis for exchange of information over the
World Wide Web (WWW). Various versions of HTTP are in use over the Internet, with HTTP
version 1.0 (per RFC 1945) ( ftp://ds.internic.net/rfc/rfc1945.txt) being the most current.

• HTML: WWW pages are written in the Hypertext Markup Language (HTML), an ASCII-based,
platform-independent formatting language, per IETF RFC 1866 ( ftp://ds.internic.net/rfc/
rfc1866.txt).

• Finger: used to determine the status of other hosts and/or users, per IETF RFC 1288 ( ftp://
ds.internic.net/rfc/rfc1288.txt).

• POP: the Post Office Protocol defines a simple interface between a user’s mail reader
software and an electronic mail server; the current version is POP3, described in IETF RFC
1460 ( ftp://ds.internic.net/rfc/rfc1460.txt).

• DNS: the Domain Name System defines the structure of Internet names and their association
with IP addresses, as well as the association of mail, name, and other servers with domains.

• SNMP: the Simple Network Management Protocol defines procedures and management
information databases for managing TCP/IP-based network devices. SNMP, defined by RFC
1 157 ( ftp://ds.internic.net/rfc/rfc1157.txt) is widely deployed in local and wide area network.
SNMP V ersion 2 (SNMPv2), per RFC 1441< ftp://ds.internic.net/rfc/rfc1441.txt) adds security
mechanisms that are missing in SNMP, but is also more complex.

• Ping: a utility that allows a user at one system to determine the status of other hosts and the
latency in getting a message to that host. Ping uses ICMP Echo messages.

• Whois/NICNAME: Utilities that search databases for information about Internet domain and
domain contact information, per RFC 954 ( ftp://ds.internic.net/rfc/rfc954.txt).

• Traceroute: a tool that displays the route that packets will take when traveling to a remote
host.

MTPSR3-200

9

ProxyServer User Guide

Internet Protocol (IP)

IP is the Internet standard protocol that tracks Internetwork node addresses, routes outgoing
messages and recognizes incoming messages, allowing a message to cross multiple networks on
the way to its final destination. The IPv6 Control Protocol (IPV6CP) is responsible for configuring,
enabling, and disabling the IPv6 protocol modules on both ends of the point-to-point link. IPV6CP
uses the same packet exchange mechanism as the Link Control Protocol (LCP). IPV6CP packets are
not exchanged until PPP has reached the Network-Layer Protocol phase. IPV6CP packets received
before this phase is reached are silently discarded. (See also TCP/IP.)

Before you install TCP/IP on your network, you need to establish your Internet addressing strategy.
You first choose a domain name for your company. A domain name is the unique Internet name,
usually the name of your business, that identifies your company . For example, Multi-Tech’s domain
name is multitech.com (where .com indicates this is a commercial organization; .edu denotes
educational organizations, .gov denotes government organizations). Next, you determine how many
IP addresses you’ll need. This depends on how many individual network segments you have, and
how many systems on each segment need to be connected to the Internet. You need an IP address
for each network interface on each computer and hardware device.

IP addresses are 32 bits long and come in two types: network and host. Network addresses come in
five classes: A, B, C, D, and E. Each class of network address is allocated a certain number of host
addresses. For example, a class B network can have a maximum of 65,534 hosts, while a class C
network can have only 254. The class A and B addresses have been exhausted, and the class D and
E addresses are reserved for special use. Consequently , companies now seeking an Internet
connection are limited to class C addresses. The current demand for Internet connections will
exhaust the current stock of 32-bit IP addresses. In response, Internet architects have proposed the
next generation of IP addresses, Ipng (IP Next Generation). It will feature 16-byte addressing,
surpassing the capacities of 32-bit IP. Still in its design phase, IPng (also known as IPv6) is not
expected to be widely deployed before the end of this century .

An IP address can serve only a single physical network. Therefore, if your organization has multiple
physical networks, you must make them appear as one to external users. This is done via
“subnetting”, a complex procedure best left to ISPs and others experienced in IP addressing. Since
IP addresses and domain names have no inherent connection, they are mapped together in
databases stored on Domain Name Servers (DNS). If you decide to let an Internet Service Provider
(ISP) administer your DNS server, the ISP can assist you with the domain name and IP address
assignment necessary to configure your company’s site-specific system information. Domain names
and IP addresses are granted by the InterNIC. To check the availability of a specific name or to obtain
more information, call the InterNIC at [phone].

10

MTPSR3-200

Front Panel

The front panel contains three groups of LEDs that provide the status of the LAN connection, link
activity, and general status of the ProxyServer. The EtherNet LAN LEDs display the activity of the
LAN in whether the ProxyServer is connected to the LAN, transmitting or receiving packets, and if a
collision is in progress. The Link LEDs display the status of the three links that can be connected to
the ProxyServer with whether a link is ready to transmit or receive serial data, and if an external
communications device with a V.35 interface is connected to the ProxyServer. The last group of
LEDs indicate whether the self test passed or failed and if the power On/Off switch on the back of the
ProxyServer is turned On.

ETHERNET

RD Receive Data indicator blinks when packets are being received from the local area network.

Chapter 1 - Introduction and Description

Figure 1-2. Front Panel

TD Transmit Data indicator blinks when packets are being transmitted to the local area network.
CL Collision indicator lights when a collision is in progress; that is, when two nodes are

transmitting packets at the same time.

LK Link indicator lights indicating that the ProxyServer is connected to the local area network.

LINK x

RD Receive Data indicator blinks when the link is receiving data.
TD Transmit Data indicator blinks when the link is transmitting data.
CD Carrier Detect indicator lights when the link detects a carrier signal.
TR Terminal Ready indicator blinks when the link is ready to transfer data.
FAIL Fail indicator lights when a self test fails to complete as expected.
POWER The power indicator lights when the On/Off Switch is in the ON position.

MTPSR3-200

11

ProxyServer User Guide

Back Panel

The cable connections for the ProxyServer are made at the back panel. Three groups of cables are
used on the ProxyServer, the Command Port, Link 1 (2 and 3) RJ11, and the EtherNet. The cable
connections are shown in Figure 1-2 and defined in the following groups.

LINK3 LINK2 LINK1 ETHERNET COMMAND POWER

RJ11 LINK Connectors (3)

Link 1 (2 and 3) Connector

These Link 1 (2 and 3) connectors are used to connect the ProxyServer to a WAN. These connectors
are RJ1 1 connectors.

EtherNet 10Base-T Connector

The EtherNet 10Base-T connector is used to connect the ProxyServer to a LAN using unshielded
twisted cable. This connector is an RJ45 jack.

EtherNet 10Base-2 Connector

The EtherNet 10Base-2 connector is used to connect the ProxyServer to a LAN using thin Coax
cable.

10BASET

Ethernet Connectors:
10-BASE T (UTP RJ45)
and 10 BASE 2 (BNC Coax)

10BASE2

Figure 1-3. Back Panel

OFF

Power Connector:
6-pin Cirucular DIN

RJ45 Command
Port Connector

ON

Command Connector

The Command connector is used to configure the ProxyServer using a PC with a serial port and
running Windows® software. The Command connector is an RJ45 jack and a short adapter cable is
provided to convert to a standard serial port DB25 female connector.

Power Connector

The Power connector is used to connect the external power supply to the ProxyServer. The Power
connector is a 6-pin circular DIN connector. A separate power cord is connected to the power supply
and the live AC grounded outlet.

Applications

Applications to be supported later.

12

MTPSR3-200

Specifications

• Protocols - Point-T o-Point Protocol (PPP), Multilink Point-To-Point Protocol (MLPPP), and
Serial Line Internet Protocol (SLIP)

• EtherNet Lan Interface - 10Base-T (twisted pair) or 10Base-2 (ThinNet) BNC connector

• WAN Interface - 3 asynchronous Links (RJ11) jacks

• Command Port - 19.2K bps Asynchronous

• One 1meg by 36 byte at 70 nanosecond SIMM is 4mb DRAM

Caution: SIMM speed and size cannot be mixed

EtherNet Port

• One Ethernet Interface - 10Base-T (twisted pair) RJ45 connector or 10Base-2 ThinNet BNC
connector

Command Port

• Single 19.2K bps asynchronous Command Port using a short RJ45 to DB25 cable with a
DB25 female connector

Chapter 1 - Introduction and Description

WAN Links

• Three internal K56flexTM modems* with MultiLink Point-To-Point Protocol for a bandwidth up
to 168K bps.

Electrical/Physical

• Voltage - 115 VAC (Standard), 240 Volts AC (Optional)

• Frequency - 47 to 63 Hz

• Power Consumption - 10 Watts

• Dimensions - 1.625" high x 6" wide x 9" deep

5.63cm high x 22.34cm wide x 33.51cm deep

• Weight - 2 pounds (.92 kg)

Requirement

• PC with Windows 3.1x, and one serial comm port to connect to the Command Port of the
ProxyServer

* Though this modem is capable of 56K bps download performance, line impairments, public

telephone infrastructure and other external technological factors currently prevent maximum 56K
bps connections.

MTPSR3-200

13

ProxyServer User Guide

14

MTPSR3-200

Chapter 2 - Installation

ProxyServer User Guide

Introduction

This chapter is organized in the way you will unpack and cable your ProxyServer. The unpacking
section describes the contents of the shipping box and shows how the ProxyServer is packaged. The
installation procedure describes each cable connection and shows where that cable is connected to
the ProxyServer.

Unpacking

The shipping box contains the ProxyServer, external power supply, a plastic bag containing cables,
your Quick Start Guide, and two diskettes (i.e., the ProxyServer 200-Series User Guide, and the
ProxyServer Software). Inspect the contents for signs of any shipping damage. If damage is
observed, do not power up the unit, contact Multi-Tech’s Technical Support for advice (refer to
Chapter 7). If no damage is observed, place the ProxyServer in its final location and perform the
Installation Procedure in Table 2-1.

Save the shipping box in case reshipment is necessary .

Quick Start Guide

Figure 2-1. Unpacking

MultiExpress

16

MTPSR3-200

Installation

The installation procedure in Table 2-1 provides the cable connections for up to three WANs, two
types of connections for your ethernet, a short adapter cable to connect to your PC for software
loading, and finally your power connection. If additional RAM needs to be added, perform the
procedures in Table 2-2. Figure 2-2 shows the ProxyServer’s external connections.

Step Procedure

1 If additional RAM needs to be added, perform the procedures in Table 2-2.

Chapter 2 - Installation

T able 2-1. Installation Procedure

WAN Connections

LINK3 LINK2 LINK1 ETHERNET COMMAND POWER

10BASET

10BASE2

PC Connection

Ethernet Connection

Figure 2-2. Back Panel Connections

ON

OFF

Power Connection

2 Connect the external power supply to the ProxyServer and a live AC outlet. The POWER

connector on the back panel of the ProxyServer is a 6-pin circular DIN connector.

3 Connect a PC running Windows® to the COMMAND connector on the back panel of the

ProxyServer. Use the short RJ45 to DB25 cable provided with your ProxyServer to connect

directly to your PC, or to the serial cable from your PC.
4 Configure the ProxyServer for your application using the procedures in Chapter 3.
5 Connect a network cable to either the ETHERNET 10BASE-T (RJ45) or a coax cable to the

10BASE-2 (BNC) connector on the back panel of the ProxyServer. Connect the other end of the

cable to the network.
6 Connect an RJ1 1 phone cable for the first link connection to the LINK 1 connector on the back

panel of the ProxyServer. Connect the other end of the cable to the line jack. Connect the second

RJ1 1 phone cable to the LINK 2 connector on the ProxyServer and the other end to the second

line jack. Connect the third RJ1 1 phone cable to the LINK 3 connector and to the third line jack.

MTPSR3-200

17

ProxyServer User Guide

Adding Additional RAM

A second SIMM connector is provided for adding addition RAM to the ProxyServer. The procedure for
adding additional RAM is provided in Table 2-2.

T able 2-2. Adding Additional RAM Procedure

Step Procedure

1 Ensure that the external power supply is disconnected from the ProxyServer.
2 Turn the ProxyServer upside down and remove the two cabinet mounting screws midway back,

along the edges of the base.

Cabinet
Mounting
Screws

Figure 2-3. Cabinet Mounting Screws

3 Turn the ProxyServer right side up and tilt the back down slightly and the base will slide out of the

cabinet.

4 Place the unit with the LEDs facing you.
5 Slant the SIMM at a 45 0 angle to the back of the base and align the centering notch of the SIMM

with the center tab on the SIMM connector.

6 Gently press down on the ends of the SIMM until the two latches latch over the SIMM and the

two vertical pins enter the holes in the SIMM.

Figure 2-4. Installing a SIMM

7 Slide the base back into the cabinet with the LEDs going toward the front and the back side

grounding tabs pressing against the side of the cabinet.

8 Turn the ProxyServer upside down and replace the two cabinet mounting screws that were

removed in step 2.

9 Turn the ProxyServer right side up and return to Table 2-1 to connect the cables.

18

MTPSR3-200

Chapter 3 - Software Loading

and Configuration

ProxyServer User Guide

Introduction

This chapter covers procedures for loading the software and configuring your ProxyServer.

Loading your Software

1 Turn on your PC connected to the Command Port of your ProxyServer and run Windows®.
2 Create a backup copy of your ProxyServer software diskette before you install the software.

Store the master diskette in a safe place and install the ProxyServer software using the backup
copy .

3 Insert the Proxy Server diskette into the disk drive on the pc connected to the Command Port.
4 Win3.1 users - you can access Run by clicking on the File menu in Program Manager and then

clicking on Run.
Win95 users - click on the Start box and then click on Run.

5. In the Run dialog box, type a:\install or b:\install (depending on the location of your floppy disk
drive) in the Command Line field and then click on OK.

6. Follow the on-screen instructions to install the Proxy Server software.

IP Port Configuration

This dialog allows for the configuration of IP parameters that are generally applicable to IP Proxying
on all ports.

7. The default LAN IP address has to be changed to your unique LAN address.

8. If your ISP dynamically assigns the W AN port IP addresses, do nothing and proceed to the next
step.

If a static WAN IP address needs to be assigned, highlight WAN 1, then click on the ISP assigns
Dynamic Address check box to disable the feature, then click on the IP Address field and enter
your IP WAN 1 address. Also, enter the Net Mask for WAN 1.

Highlight WAN 2 and repeat the above process.
Highlight WAN 3 and repeat the above process.

20

MTPSR3-200

Chapter 3 - Software Loading and Configuration

9. For the Client Side Internet Parameters, click on the Gateway Address field and enter your

gateway IP address.

10. Click on OK button and the WAN Port Setup dialog is displayed.

Default WAN Links Configuration

11. Determine if MultiLink PPP (MLPPP) is going to be enabled, i.e., all three WAN links bonded

together. If MLPPP is going to be used, then click on MultiLink PPP and proceed to step 12.
If MLPPP is not going to be used, proceed to step 18.

12. Click on Dial Number for WAN 1 and enter the telephone number supplied by your ISP for WAN

1. The telephone number can be a standard local number and it can include a long distance
prefix.

13. Click on User Name for WAN 1 and enter your user name that you negotated with your ISP for

WAN 1. The User Name can be up to 40 alphanumeric characters. The User Name is not case
sensitive.

14. Click on Password for WAN 1 and enter your password that you negotated with your ISP for

WAN 1. The password can be up to 15 alphanumeric character and also is not case sensitive.

15. Repeat the above three steps for WAN 2.

16. Repeat the above three steps for WAN 3.

17. Click on OK button to continue installing the software

18. If the WAN ports are not bonded together (no MLPPP), but are used as individual WAN ports

being connected to the same ISP, click on Dial Number for WAN 1 and enter the telephone
number supplied by your ISP for WAN 1. The telephone number can be a standard local number
and it can include a long distance prefix.

19. Click on User Name for WAN 1 and enter your user name that you negotated with your ISP for

WAN 1. The User Name can be up to 40 alphanumeric characters. The User Name is not case
sensitive.

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ProxyServer User Guide

20. Click on Password for WAN 1 and enter your password that you negotated with your ISP for
WAN 1. The password can be up to 15 alphanumeric character and also is not case sensitive.

21. Repeat the above three steps for WAN 2.

22. Repeat the above three steps for WAN 3.

23. Turn on power to the Proxy Server and the Checking Router dialog box is displayed.

The Setup utility is “Ready to Download default Setup Choose OK to proceed.” Click on OK to
proceed.

24. Writing Setup dialog box is displayed as the setup configuration is written to the Proxy Server.

25. After the setup is written to the Proxy Server, the unit is rebooted.

26. Win3.1 users - you are returned to your Program Manager where the Proxy Server Program
Group and Program Item (Windows icons) have been created.

Win95 users - you are returned to your ProxyServer folder which will be visible on your desktop.

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Chapter 4 - ProxyServer Software

ProxyServer User Guide

Introduction

This chapter describes the ProxyServer 200-Series Proxy Server software package which is
designed for the Microsoft ® Windows ® environment. The Proxy Server Program Group has five
icons that allow you to configure your Proxy Server, download a default setup or firmware update,or
configure a local port from the Program Manager by double clicking on one of the icons.

Two levels of describing the Proxy Server software are provided; the Help screens contained in the
application provide the first level which is to define the options in a dialog box, the second level define
a task and how the dialog boxes need to be setup to perform that task. For example, in the IP Setup
dialog box, the LAN IP Address must be a static address that is assigned by the LAN Administrator.
This address must be unique to your LAN. This information is provided in the on-line Help. Now , the
task of assigning an LAN IP Address is described in this User Guide and covers the dif ference
between a static IP Address and a dynamic IP Address assigned by your local ISP as the port is
activated. The task approach in this User Guide is going to assume that you have access to the
Helps and therefore will not go into defining options or buttons within a dialog box, but more into the
task that need to be performed.

Before You Begin

Before you begin, let’s cover a few procedural matters so that they are out of the way.
To view or change your ProxyServer configuration, double click on the Proxy Server Configuration

icon.
You may also start Proxy Server Configuration from the File Manager by selecting the Proxy directory

and double clicking on the roucon.exe program in the file list. Local port setup can also be started
from File Manager by selecting psetup.exe from the file list.

You may also run Proxy Server Configuration from either the Program Manager or the File Manager
by clicking on the Run command in the File Menu, then typing: C:\ proxy\ roucon.exe in the
Command Line field. Local port setup can also be run from the Command Line by typing: C:\ proxy\
psetup.exe.

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MTPSR3-200

Setup Menu

The Proxy Server Setup menu organizes your configuration process into two categories: Stacks and
Drivers, and Other Setup. The Stacks and Drivers define the Proxy Server IP Protocol stack and the
device drivers define how the WAN is used, i.e., Point-to-Point Protocol (PPP), MultiLink PPP,
(MLPPP), or Serial Line IP Protocol (SLIP) .

The other Setup group defines the proxied applications, the Dynamic Host Configuration Protocol
(DHCP) for assigning IP parameters to the workstations on the LAN, applications such as TFTP for
transferring files between two nodes, telnet for terminal emulation at a remote workstation, and
filtering of data packets for getting through the link.

Chapter 4 - ProxyServer Software

Certain options are enabled depending on the state of the target. If no ProxyServer (target) is found,
click on the Configuration Port Setup icon in the ProxyServer program group, specify the right local
port parameters and retry running this application. You can also connect to the target through a dialup
modem.

ProxyServer setup also has a console terminal for displaying various debugging messages output
from the target. You can control the display of these messages using this application. Normally you
should turn off the display of all messages for better performance of the router .

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ProxyServer User Guide

Setting up your IP Addresses

Considerations for setting up your IP addresses; the LAN address is a static address that is unique to
your LAN, the WAN addresses can be static address which you have to enter or dynamic address
that are assigned by your ISP.

When the IP setup dialog box is displayed and the LAN is highlighted, the ISP Assigns Dynamic
Address option is greyed out (not active). The IP Address and Net Mask fields are active. This
requires you to enter you unique LAN IP address and net mask for your LAN.

Now consider the WAN ports, are they going to be assigned dynamically by your ISP or are you
going to have to enter WAN IP addresses and net masks for each WAN port. The majority of the time
the WAN addresses are going to dynamically asssigned by your ISP. If the addresses are being
assigned dynamically by your ISP when the port is activated, you do not have to do anything for the
WAN ports in this dialog box.

If the WAN port IP addresses are static addresses in which you own the IP addresses, you have to
click on ISP Assigns Dynamic address option which disables the option and assign IP addresses for
your WAN ports. If you are using Point-to-Point Protocol (PPP) or Serial Line IP Protocol ((SLIP), the
WAN port IP address have to be unique for each port. If you are using MultiLink PPP (MLPPP), only
one IP address is required for all three WAN ports.

The Client side Internet Parameters Gateway Address field is used if a second router is connecting
two LANs together. Then the Gateway Address of the router on your LAN would be entered in this
field.

An IP address is a combination of a network number and a host number or ID. IP address masks are
used to specify the network or subnet portion of the IP address. IP addresses and masks are 32-bit
values. These are usually provided in what is known as the dotted decimal notation. In this notation,
each 8-bit portion of the address is given a decimal quantity separated by a dot. For example,

192.2.10.1. The Proxy Server expects all IP addresses to be provided in dotted decimal notation.

Among IP addresses, address 0.0.0.0 and 127.?.?.? cannot be specified as they are special case
addresses not used on the internetwork for addressing. For Class A, B, and C addresses, you will
usually specify address masks of 255.0.0.0, 255.255.0.0 and 255.255.255.0 respectively unless other
subnets have been set up.

The net mask specifies the network or subnet portion of an IP address. The net mask is a 32-bit
value presented in a dotted decimal notation.

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MTPSR3-200

Selecting your WAN Protocol

Before selecting your WAN protocol you must know what protocol your ISP uses. Most ISPs use
Point-to-Point Protocol (PPP), and if the ISP is capable of bonding the three WANs together for
increased bandwidth, they may be using MultiLink PPP (MLPPP) protocol. The other protocol an ISP
might be using is Serial Line IP (SLIP) -- an older protocol that is not as robust as PPP.

If PPP is the protocol the ISP is using, the User Names and Passwords may or may not be the same
depending on whether your ISP allows multiple sessions on the same User Name and Password.

If MLPPP is the protocol, then the User Names and Passwords must be identical; otherwise, analog
channel bonding will not occur.

If SLIP is the protocol of choice, manual authentication has to be performed using a script.

Chapter 4 - ProxyServer Software

PPP is the default protocol. If PPP is the protocol being used, click on the User Name field and enter
your user name. Then click on Password field and enter your password.

If MLPPP is the protocol being used, from the PPP Port Setup dialog box, click on the Advanced
button and the PPP General Setup dialog box is displayed. Click on the MultiLink PPP (MLPPP)
option to enable MLPPP for all three WAN links. Click on the OK button to return to the PPP Port
Setup dialog box. Then enter a unique User Name and Password for all three WAN links. Click on the
OK button to return to the Proxy Setup dialog box.

If SLIP is being used, click on the PPP Enable option to disable PPP. The SLIP group then becomes
active. Click on the SLIP Enable option. Determine if the TCP header is going to be compressed
using VJC compression. If VJC compression is used, click on the CSLIP (Van Jacobson
Compression) option. SLIP requires that an authentication script be written when you are in the WAN
Port Setup dialog box. When you have SLIP configured for your network, click on the OK button to
return to the Proxy Setup dialog box.

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ProxyServer User Guide

Activating your WAN Ports

Activating your WAN ports depends on how your ISP is setup; if your ISP is capable of rolling over a
telephone number, then you have to enter the same telephone number in the Connection Method Dial
Number field for each WAN link. The majority of the time the ISP is going to be able to roll over the
number. You will have to find out from your ISP what there capability is before you enter the
telephone number in this dialog box.

If the ISP is not capable of rolling over the telephone number , then you will have to enter three
telephone numbers, one for each WAN link.

The other consideration in activating your WAN ports is if you activated SLIP as a protocol in the PPP
Port setup dialog box. If SLIP is the protocol, then you may have to create a script for SLIP.

Scripting

The ProxyServer supports a scripting facility on WAN ports that are configured as asynchronous.
This feature can be very useful when some special handling has to be done on the WAN port (e.g.,
extra authentication, special communications equipment, etc.). Click on the Script button to create or
edit a script for the WAN port. You can click on the Script Enable option to activate a script for the
selected WAN port. You can also Restart a Script On Communication Failure by clicking on this
option. Refer to Appendix B for details on the Router Scripting Language.

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Changing Proxy Applications

The most common proxy applications are loaded on your ProxyServer and are shown in the Proxy
Applications Configuration dialog box. To add additional applications, refer to the assigned numbers
described in RFC 1700 at ftp://ds.internic.net/rfc/rfc1700.txt on your WEB.

Chapter 4 - ProxyServer Software

Adding Client IP Addresses for the DHCP Server

The DHCP Server allows you to customize each client PC configuration from one central point. You
can establish a range of client addresses in the Manage Addresses dialog box. You can then exclude
specific addresses from that range in the Exclude From/Exclude Up To dialog box. You can also Add,
Remove, View and Bind addresses in this dialog box.

In the Options T ypes and Values dialog, you can customize the configuration of the client platform.
The Option T ype and Name are displayed in the left dialog and the values for that option are
displayed in the right dialog. You can Add and Remove values using the respective buttons.

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ProxyServer User Guide

Enabling Remote Servers

This dialog box lets you set up support for Telenet, TFTP (Trivial File Transfer Protocol), WEB server,
and dumb terminal managment in the ProxyServer.

Telnet is an applications level protocol commonly found in IP based networks that allow terminal
emulation at a remote workstation. To do this, there is usually a server at a central point that allows
multiple clients to connect and request to use the service. The service could be anything. Usually it is
terminal emulation. The MultiRotuer has a Telnet server that allows multiple clients to view statistics
information from the box. Telnet is usually implemented over TCP.

TFTP is a file transfer protocol that uses UDP and provides a simple method for transferring files
between two nodes (one the server and the other the client).

WEB Server

The WEB Server interface allows you to configure the Proxy Server remotely via your WEB browser
on your local network. By entering the IP address of the Proxy Server in the Location (Address) field
of your browser, your are brought to the Multi-Tech Proxy Server Configuration site.

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MTPSR3-200

Chapter 4 - ProxyServer Software

By scrolling down the browser scroll bar, you are presented with a link to login to the Proxy Server
configuration menu (“Click Here to Login”), as well as links to Multi-Tech’s WWW site, ftp site, and
Tech Support site.

Click on the word “Login” and you are brought to the Proxy Server Configuration menu. The default
login ID is “supervisor”, with no password.

The Proxy Server Configuration Menu provides the following configuration categories: Protocol
Stacks, Device Drivers, Other Setup, and statistics for the WAN ports.

Each category contains links which allow configuration of various features. Click on the item you wish
to configure and you are brought to a configuration screen for that feature.

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ProxyServer User Guide

A detailed description of each feature is provided in this Chapter.

Running Diagnostics

ProxyServer Setup program lets you perform various hardware tests on the LAN and WAN links. The
Diagnostic dialog box is displayed by clicking on the Diagnostic button in the Router Setup dialog
box. Diagnostic tests are performed if the Communication type of the Local Port configuration is set
to COM Port. If the Local Port configuration is set for IP, no diagnostic test are performed by the
ProxyServer.

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Chapter 5 - Remote Configuration

ProxyServer User Guide

Introduction

This chapter provides procedures for changing the configuration of a remote unit. Remote
configuration allows a PC at one site (local site) to dial a remote ProxyServer and change the
configuration of that remote unit. Remote configuration can be accomplished either directly through
the LAN or remotely using modems. To remotely configure a ProxyServer, a local PC needs to be
connected to a dial-up line and the ProxyServer software configured to call the remote ProxyServer.
The remote ProxyServer needs to have a modem connected to a dial-up line and the Command Port.
Once the connection to the remote unit is made, you can change the configuration as you see fit.
Once the configuration is changed, you can download the new configuration to the remote
ProxyServer. Refer to the Modem-Based Remote Configuration Procedure in this chapter to remotely
configure a MultiRouter.

To configure the remote ProxyServer through the LAN, change the communication type to the IP
based Trivial File Transfer Protocol (known as TFTP) and change the configuration as you see fit.
Refer to the LAN-Based Remote Configuration Procedure in this chapter to configure a remote
ProxyServer.

Modem-Based Remote Configuration Procedure

1 At the remote site, remove the serial cable from the PC to the Command Port connector on the

back panel of the ProxyServer.

2 At the remote site, connect a special cable (Remote Configuration Cable) to the Command Port

connector on the back panel of the ProxyServer and the RS232 connector on the modem. The
special cable is a serial cable with male connectors on both ends. Refer to Appendix A for for
cable details.

Connect the modem to your local telephone line.
Provide your telephone number to the person verifying your configuration.

3 At the main site, connect your local PC to a modem that is connected to a dial-up line.
4 Install the ProxyServer software on the local PC and at the Windows Program Manager screen,

double click on the Configuration Port Setup Icon.

5 The ProxyServer Setup dialog box is displayed.

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Chapter 5 - Remote Configuration

Verify that the Communication Type field is set for Com port and the Select Port field is set for
the Com port of your local PC.

In the Dial String field, enter the AT command for dialing (ATDT) plus the phone number of the
remote ProxyServer.

If your Modem Initialization String, Initialization Response, or Connect Response values are
different from the defaults in the dialog box, refer to your modem user documentation and change
the default values to match your modem.

Click on OK when you are satisfied with your selections.

6 The windows Program Manager menu is displayed.

Double click on the Proxy Server Configuration icon.
7 The Dialing Router Dialog Box is displayed while software is dialing the remote ProxyServer.
8 The Reading Setup Dialog Box is displayed.

9 The ProxyServer Setup dialog box is then displayed. This is the dialog box of the remote

ProxyServer. Refer to the Menus Chapter (Chapter 4) for the definition of each dialog box and

field within a dialog box.

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ProxyServer User Guide

10 After you have changed the configuration of the remote ProxyServer, click on the Download

Setup button to update the configuration. The remote ProxyServer will be brought down, the new

configuration written to the unit, and the unit will reboot.

1 1 Click on the Exit button when the downloading is complete.
12 The Hangup connection with Router? dialog box is displayed.

Click on the Yes button to disconnect the phone connection to the remote site.

13 If the same telephone number is not going to be used again in the immediate future, you may

want to remove it from the Port Setup dialog box.

14 At the remote site, reconnect the ProxyServer to the serial port of the PC and from the Program

Manager screen click on the Proxy Server Configuration icon to verify that the ProxyServer is
running.

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LAN-Based Remote Configuration

Windows Sockets Compliant TCP/IP Stack

The configuration program requires a Windows Sockets compliant TCP/IP stack. Microsoft provides a
TCP/IP stack free for Windows for Workgroups 3.11. TCP/IP protocol software must be installed and
functional before the configuration program can be used.

1 You must assign an internet (IP) address for the PC and for each node that will be managed by

the configuration program. Refer to the protocol software documentation for instructions on how

to set the IP addresses.

Once you have completed this step, you should be able to use the protocol Ping command for

the PC host name. You should also test the network interface configuration by Pinging another

TCP/IP device that is connected to the network.
2 Install the ProxyServer software on the local PC and at the Windows Program Manager screen,

double click on the Configuration Port Setup Icon.

Chapter 5 - Remote Configuration

3 The ProxyServer Setup dialog box is displayed.

Verify that the Communication Type field is set to IP.

In the Router IP Address field, enter the IP Address of the remote ProxyServer.
4 Click on OK when you are satisfied with your selections.

The Windows Program Manager menu is displayed.

MTPSR3-200

37

ProxyServer User Guide

5 Double click on the Proxy Server Configuration icon.

The Reading Setup dialog box is displayed.

6 The ProxyServer Setup dialog box is then displayed. This is the dialog box of the remote

ProxyServer. You can select any of the Protocol Stacks, Device drivers, or other buttons and
change the configuration of the remote ProxyServer. Refer to the Menus Chapter (Chapter 4) for
the definition of each dialog box and field within a dialog box.

7 After you have changed the configuration of the remote ProxyServer, click on the Download

Setup button to update the configuration. The remote ProxyServer will be brought down, the new
configuration written to the unit, and the unit will reboot.

8 Click on the Exit button when the downloading is complete.
9 Click on the Proxy Server Configuration icon in the Program Manager screen to verify that the

ProxyServer is running.

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Chapter 6 - Router Management

ProxyServer User Guide

Introduction

A typical Telnet client application is described in this chapter. The ProxyServer 200-Series Proxy
Server has a built-in Telnet Server for access to the ProxyServer through Telnet clients. A typical
Telnet client is allowed to configure the Proxy Server and WAN devices. A typical TCP/IP program
group is shown below with a Tcpman icon and a Telnet icon.

For a detailed description of the Proxy Server software and individual parameters, refer to Chapter 4
in this User Guide.

The TCP/IP stack has to be loaded before the Telnet client can run. The Telnet client is a Windows
application. The Telnet Server option has to be selected from the Applications Setup dialog box using
the Proxy Server Configuration icon. Double click on the Telnet icon and a blank Telnet screen is
displayed. Click on Connection and a drop down menu is displayed. Click on Connect and the
Connect to remote host dialog box is displayed.

When the Connect to remote host dialog box is displayed, a Host address has to be entered. In this
example, the IP Host address is 192.168.0.1.

When you enter a host address and click on the OK button, the Proxy Server Management menu is
displayed.

Proxy Server Management Menu

The Proxy Server management menu provides two options; proxy server configuration and WAN
device configuration. The proxy server configuration options allow you to select the protocol stack,
high or low level device drivers, applications, proxy server, or system information. The WAN device
configuration allows you to gain access to the WAN ports.

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Proxy Server Configuration

The Proxy Server Configuration option allows you to view and change parameters on the protocol
stacks, high and low level device drivers, enable or disable the supported servers, change proxy
applications, or view system information. If the password option is enabled, you will be prompted for a
password.

To select an option, enter the number of the option and hit the Enter key . For example, to select the
Protocol Stacks option, enter 1 and hit the Enter key . For details on a parameter, refer to the on-line
helps and Chapter 5 of this manual.

Chapter 6 - Router Management

Applications

The Applications option from the proxy server configuration menu allows you to enable or disable
various servers. Choosing the Applications option (Option 4) in the menu displays the various
servers.

The Applications menu displays three server options for your choice. To enable or disable a server,
choose the server option number and hit the Enter key . Then choose either option 1 to enable the
server or option 2 to disable the server.

The following is a description of each server and its use.
TFTP Server - The TFTP server is used for configuration and firmware updates across the IP

internetwork. TFTP is a file transfer protocol that uses UDP and provides a simple method for
transfering files between two nodes (the server and client).

T elnet Server - The Telnet server allows an authorized Telnet client to remotely access the Telnet
server to dial out, view router configuration and statistics, modify the router configuration, or remotely
modify the user database.

Dumb TTY - The Dumb TTY allows a remote user to connect to the ProxyServer’s command port for
configuration and management of the ProxyServer.

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ProxyServer User Guide

42

MTPSR3-200

Chapter 7 - Service, Warranty

and Tech Support

ProxyServer User Guide

Introduction

This chapter starts out with statements about your ProxyServer 2-year warranty . The next section,
Tech Support, should be read carefully if you have questions or problems with your ProxyServer. It
includes the technical support telephone numbers, space for recording your product information, and
an explanation of how to send in your ProxyServer should you require service. The final three
sections explain how to use our bulletin board service (BBS), and get support through CompuServe
and the Internet.

Limited Warranty

Multi-Tech Systems, Inc. (“MTS”) warrants that its products will be free from defects in material or
workmanship for a period of two years from the date of purchase, or if proof of purchase is not
provided, two years from date of shipment. MTS MAKES NO OTHER WARRANTY, EXPRESSED
OR IMPLIED, AND ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. This warranty does not apply to any
products which have been damaged by lightning storms, water, or power surges or which have been
neglected, altered, abused, used for a purpose other than the one for which they were manufactured,
repaired by the customer or any party without MTS’s written authorization, or used in any manner
inconsistent with MTS’s instructions.

MTS’s entire obligation under this warranty shall be limited (at MTS’s option) to repair or replacement
of any products which prove to be defective within the warranty period, or, at MTS’ s option, issuance
of a refund of the purchase price. Defective products must be returned by Customer to MTS’s factory
transportation prepaid.

MTS WILL NOT BE LIABLE FOR CONSEQUENTIAL DAMAGES AND UNDER NO
CIRCUMSTANCES WILL ITS LIABILITY EXCEED THE PURCHASE PRICE FOR DEFECTIVE
PRODUCTS.

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Tech Support

Multi-Tech has an excellent staff of technical support personnel available to help you get the most out
of your Multi-Tech product. If you have any questions about the operation of this unit, call 1-800-972-

2439. Please fill out the ProxyServer information (below), and have it available when you call. If your
ProxyServer requires service, the tech support specialist will guide you on how to send in your
ProxyServer (refer to the next section).

Recording ProxyServer Information

Please fill in the following information on your Multi-Tech ProxyServer. This will help tech support in
answering your questions. (The same information is requested on the Warranty Registration Card.)

Model No.: _________________________
Serial No.: _________________________
Software Version: ____________________

The model and serial numbers are on the bottom of your ProxyServer.
Please note the type of external link device that is connected to your ProxyServer before calling tech

support. Also, note the status of your ProxyServer including LED indicators, screen messages,
diagnostic test results, DIP-Switch settings, problems with a specific application, etc. Use the space
below to note the ProxyServer status:

Chapter 7 - Service, Warranty and Tech Support

________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
______________________________________________________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________________
______________________________________________________________________________________________________

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ProxyServer User Guide

Service

If your tech support specialist decides that service is required, your ProxyServer can be sent (freight
prepaid) to our factory . Return shipping charges will be paid by Multi-Tech Systems.

Include the following with your ProxyServer:

• a description of the problem.

• return billing and return shipping addresses.

• contact name and phone number.

• check or purchase order number for payment if the ProxyServer is out of warranty. (Check

with your technical support specialist for the standard repair charge for your ProxyServer).

• if possible, note the name of the technical support specialist with whom you spoke.

If you need to inquire about the status of the returned product, be prepared to provide the serial
number of the product sent.

Send your ProxyServer to this address:

You should also check with the supplier of your ProxyServer on the availability of local service and/or
loaner units in your area.

MULTI-TECH SYSTEMS, INC.

2205 WOODALE DRIVE

MOUNDS VIEW, MINNESOTA 55112

ATTN: SERVICE OR REPAIRS

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About the Multi-Tech BBS

Multi-Tech Systems maintains a Bulletin Board Service (BBS) for its customers. The information
available via the BBS includes: new product information, product upgrade data, problem solving tips,
and a message service for you to leave questions for which you would like additional information. The
phone number for the Multi-Tech BBS is [phone] or [phone] (U.S.A. and Canada).

The BBS can be accessed by any asynchronous modem operating at speeds of 33,600 -1200 bps
with a setting of word length of 8 bits, 1 stop bit, and no parity .

Logging on to the Multi-Tech BBS

To log on to the Multi-Tech BBS, perform the following steps.

1. Set your communications program to 8-N-1.

2. Dial our BBS at [phone] (USA and Canada) or [phone] (international and local).

3. At the prompts, type your first name, last name, and password; then press RETURN. If you are a

first time caller, the BBS will ask if your name is spelled correctly. If you answer yes, a

questionnaire will appear. You must complete the questionnaire to use the BBS on your first call.

4. Press RETURN until the Main Menu appears. From the Main Menu you have access to three

main areas: the Files Menu, the Message Menu, and Bulletins. For help on menu commands,

type ?.

Chapter 7 - Service, Warranty and Tech Support

Downloading a File

If you know the file name

1. From the Main Menu, type F to access the Files Menu, then type D.

2. Enter the name of the file you wish to download from the BBS.

3. If a password is required, enter the password.

4. Answer Y or N to the automatic logoff question.

5. Select a file transfer protocol by typing the indicated letter, such as Z for Zmodem (the

recommended protocol).

6. If you select Zmodem, the transfer will begin automatically . If you select another protocol, you

may have to initiate the transfer yourself. (In most datacomm programs, the P AGE DOWN key

initiates the download.)

If you don’t know the file name

1. From the Main Menu, type F to access the Files Menu. For a list of file areas, type L twice. (If you

do not type the second L, you will list all of the files on the BBS.)

2. Mark the file areas you would like to examine by typing each file area’s list number and a

RETURN.

3. Enter L to list all the files in the selected file areas. Enter C to go forward in the file list and P to

go back.

4. Mark one or more files for download by entering M, the list numbers of the files, and a RETURN.

5. Enter D. You will see a list of the files you have marked. Enter E if you would like to edit the list;

otherwise enter D again to start the download process.

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ProxyServer User Guide

6. Select a file transfer protocol by typing the indicated letter, such as Z for Zmodem (the
recommended protocol).

7. If you select Zmodem, the file will transfer automatically . If you select another protocol, you may
have to initiate the transfer yourself. (In MEWTERM and many other communications programs,
the P AGE DOWN key initiates the download.)

8. When the download is complete, enter S to return to the File Menu.

Reading a Message

When you log on, the BBS will tell you if you have a personal message (mail). At the prompt Would
you like to read it now?, type R to read the message. This is the only point at which you can read
your mail, since you cannot read any messages from the Message Menu.

Leaving a Message

The Multi-Tech BBS has no public discussion areas. To leave a personal message, select the
Message Menu by typing M at the Main Menu. Type E, then press RETURN to select the Sysop
conference. Enter the name of the recipient (or “Sysop”), the subject, and the message text. Press
ESCAPE to finish, then type S to save the message and exit. To abort the message at any point,
leave any of the fields blank and press RETURN.

Bulletins

When you log on, the BBS will ask if you would like to view the bulletin menu. The bulletins are
menu-driven; to read a bulletin, enter its number. You can also access the bulletins by typing B at the
Main Menu.

About CompuServe

In addition to the BBS, Multi-Tech provides support through CompuServe’s Modem V endor Forum
(GO MODEMVEN). Refer to your Compuserve documentation for special operating procedures.

About the Internet

Multi-Tech is a commercial user on the Internet, and we retrieve messages from our customers on a
periodic basis. If you prefer to receive technical support via the Internet, you can contact Tech
Support via e-mail by clicking on the following link:

T echnical Support E-mail

Multi-Tech’s presence includes a Web site at:

http://www.multitech.com

and an ftp site at:

ftp://ftp.multitech.com

The ftp server mirrors the Multi-Tech BBS.

48

MTPSR3-200

Chapter 7 - Service, Warranty and Tech Support

About the Multi-Tech Fax-Back Service

Multi-Tech’s fax-back system provides 24-hour access to sales, marketing, and technical literature.
Dial 612-717-5888, follow the voice prompts, and request document number 10 for a catalog of
available documents. For convenence, have your fax number handy: _________________________.
From the catalog of available documents, you can order newsletters, white papers, press releases,
etc. from the sales and marketing index (pages 1-4), or order basic modem operation and
troubleshooting guides from the technical support and engineering index. Just enter the applicable
FB Doc. # from the left column of the catalog.

MTPSR3-200

49

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50

MTPSR3-200

Appendices

ProxyServer User Guide

Appendix A - Cabling Diagrams

Command Port Cable

13 12 11 10 9 8 7 6 5 4 3 2 1

25 24 23 22 21 20 19 18 17 16 15 14

LAN Cables

Pin Circuit Signal Name Pin Description

1 TD+ Data Transmit Positive 1 Center

To COMMAND PORT
Connector

10BASE T

PIN NO.

1 2 3 4 5 6 7 8

PIN NO.

1
2
3
4
5
6
7
8
20
22
25

1
2
3
4
5
6
7
8
20
22
25

TRANSMIT DATA (BA)
RECEIVE DATA (BB)

SIGNAL GROUND (AB)

To
DTE
Device

(Terminal
Device
i.e. ASCII
Terminal)

10BASE 2

Center

Shield

2 TD- Data Transmit Negative 2 Shield
3 RD+ Data Receive Positive
6 RD- Data Receive Negative

Remote Configuration Cable

PIN NO.

1
2
3

To
COMMAND PORT
Connector

4
5
6
7
8
20
22
25

Male

PIN NO.

1
2
3
4
5
6
7
8
20
22
25

Male

FRAME GROUND
TRANSMIT DATA (TX)
RECEIVE DATA (RX)
REQUEST TO SEND (RTS)
CLEAR TO SEND (CTS)

SIGNAL GROUND

To
DCE
Device

(Communication
Device
i.e. Modem)

52

MTPSR3-200

Appendix B - Script Language

The script file can be used to automate certain operations. The script file is a text file containing a
sequence of commands. The structure of a script file is succinctly expressed by the following
grammar.

Script Language Grammar

<program> =<declarations> <proc_declarations>
<declarations> ={<var_type> <identifier> {, <identifier> } ; }
<var_type> =INTEGER I STRING
<statement_list> ={<statement>}
<statement> =<elementary_statement> I <if_statement> I<for_statement> I

<while_statement> I <switch_statement>
<if_statement> =IF <expression> THEN <statement_list> {ELSE<statement_list> } ENDIF
<for_statement> =FOR <identifier>=<expression> TO IDOWNTO <expression} STEP

<expression> / DO <statement_list> ENDFOR
<while_statement> =WHILE <expression> DO <statement_list> ENDWHILE
<switch_statement> =SWITCH <expression> {CASE <integer_const> <statement_list> I

CASE <string_const> <statement_list> I

DEFAULT <statement_list> }

ENDSWITCH
<elementary_statement> =<identifier> = <expression> ; I <identifier> / (<expression>

{,<expression> } ) /; I GOTO <identifier> ; I <identifier> : I ;
<expression> =<expression> OPERATOR <expression> I {<expression> } I /<expression>I

- <expression> I<identifier> / (<expression> {, <expression> } ) /
OPERATOR = < I <= I > I >= I == I != I && I II I + I - I * I / I !
<proc_declaration> =PROC <identifier>/(<parameter_list>)} { :<vartype> };FORWARD ;
<proc_declaration> =PROC <identifier>/(<parameter_list>)} / : <vartype> / ;

<declarations> <statement_list>ENDPROC
<parameter_list> =<argument_list> { ; <argument_list>}
<argument_list> ={V AR} <var_type> <identifier> {<identifier>}
Execution starts at the PROC main. PROC main cannot have any arguments. All the variables have
to be declared before use. All procedures must be declared before calling. Recursion is allowed in
procedures.

Appendices

To define mutually recursive procedures, use the FORWARD directive to indicate that the procedure
body is defined later in the source file. Procedures defined with the FORWARD directive should have
all the parameters and return value (if any) specified, the actual definition of the procedure body
should not contain the formal parameter list or the return value. An example of forward defined
procedures is given below:

proc a(integer x,y) : integer,forward:
proc b(integer u,v) : integer,forward:
proc a;

integer t;
/*Some more code here. */

t=b(x,y);
/*Some more code here. */
return(t);

endproc
proc b;

return(a(u,v);

endproc

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ProxyServer User Guide

Argument to procedures can be passed by value or address. To pass an argument by address, prefix
the argument name in the formal parameter list by the keyword VAR; otherwise the argument is
passed by value. Only variables can be passed by address. Expressions like A+B, where A and B
are integer variables can be passed by value but cannot be passed by address.

Two basic types of variables are supported:

INTEGER and STRING
In the STRING, since the ASCII null character is internally used to indicate the end of the sequence,

it cannot be part of the string. All other characters, including extended ASCII characters can be part
of the string.

There are two types of conditional constructs:

IF and SWITCH
The IF statement is a two-way branching construct. The condition can be an arbitrary expression.

The condition in the IF statement should evaluate to an integer or real. If the expression in the IF
statement evaluates to non-zero, the control enters the THEN statement, otherwise control enters the
ELSE statement.

The SWITCH statement is a multi-way branching construct. The type of conditional expression
should be either INTEGER or STRING. The value of the conditional expression is matched against
the constraints given in the CASE options, if the value matches a CASE option value, control enters
that CASE option. If the values do not match any of the CASE options, and if a DEFAULT option is
provided, control continues at the DEFAULT option; otherwise control continues at the statement after
the ENDSWITCH. If control enters one of the CASE or DEFAULT statements, all the statements up
to the next ENDCASE statement are executed. Each CASE or DEFAULT statement should be
terminated by a matching ENDCASE keyword. The SWITCH statement should be terminated by a
ENDSWITCH keywork. The DEF AULT statement can be placed anywhere within the scope of the
SWITCH statement. There can be only one DEF AULT statement.

There are two types of iterative constructs:

FOR and WHILE
The FOR construct sets the loop control variable to an initial value. The control variable is checked

for bounds, and if within bounds, the <statement_list> given is executed; otherwise the loop
execution terminates. After each execution of <statement_list>, the control variable is incremented or
decremented by a certain value. This is computed as follows: if the STEP expression is given it is the
value of the expression, else it is 1. The control variable is incremented if TO is specified, and is
decremented if DOWNTO is specified. After updating the control variable the bounds check is done
again. The keyword ENDFOR is mandatory at the end of the loop.

The WHILE loop has an expression and a <statement_list>. The expression is evaluated and if the
expression is non-zero the <statement_list> is executed; otherwise the loop execution terminates.
The keyword ENDWHILE is mandatory at the end of the loop.

Operator Precedence:

Operators are listed in the order of precedence
Unary Operators :-!(unary minus, logical negation)

Binary Operators :*/ + _< > <= >= == ! = && II
All the operators are left associative. Expressions are evaluated completely; so care must be taken

while writing expressions. For example, expressions like (a !=0 && b / a) would create run time error.

54

MTPSR3-200

Appendices

Appendix C - Regulatory Information
FCC Declaration

NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device,

pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against
harmful interference when the equipment is operated in a residential installation. This equipment generates,
uses and can radiate radio frequency energy, and if not installed and used in accordance with the
instructions, may cause harmful interference to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does cause harmful interference to
radio or television reception, which can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of the following measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between the equipment and receiver.

• Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.

• Consult the dealer or an experienced radio/TV technician for help.

Warning: Changes or modifications to this unit not expressly approved by the party responsible for
compliance could void the user’s authority to operate the equipment.

FCC Regulations for Telephone Line Interconnection

1. This equipment complies with Part 68 of the Federal Communications Commission (FCC) rules. On the
outside surface of this equipment is a label that contains, among other information, the FCC registration
number and ringer equivalence number (REN). If requested, this information must be provided to the
telephone company.

2. As indicated below, the suitable jack (Universal Service Order Code connecting arrangement) for this
equipment is shown. If applicable, the facility interface codes (FIC) and service order codes (SOC) are
shown. An FCC-compliant telephone cord and modular plug is provided with this equipment. This equipment
is designed to be connected to the telephone network or premises wiring using a compatible modular jack
which is Part 68 compliant. See installation instructions for details.

3. The ringer equivalence number (REN) is used to determine the number of devices which may be
connected to the telephone line. Excessive REN’s on the telephone line may result in the devices not ringing
in response to an incoming call. In most, but not all areas, the sum of the REN’s should not exceed five (5.0).
To be certain of the number of devices that may be connected to the line, as determined by the total REN’s,
contact the telephone company to determine the maximum REN for the calling area.

4. If this equipment causes harm to the telephone network, the telephone company will notify you in advance
that temporary discontinuance of service may be required. But if advance notice isn’t practical, the telephone
company will notify the customer as soon as possible. Also, you will be advised of your right to file a
complaint with the FCC if you believe it is necessary .

5. The telephone company may make changes in its facilities, equipment, operations, or procedures that
could affect the operation of the equipment. If this happens, the telephone company will provide advance
notice in order for you to make necessary modifications in order to maintain uninterrupted service.

6. If trouble is experienced with this equipment (the model of which is indicated below) please contact Multi­Tech Systems, Inc., at the address shown below for details of how to have repairs made. If the equipment is
causing harm to the telephone network, the telephone company may request that you remove the equipment
from the network until the problem is resolved.

MTPSR3-200

55

ProxyServer User Guide

7. No repairs are to be made by you. Repairs are to be made only by Multi-Tech Systems or its licensees.
Unauthorized repairs void registration and warranty .

8. This equipment cannot be used on public coin service provided by the telephone company. Connection to
Party Line Service is subject to state tariffs. (Contact the state public utility commission, public service
commission or corporation commission for information.)

9. If so required, this equipment is hearing-aid compatible.
Manufacturer: Multi-Tech Systems, Inc.

Trade name: ProxyServer 200-Series
Model Numbers: MTPSR3-200
FCC Registration Number: AU7USA-24994-M5-DE
Ringer Equivalence: 0.6B
Modular Jack (USOC): RJ11
Service Center in U.S.A.: Multi-Tech Systems Inc.

2205 Woodale Drive
Mounds View , MN 55112
[phone] [phone]
[phone] FAX

Exhibit J (Consumer Instructions)

This equipment complies with part 68 of the Federal Communications Commission Rules. On the
outside surface of this equipment is a label that contains, among other information, the FCC
registration number. This information must be provided to the telephone company.

As indicated below, the suitable jack (Universal Service Order Code connecting arrangement) for this
equipment is shown. If applicable, the facility interface codes (FIC) and service order codes (SOC)
are shown.

An FCC-compliant telephone cord and modular plug is provided with this equipment. This equipment
is designed to be connected to the telephone network or premises wiring using a compatible modular
jack which is Part 68 compliant. See installation instructions for details.

If this equipment causes harm to the telephone network, the telephone company will notify you in
advance that temporary discontinuance of service may be required. But if advance notice is not
practical, the telephone company will notify the customer as soon as possible. Also, you will be
advised of your right to file a complaint with the FCC if you believe it is necessary.

The telephone company may make changes in its facilities, equipment, operations, or procedures
that could affect the operation of the equipment. If this happens, the telephone company will provide
advance notice in order for you to make necessary modifications in order to maintain uninterrupted
service.

If trouble is experienced with this equipment (the model of which is indicated below) please contact
Multi-Tech Systems, Inc. at the address shown below for details of how to have repairs made. If the
equipment is causing harm to the network, the telephone company may request you to remove the
equipment from the network until the problem is resolved.

56

MTPSR3-200

No repairs are to be made by you. Repairs are to be made only by Multi-Tech Systems or its
licensees. Unauthorized repairs void registration and warranty.

Manufacturer: Multi-Tech Systems, Inc.
Trade Name: ProxyServer 200-Series
Model Number: MTPSR3-200
FCC Registration Number: AU7USA-24994-M5-DE
Ringer Equivalence Number: 0.6B
Modular Jack (USOC): RJ11
Service Center in USA: Multi-Tech Systems, Inc.

2205 Woodale Drive
Mounds View , MN 55112
[phone] Fax [phone]

Canadian Limitations Notice

Notice: The ringer equivalence number (REN) assigned to each terminal device provides an

indication of the maximum number of terminals allowed to be connected to a telephone interface. The
termination of an interface may consist of any combination of devices subject only to the requirement
that the sum of the ringer equivalence numbers of all the devices does not exceed 5.

Notice: The Industry Canada label identifies certificated equipment. This certification means that the
equipment meets certain telecommunications network protective, operational and safety
requirements. The Industry Canada does not guarantee the equipment will operate to the user’s
satisfaction.

Appendices

Before installing this equipment, users should ensure that it is permissible to be connected to the
facilities of the local telecommunications company . The equipment must also be installed using an
acceptable method of connection. The customer should be aware that compliance with the above
conditions may not prevent degradation of service in some situations.

Repairs to certified equipment should be made by an authorized Canadian maintenance facility
designated by the supplier. Any repairs or alterations made by the user to this equipment, or
equipment malfunctions, may give the telecommunications company cause to request the user to
disconnect the equipment.

Users should ensure for their own protection that the electrical ground connections of the power
utility , telephone lines and internal metallic water pipe system, if present, are connected together. This
precaution may be particularly important in rural areas.

Caution: Users should not attempt to make such connections themselves, but should contact the
appropriate electric inspection authority , or electrician, as appropriate.

This digital apparatus does not exceed the Class B limits for radio noise emissions from digital
apparatus set out in the Radio Interference Regulation of the Canadian Department of
Communications.

Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites
applicables aux appareils numériques de la classe B prescrites dans le Règlement sur le brouillage
radioélectrique édicté par le ministère des Communications du Canada.

Ringer Equivalence Number

Notice: The ringer equivalence number (REN) asigned to each terminal device provides an indication

of the maximum number of terminals allowed to be connected to a telephone interface. The
termination on an interface may consist of any combination of devices subject only to the requirement
that the sum of the ringer equivalence numbers of all the devices does not exceed 5.

MTPSR3-200

57

ProxyServer User Guide

Modem CE Mark EMC and Safety Compliance

The CE mark is affixed to the enclosed MultiTech product to confirm compliance with the following European
Community Directives:

Council Directive 89/336/EEC of 3 May 1989 on the approximation of the laws of Member States relating to
electromagnetic compatibility;

and
Council Directive 73/23/EEC of 19 February 1973 on the harmonization of the laws of Member States relating

to electrical equipment designed for use within certain voltage limits;
both amended by
Council Directive 93/68/EEC of 22 July 1993 on the harmonization of CE marking requirements.

58

MTPSR3-200

Appendices

Appendix D - AT Command Summary

This section summarizes your modem’s AT commands. For detailed information on the commands,
download ZPXHELP.EXE from the Multi-Tech BBS (see “Call the Multi-Tech BBS” in Chapter 3).

AT Commands

Command: +++AT<CR> Escape Sequence
Values: n/a
Description: Puts the modem in command mode (and optionally issues a command) while remaining online.

Type +++AT and up to ten command characters, then press ENTER. Used mostly to issue the
hang-up command: +++ATH<CR>.

Command: AT Attention Code
Values: n/a
Description: The attention code precedes all command lines except A/ and the escape sequence.

Command: ENTER Key
Values: n/a
Description: Press the ENTER key to execute most commands.

Command: $ Detect AT&T's "call card" tone
Values: n/a
Description: This symbol placed in dialing string enables the modem to detect AT&T's "call card" tones to

access user's calling card when originating an on-line connection--

Command: A Answer
Values: n/a
Description: Answer an incoming call before the final ring.

Command: A/ Repeat Last Command
Values: n/a
Description: Repeat the last command string. Do not precede this command with AT. Do not press ENTER to

execute.

Command: B
Values:
Default: 1 and 16
Description: B0 Select ITU-T V.22 mode when modem is at 1200 bps.

Command: C
Values:
Default: 1
Description: C0 Transmit carrier always off. (Not supported.)

n

Communication Standard Setting

n

= 0–3, 15, 16

B1 Select Bell 212A when modem is at 1200 bps.
B2 Deselect V.23 reverse channel (same as B3).
B3 Deselect V.23 reverse channel (same as B2).
B15 Select V.21 when the modem is at 300 bps.
B16 Select Bell 103J when the modem is at 300 bps.

n

Carrier Control

n =

1

C1 Normal transmit carrier switching (included for backward compatibility with some software).

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ProxyServer User Guide

Command: D
Values:
Default: none
Description: Dial telephone number s, where s may up to 40 characters long and include the 0–9, *, #, A, B, C,

s

Dial

s

= dial string (phone number and dial modifiers)

and D characters, and the L, P, T, V, W, S, comma (,), semicolon (;), !, @, ^ and $ dial string
modifiers.

Dial string modifiers:

L Redial last number. (Must be placed immediately after ATD.)
P Pulse-dial following numbers in command .
T Tone-dial following numbers in command (default).
V Switch to speakerphone mode and dial the following number. Use ATH command to hang up.
W Wait for a new dial tone before continuing to dial. (X2, X4, X5, X6, or X7 must be selected.)

S Dial a telephone number previously stored using the &Zn=x command (see &Zn=x command

for further information). The range of n is 0-3.

, Pause during dialing for time set in register S8.
; Return to command mode after dialing. (Place at end of dial string.)
! Hook flash. Causes the modem to go on-hook for one-half second, then off-hook again.
@ Wait for quiet answer. Causes modem to wait for a ringback, then 5 seconds of silence, before

processing next part of command. If silence is not detected, the modem returns a NO ANSWER
code.

$ AT&T's "call card" tones detection.
^ Disable data calling tone transmission.

Command: DS=
Values:
Default: none
Description: Dial a number previously stored in directory number n by the

n

Dial Stored Telephone Number

n

= 0–3

Example: ATDS=3

&Zn=x

command .

Command: E
Values:
Default: 1
Description: E0 Do not echo keyboard input to the terminal.

Command: F
Values:
Default: 1
Description: F0 Enable online data character echo. (Not supported.)

Command: H
Values:
Default: 0
Description: H0 Go on-hook to hang up.

Command: I
Values:
Default: None
Description: I0 Display default speed and controller firmware version.

n

Echo Command Mode Characters

n

= 0 or 1

E1 Do echo keyboard input to the terminal.

n

Echo Online Data Characters

n =

1

F1 Disable online data character echo (included for backward compatibility with some software).

n

Hook Control

n

= 0 or 1

H1 Go off-hook to make the phone line busy.

n

Information Request

n

= 0–4, 9, 11

I1 Calculate and display ROM checksum (e.g., “12AB”).
I2 Check ROM and verify the checksum, displaying
I3 Display default speed and controller firmware version.
I4 Display firmware version for data pump (e.g., “94”).
I9 Display country code (e.g., “NA Ver. 1”).
I11 Display Diagnostic Information for the last Modem Connection (i.e., DSP and Firmware version,

Link Type, Line Speed, Serial Speed, Type of Error Correction/Data Compression, Number of past
Retrains,etc.)

OK

or

ERROR

.

60

MTPSR3-200

Appendices

Command: L
Values:
Default: 2
Description: L0 Select low volume.

Command: M
Values:
Default: 1
Description: M0 Speaker always off.

Command: N
Values:
Default: 1
Description: N0 Modem performs handshake only at communication standard specified by S37 and the

Command: O Return Online to Data Mode
Values: 0, 1, 3
Default: None
Description: O0 Exit online command mode and return to data mode.

n

Monitor Speaker Volume

n

= 0, 1, 2, or 3

L1 Select low volume.
L2 Select medium volume.
L3 Select high volume.

n

Monitor Speaker Mode

n

= 0, 1, 2, or 3

M1 Speaker on until carrier signal detected.
M2 Speaker always on when modem is off-hook.
M3 Speaker on until carrier is detected, except while dialing.

n

Modulation Handshake

n

= 0 or 1

command.

N1 Modem begins handshake at communication standard specified by S37 and the

During handshake, fallback to a lower speed can occur.

O1 Issue a retrain and return to online data mode.
O3 Issue a rate renegotiation and return to data mode.

B

command.

B

Command: Q
Values:
Default: 0
Description: Q0 Enable result codes.

Command: S
Values:
Default: None
Description: Set value of register S

Command: S
Values:
Default: None
Description: Read value of register Sr and display value in 3-digit decimal form.

Command: V
Values:
Default: 1
Description: V0 Displays result codes as digits (terse response).

n

Result Codes Enable/Disable

n

= 0 or 1

Q1 Disable result codes.

r=n

Set Register Value

r

= S-register number; n varies

r

to value of n, where n is entered in decimal format.

r

? Read Register Value

r

= S-register number

n

Result Code Format

n

= 0 or 1

V1 Displays result codes as words (verbose response).

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ProxyServer User Guide

Command: X
Values:
Default: 4
Description: X0 Basic result codes (

Command: Y
Values:
Default: 0
Description: Y0 Disable sending or responding to long space break signal on disconnect.

Command: Z
Values:
Default: None
Description: Z0 Reset modem to profile saved by the last

Command: &B
Values:
Default: 1
Description: &B0 Disable V.32 auto retrain. (Not supported.)

n

Result Code Selection

n

= 0–7

e.g., CONNECT

X1 Extended result codes (

for dial tone or busy signal.
X2 Extended result codes with
X3 Extended result codes with
X4 Extended result codes with
X5 Extended result codes with
X6 Extended result codes with
X7 Basic result codes with

n

Long Space Disconnect

n

= 0

Y1 Enable sending or responding to long space break signal on disconnect. (Not supported.)

n

Modem Reset

n

= 0 or 1

Z1 Same as Z0.

n

V.32 Auto Retrain

n

= 1

&B1 Enable V.32 auto retrain.

CONNECT 56000 V42bis, CONNECT 33600 V42bis

NO DIALTONE

BUSY
NO DIALTONE
NO DIALTONE
NO DIALTONE

NO DIALTONE

); does not look for dial tone or busy signal.

; does not look for busy signal.

; does not look for dial tone.

and

BUSY

.

and

BUSY

.

and

BUSY

.

and

BUSY

.

&W

command.

, etc.); does not look

Command: &CnData Carrier Detect (DCD) Control
Values:
Default: 1
Description: &C0 Force Data Carrier Detect signal high.

&C1 Let Data Carrier Detect follow carrier signal.

Command: &D
Values:
Default: 2
Description: &D0 Modem ignores DTR signal.

&D1 When DTR drops while in online data mode, the modem enters command mode, issues an OK,

&D2 When DTR drops while in online data mode, the modem hangs up.
&D3 When DTR drops, the modem hangs up and resets as if an ATZ command were issued.

Command: &F
Values:
Default: None
Description: &F0 Load factory settings as active configuration.

Command: &G
Values:
Default: 0
Description: &G0 Disable guard tone.

&G1 Enable 550 Hz guard tone.
&G2 Enable 1800 Hz guard tone.

n

= 0 or 1

n

Data Terminal Ready (DTR) Control

n

= 0, 1, 2, or 3

and remains connected.

n

Load Factory Default Settings

n

= 0

n

V.22bis Guard Tone Control

n

= 0, 1, or 2

*: The

&G

command is not used in North America.

62

MTPSR3-200

Command: &JnAuxiliary Relay Control

Values: n

Default: 0
Description: &J0 The auxiliary relay is never closed.

&J1 Not supported—responds ERROR.

Command: &KnLocal Flow Control Selection
Values:
Defaults: 3
Description: &K0 Flow control disabled.

&K3 Enable CTS/RTS hardware flow control.
&K4 Enable XON/XOFF software flow control.

= 0

n

= 0, 3, or 4

Appendices

Command: &M
Values:
Defaults: 0
Description: &M0 Asynchronous mode.

Command: &QnAsynchronous Communications Mode
Values:
Defaults: 5
Description: &Q0 Asynchronous with data buffering. Same as

Command: &S
Values:
Default: 0
Description: &S0 Force DSR high (on).

Command: &T
Values:
Default: None
Description: &T0 Abort. Stop any test in progress.

n

Communications Mode

n

= 0

&M1 Reserved—responds ERROR.

n

= 0, 5, or 6

&Q5 Error control with data buffering. Same as
&Q6 Asynchronous with data buffering. Same as

n

Data Set Ready (DSR) Control

n

= 0 or 1

&S1 Let DSR follow CD.

n

Self-Test Commands

n

= 0, 1, 3 or 6

&T1 Local analog loop test.
&T3 Local digital loopback test.
&T6 Remote digital loopback test.

\N3

\N0

\N0

.

.

.

Command: &V View Current Configuration
Values: n/a
Description: Displays the active modem settings.

Command: &W
Values:
Default: None
Description: &W0 Store active modem settings in NVRAM; load them at power-on or following the ATZ command

Command: &Y
Values:
Default: 0
Description: &Y0 Select stored configuration 0 on power-up. (For backward compatibility with some software.)

Command: &Zn=xStore Telephone Number
Values:

Default: None
Description: Stores telephone dial string

n

Store Current Configuration

n

= 0

instead of loading the factory defaults from ROM.

n

Select Stored Configuration for Hard Reset

n

= 0

&Y1 Not supported—responds ERROR.

n

= 0, 1, 2, or 3

x = Dialing string

ATDS=n

.

MTPSR3-200

x

in memory location n. Dial the stored number using the command

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Command: \G
Values:
Default: 0
Description: \G0 Returns an

Command: \J
Values:
Default: 0
Description: \J0 Enable data buffer—serial port speed is independent of connect speed.

Command: \K
Values:
Default: 5
Description: \K5 Modem sends break signal received from the DTE to the remote modem.

Command: \N
Values:
Default: 3
Description: \N0 Non-error correction mode with data buffering (same as

n

Modem Port Flow Control

n

= 0

OK

for backward compatibility with some software.

\G1 Not supported—responds ERROR.

n

Data Buffer Control

n

= 0

\J1 Not supported—responds ERROR.

n

Set Break Control

n

= 5

n

Error Correction Mode Selection

n

= 0–5, or 7

\N1 Direct mode.
\N2 MNP reliable mode.
\N3 V.42/MNP auto-reliable mode.
\N4 V.42 reliable mode.
\N5 V.42, MNP, or non-error correction (same as
\N7 V.42, MNP, or non-error correction (same as

\N3
\N3

&Q6

).

).
).

n

Command: \Q
Values:
Default: 3
Description: \Q0 Disable flow control (same as

\Q1 XON/XOFF software flow control (same as
\Q2 CTS-only flow control. Not supported—responds ERROR.
\Q3 RTS/CTS hardware flow control (same as

Command: \T
Values:
Default: n/a
Description: \Tn Inactivity timer setting contingent on either \T value or S-Register S30 value (e.g.,

Command: \V
Values:
Default: 1
Description: \V0 Disable protocol result code appended to DCE speed.

\V1 Enable protocol result code appended to DCE speed.

Command: \X
Values:
Defaults: 0
Description: \X0 Respond to and discard XON/XOFF characters.

\X1 Not supported—responds ERROR.

Command: -C
Values:
Defaults: 0
Description: -C0 Disable V.25 data calling tone.

-C1 Enable V.25 data calling tone.

Local Flow Control Selection

n

= 0, 1, or 3

&K0

).

&K4

).

&K3

).

n

Inactivity Timer

n

= 0–255

AT\T45&W0<cr> configures in parallel ATS30=45&W0<cr>), and vice versa.

n

Protocol Result Code

n

= 0 or 1

n

XON/XOFF Pass-Through

n

= 0 or 1

n

Data Calling Tone

n

= 0 or 1

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Appendices

Command: %B View Numbers in Blacklist
Values: n/a
Description: If blacklisting is in effect, this command displays the numbers for which the last call attempted in

the previous two hours failed. In countries that do not require blacklisting, the ERROR result code
appears.

Command: %C
Values:
Default: 1
Description: %C0 Disable V.42bis/MNP 5 data compression.

Command: +ES=6 Enable Synchronous Buffered Mode
Values: n/a
Description: Allows an H.324 video application direct access to the synchronous data channel. On underflow,

Command: &&S Speaker Codec Loopback
Values: n/a
Description: Provides a loopback from the microphone to the speaker.

Command: %T94 Testing External RAM
Values: n/a
Description: This command is used for testing the external RAM. Enter AT%T94<cr> to determine the status

Command: %T125 Testing DSP 56K Code Version/Checksum
Values: n/a
Description: Entering AT%T125<cr> tests the DSP56K code version and checksum running in external RAM.

n

Data Compression Control

n

= 0 or 1

%C1 Enable V.42bis/MNP 5 data compression.

the modem sends HDLC flag idle (0x7E) to the remote modem. This special error correction mode
is overridden by any of the following commands:
allowed value.

&F, &M, &Q

, and \N.

+ES = ?

shows the only

For testing and debugging only.

of external RAM. The response you should receive will be either "FAIL" or "PASS"

Upon issuing this command the user may then issue ATI4<cr> to get DSP version or ATI1<cr> to
get DSP checksum in RAM.
Entering AT%T124<cr> tests the DSP56K code version and checksum running in internal ROM.
Upon issuing this command the user may then issue ATI4<cr> to get DSP version or ATI1<cr> to
get DSP checksum in ROM.

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Glossary of Terms

ProxyServer User Guide

A

Access: The T1 line element made up of two pairs of wire that the telephone company brings to the customer premises.

The Access portion ends with a connection at the local telco (LEC or RBOC).
Accunet Spectrum of Digital Services (ASDS): The AT&T 56K bps leased (private) line service. Similar to services of MCI

and Sprint. ASDS is available in nx56/64K bps, where n=1, 2, 4, 6, 8, 12.
ACK (ACKnowledgement code) (pronounced “ack”): A communications code sent from a receiving modem to a

transmitting modem to indicate that it is ready to accept data. It is also used to acknowledge the error-free receipt of
transmitted data. Contrast with NAK.

Adaptive Differential Pulse Code (ADCPM): In multimedia applications, a technique in which pulse code modulation
samples are compressed before they are stored on a disk. ADCPM, an extension of the PCM format, is a standard
encoding format for storing audio information in a digital format. It reduced storage requirements by storing differences
between successive digital samples rather than full values.

Address: A numbered location inside a computer. It’s how the computer accesses its resources, like a video card, serial
ports, memory, etc.

AMI line coding: One of two common methods of T1 line coding (with B8ZS). AMI line coding places restrictions on user
data (B8ZS does not).

Analog signal: A waveform which has amplitude, frequency and phase, and which takes on a range of values between its
maximum and minimum points.

Analog Transmission: One of two types of telecommunications which uses an analog signal as a carrier of voice, data,
video, etc. An analog signal becomes a carrier when it is modulated by altering its phase, amplitude and frequency to
correspond with the source signal. Compare with digital transmission.

Application Program Interface (API): A software module created to allow dissimilar, or incompatible applications programs
to transfer information over a communications link. APIs may be simple or complex; they are commonly required to link PC
applications with mainframe programs.

ASCII (American Standard Code for Information Interchange) (pronounced “askey”): A binary code for data that is
used in communications and in many computers and terminals. The code is used to represent numbers, letters, punctuation
and control characters. The basic ASCII code is a 7-bit character set which defines 128 possible characters. The extended
ASCII file provides 255 characters.

Asynchronous Transfer Mode (ATM): A very high-speed method of transmission that uses fixed-size cells of 53 bytes to
transfer information over fiber; also known as cell relay.

AT Commands: A standard set of commands used to configure various modem parameters, establish connections and
disconnect. The “AT” is used to get the “attention” of the modem before the actual command is issued.

Availability: The measure of the time during which a circuit is ready for use; the complement of circuit “outage” (100%
minus % outage = % available).

B

B7ZS (Bipolar 7 Zero Suppression) line coding: One method of T1 line coding (see also “B8ZS” and “AMI”). B7ZS line

coding does not place restrictions on user data (AMI does).
B8ZS (Bipolar 8 Zero Suppression) line coding: One of two common methods of T1 line coding (with AMI). B8ZS line

coding does not place restrictions on user data (AMI does). A coding method used to produce 64K bps “clear” transmission.
(See also “B7ZS” and “AMI” line coding)

Backbone: 1. A set of nodes and their interconnecting links providing the primary data path across a network. 2. In a local
area network multiple-bridge ring configuration, a high-speed link to which the rings are connected by means of bridges. A
backbone may be configured as a bus or as a ring. 3. In a wide area network, a high-speed link to which nodes or data
switching exchanges (DSEs) are connected. 4. A common distribution core that provides all electrical power, gases,
chemicals, and other services to the sectors of an automated wafer processing system.

Background: An activity that takes place in the PC while you are running another application. In other words, the active
user interface does not correspond to the ‘background’ task.

Bandwidth: The transmission capacity of a computer channel, communications line or bus. It is expressed in cycles per
second (hertz), the bandwidth being the difference between the lowest and highest frequencies transmitted. The range of
usable frequencies that a transmission medium will pass without unacceptable attenuation or distortion. Bandwidth is a
factor in determining the amount of information and the speed at which a medium can transmit data or other information.

Backward Explicit Congestion Notification (BECN): A bit that tells you that a certain frame on a particular logical
connection has encountered heavy traffic. The bit provides notification that congestion-avoidance procedures should be
initiated in the opposite direction of the received frame. See also FECN (Forward Explicit Congestion Notification).

68

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Glossary

Basic Rate Interface (BRI): An ISDN access interface type comprised of two B-channels each at 64K bps and one D-

channel at 64K bps (2B+D).
Bell Operating Companies (BOC): The family of corporations created during the divestiture of AT&T. BOCs are

independent companies which service a specific region of the US. Also called Regional Bell Operating Companies
(RBOCs).

Bell Pub 41450: The Bell publication defining requirements for data format conversion, line conditioning, and termination
for direct DDS connection.

Bell Pub 62310: The Bell publication defining requirements for data format conversion, line conditioning, and termination
for direct DDS connection.

Binary Synchronous Communication (BSC): A form of telecommunication line control that uses a standard set of
transmission control characters and control character sequences, for binary synchronous transmission of binary-coded data
between stations.

Bit (Binary digIT): A bit is the basis of the binary number system. It can take the value of 1 or 0. Bits are generally
recognized as the electrical charge generated or stored by a computer that represent some portion of usable information.

Bit Error Rate Test (BERT): A device or routine that measures the quality of data transmission. A known bit pattern is
transmitted, and the errors received are counted and a BER (bit error rate) is calculated. The BER is the ratio of received
bits in error relative to the total number of bits received, expressed in a power of 10.

Bit robbing: The use of the least significant bit per channel in every sixth frame for signaling. The line signal bits “robbed”
from the speech part conveys sufficient pre-ISDN telephony signaling information with the remaining line signal bits
providing sufficient line signaling bits for recreating the original sound. See “robbed bit signaling”.

Blue Alarm: An error indication signal consisting of all 1s indicating disconnection or attached device failure. Contrast “Red
Alarm” and “Yellow Alarm”.

Bps (bits per second): A unit to measure the speed at which data bits can be transmitted or received. Bps differs from
baud when more than one bit is represented by a single cycle of the carrier.

Bridges: 1. A functional unit that interconnects two local area networks that use the same logical link protocol but may use
different medium access control protocols. 2. A functional unit that interconnects multiple LANs (locally or remotely) that use
the same logical link control protocol but that can use different medium access control protocols. A bridge forwards a frame
to another bridge based on the medium access control (MAC) address. 3. In the connection of local loops, channels, or
rings, the equipment and techniques used to match circuits and to facilitate accurate data transmission.

Buffer: A temporary storage register or Random Access Memory (RAM) used in all aspects of data communications which
prevents data from being lost due to differences in transmission speed. Keyboards, serial ports, muxes and printers are a
few examples of the devices that contain buffers.

Bus: A common channel between hardware devices either internally between components in a computer, or externally
between stations in a communications network.

Byte: The unit of information a computer can handle at one time. The most common understanding is that a byte consists
of 8 binary digits (bits), because that’s what computers can handle. A byte holds the equivalent of a single character (such
as the letter A).

C

Call Setup Time: The time to establish a circuit-switched call between two points. Includes dialing, wait time, and CO/long

distance service movement time.
Carrier Group Alarm (CGA): A T1 service alarm generated by a channel bank when an OOF condition occurs for a

predefined length of time (usually 300mS to 2.5 seconds). The CGA causes the calls using a trunk to be dropped and for
trunk conditioning to be applied.

Carrier signal: An analog signal with known frequency, amplitude and phase characteristics used as a transport facility for
useful information. By knowing the original characteristics, a receiver can interpret any changes as modulations, and
thereby recover the information.

CCITT (Consultative Committee for International Telephone and Telegraph): An advisory committee created and
controlled by the United Nations and headquartered in Geneva whose purpose is to develop and to publish
recommendations for worldwide standardization of telecommunications devices. CCITT has developed modem standards
that are adapted primarily by PTT (post, telephone and telegraph) organizations that operate telephone networks of
countries outside of the U.S. See also ITU.

Central Office (CO): The lowest, or most basic level of switching in the PSTN (public switched telephone network). A
business PABX or any residential telephone connects to the PSTN at a central office.

Centrex: A multi-line service offered by operating telcos which provides, from the telco CO, functions and features
comparable to those of a PBX for large business users. See also “Private Branch Exchange”, “Exchange”.

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Channel: A data communications path between two computer devices. Can refer to a physical medium (e.g., UTP or coax),

or to a specific carrier frequency.
Channel Bank: A device that acts as a converter, taking the digital signal from the T1 line into a phone system and

converting it to the analog signals used by the phone system. A channel bank acts as a multiplexer, placing many slow­speed voice or data transactions on a single high-speed link.

Circuit-switched Network: A technology used by the PSTN that allocates a pair of conductors for the exclusive use of one
communication path. Circuit switching allows multiple conversations on one talk path only if the end-users multiplex the
signals prior to transmission.

Circuit Switching: The temporary connection of two or more communications channels using a fixed, non-shareable path
through the network. Users have full use of the circuit until the connection is terminated.

Clear Channel: A transmission path where the full bandwidth is used (i.e., no bandwidth needed for signaling, carrier
framing or control bits). A 64K bps digital circuit usually has 8K bps used for signaling. ISDN has two 64K bps circuits, and a
16K bps packet service of which part is used for signaling on the 64K channels.

Client-Server: In TCP/IP, the model of interaction in distributed data processing in which a program at one site sends a
request to a program at another site and awaits a response. The requesting program is called a client; the answering
program is called a server.

Cluster Controller: A device that can control the input/output operations of more than one device connected to it. A cluster
controller may be controlled by a program stored and executed in the unit, or it may be entirely controlled by hardware.

Committed Burst Size: The maximum number of bits that the frame relay network agrees to transfer during any
measurement interval.

Committed Information Rate (CIR): An agreement a customer makes to use a certain minimum data transmission rate (in
bps). The CIR is part of the frame relay service monthly billing, along with actual usage, that users pay to their frame relay
service provider.

Compression: 1. The process of eliminating gaps, empty fields, redundancies, and unnecessary data to shorten the length
of records or blocks. 2. In SNA, the replacement of a string of up to 64-repeated characters by an encoded control byte to
reduce the length of the data stream to the LU-LU session partner. The encoded control byte is followed by the character
that was repeated (unless that character is the prime compression character). 3. In Data Facility Hierarchical Storage
Manager, the process of moving data instead of allocated space during migration and recall in order to release unused
space. 4. Contrast with decompression.

COMx Port: A serial communications port on a PC.
congestion: A network condition where there is too much data traffic. The ITU I.233 standard defines congestion

managemennt in terms of speed and burstiness.
congestion notification: The function in frame relay that ensures that user data transmitted at a rate higher than the CIR

are allowed to slow down to the rate of the available network bandwidth.
Consecutive Severely Errored Seconds (CSES): An error condition that occurs when from 3 to 9 SES (Severely Errored

Seconds) are logged consecutively.
Customer Premise Equipment (CPE): The generic term for data comm and/or terminal equipment that resides at the user

site and is owned by the user with the following exclusions: Over voltage protection equipment, inside wiring, coin operated
or pay telephones, “company-official” equipment, mobile telephone equipment, “911” equipment, equipment necessary for
the provision of communications for national defense, or multiplexing equipment used to deliver multiple channels to the
customer.

D

D4: the T1 4th generation channel bank.
D4 channelization: Refers to the compliance with AT&T TR 62411 for DS1 frame layout.
D4 framing: The T1 format for framing in AT&T D-Series channel banks, in which there are 12 separate 193-bit frames in a

super-frame. A D4 framing bit is used to identify the channel and the signaling frame. Signalling for voice channels is
carried in-band for every channel, along with the encoded voice. See “robbed-bit signaling”.

Data Communications Equipment (DCE): Any device which serves as the portal of entry from the user equipment to a
telecommunications facility. A modem is a DCE for the telephone network (PSTN) that is commonly on site at the user’s
premises. Packet Switched Networks have another level of DCE which is most often located at a central office.

Data Link Connection Identifier (DLCI): One of the six components of a frame relay frame. Its purpose is to distinguish
separate virtual circuits across each access connection. Data coming into a frame relay node is thus allowed to be sent
across the interface to the specified “address”. The DLCI is confirmed and relayed to its destination, or if the specification is
in error, the frame is discarded.

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Glossary

Dataphone Digital Service (DDS): A private line digital service that offers 2400, 4800, 9600 and 56K bps data rates on an

inter-LATA basis by AT&T and on an intra-LATA basis by the BOCs.
Data Service Unit (DSU): A device that provides a digital data service interface directly to the data terminal equipment. The

DSU provides loop equalization, remote and local testing capabilities, and a standard EIA/CCITT interface.

Dedicated Line: A communication line that is not switched. The term leased line is more common.
Default: This is a preset value or option in software packages, or in hardware configuration, that is used unless you specify

otherwise.

Device driver: Software that controls how a computer communicates with a device, such as a printer or mouse.
Digital Cross-connect System (DCS): The CO device which splits and redistributes the T1 bandwidth. the DCS takes time

slots from various T1 lines and alters them to provide the needed connectivity. DCS connections are made with software at
an administrator’s workstation.

Digital Data: Information represented by discrete values or conditions (contrast “Analog Data”).
Digital Loopback: A technique used for testing the circuitry of a communications device. Can be initiated locally, or

remotely (via a telecommunications device). The tested device decodes and encodes a received test message, then echoes
the message back. The results are compared with the original message to determine if corruption occurred en route.

Digital PBX: A Private Branch Exchange that operates internally on digital signals. See also “Exchange”.
Digital Service, level 0 (DS0): The world-wide standard speed (64K bps) for digital voice conversation using PCM (pulse

coded modulation).
Digital Service, level 1 (DS1): The 1.544M bps voice standard (derived from an older Bell System standard) for digitized

voice transmission in North America. The 1.544M bps consists of 24 digitally-encoded 64K bps voice channels (north
America) and 2.048M bps (30 channels) elsewhere.

Digital Signal: A discrete or discontinuous signal (e.g., a sequence of voltage pulses). Digital devices, such as terminals
and computers, transmit data as a series of electrical pulses which have discrete jumps rather than gradual changes.

Digital Signaling Rates (DSn): A hierarchical system for transmission rates, where “DS0” is 64K bps (equivalent to ISDN B
channel), and DS1 is 1.5 Mbps (equivalent to ISDN PRI).

Digital Transmission: A method of electronic information transmission common between computers and other digital
devices. Analog signals are waveforms: a combination of many possible voltages. A computer’s digital signal may be only
“high” or “low” at any given time. Therefore, digital signals may be “cleaned up” (noise and distortion removed) and
amplified during transmission.

Digitize: To convert an analog signal to a digital signal.
DIP switch (pronounced “dip switch”): A set of tiny toggle switches, built into a DIP (dual in-line package), used for

setting configurable parameters on a PCB (printed circuit board).
Driver: A software module that interfaces between the Operating System and a specific hardware device (e.g., color

monitors, printers, hard disks, etc.). Also known as a device driver.
Drop and Insert: The process where a portion of information carried in a transmission system is demodulated (“Dropped”)

at an intermediate point and different information is included (“Inserted”) for subsequent transmission.
DTE (Data Terminal Equipment): A term used to include any device in a network which generates, stores or displays user

information. DTE is a telecommunications term which usually refers to PCs, terminals, printers, etc.

DTMF (Dual-Tone MultiFrequency): A generic push-button concept made popular by AT&T TouchTone.

E

E&M: A telephony trunking system used for either switch-to-switch, or switch-to-network, or computer/telephone system-to-

switch connection.
EIA: The Electronics Industries Association is a trade organization in Washington, DC that sets standards for use of its

member companies. (See RS-232, RS-422, RS530.)
Encapsulation: A technique used by network-layer protocols in which a layer adds header information to the protocol data

unit from the preceding layer. Also used in “enveloping” one protocol inside another for transmission. For example, IP inside
IPX.

Errored Seconds (ES): Any second of operation that all 1.544M bits are not received exactly as transmitted. Contrast
“Error Free Seconds”.

Error Free Seconds (EFS): Any second of operation that all 1.544M bits are received exactly as transmitted. Contrast
“Errored Seconds”.

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ESF Error Event: A T1 error condition that is logged when a CRC-6 error or an out-of-frame (OOF) error occurs.
Ethernet: A 10-megabit baseband local area network that allows multiple stations to access the transmission medium at will

without prior coordination, avoids contention by using carrier sense and deference, and resolves contention by using
collision detection and transmission. Ethernet uses carrier sense multiple access with collision detection (CSMA/CD).

Excess Zeros: A T1 error condition that is logged when more than 15 consecutive 0s or fewer than one 1 bit in 16 bits
occurs.

Exchange: A unit (public or private) that can consist of one or more central offices established to serve a specified area. An
exchange typically has a single rate of charges (tariffs) that has previously been approved by a regulatory group.

Exchange Area: A geographical area with a single uniform set of charges (tariffs), approved by a regulatory group, for
telephone services. Calls between any two points within an exchange area are local calls. See also “Digital PBX”, “PBX”.

Exchange Termination (ET): The carrier’s local exchange switch. Contrast with “Loop Termination - LT”.
Explicit Congestion Management: The method used in frame relay to notify the terminal equipment that the network is

overly busy. The use of FECN and BECN is called explicit congestion management. Some end-to-end protocols use FECN
or BECN, but usually not both options together. With this method, a congestion condition is identified and fixed before it
becomes critical. Contrast with “implicit congesion”.

Extended Super Frame (ESF): One of two popular formats for framing bits on a T1 line. ESF framing has a 24-frame
super-frame, where robbed bit signaling is inserted in the LSB (bit 8 of the DS-0 byte) of frames 6, 12, 18 and 24. ESF has
more T1 error measurement capabilities than D4 framing. Both ESF and B8ZS are typically offered to provide clear channel
service.

F

Failed Seconds: A test parameter where the circuit is unavailable for one full second.
Failed Signal: A T1 test parameter logged when there are more than 9 SES (Severely Errored Seconds).
Fax (facsimile): Refers to the bit-mapped rendition of a graphics-oriented document (fax) or to the electronic transmission

of the image over telephone lines (faxing). Fax transmission differs from data transmission in that the former is a bit­mapped approximation of a graphical document and, therefore, cannot be accurately interpreted according to any character
code.

Firmware: A category of memory chips that hold their content without electrical power, they include ROM, PROM, EPROM
and EEPROM technologies. Firmware becomes “hard software” when holding program code.

Foreground: The application program currently running on and in control of the PC screen and keyboard. The area of the
screen that occupies the active window. Compare with “background”.

Fractional T1 (FT1): A digital data transmission rate between 56K bps (DS0 rate) and 1.544M bps (the full T1 rate - in
North America). FT1 is typically provided on 4-wire (two copper pairs) UTP. Often used for video conferencing, imaging and
LAN interconnection due to its low cost and relatively high speed. FT1 rates are offered in 64K bps multiples, usually up to
768K bps.

Frequency: A characteristic of an electrical or electronic signal which describes the periodic recurrence of cycles.
Frequency is inversely proportional to the wavelength or pulse width of the signal (i.e., long wavelength signals have low
frequencies and short wavelength signals yield high frequencies).

Foreign Exchange (FX): A CO trunk with access to a distant CO, allowing ease of access and flat-rate calls anywhere in
the foreign exchange area.

Foreign Exchange Office (FXO): provides local telephone service from a CO outside of (“foreign” to) the subscriber’s
exchange area. In simple form, a user can pick up the phone in one city and receive a tone in the foreign city. Connecting a
POTS telephone to a computer telephony system via a T1 link requires a channel bank configured for the FX connection. To
generate a call from the POTS set to the computer telephony system, a FXO connection must be configured.

Foreign Exchange Station (FXS): See FX, FXO. To generate a call from the computer telephony system to the POTS set,
an FXS connection must be configured.

Forward Explicit Congestion Notification (FECN): A bit that tells you that a certain frame on a particular logical
connection has encountered heavy traffic. The bit provides notification that congestion-avoidance procedures should be
initiatedin the same direction of the received frame. See also BECN (Backward Explicit Congestion Notification).

Frame: A group of data bits in a specific format to help network equipment recognize what the bits mean and how to
process them. The bits are sent serially, with a flag at each end signifying the start and end of the frame.

Frame Relay: A form of packet switching that uses small packets and that requires less error checking than other forms of
packet switching. Frame relay is effective for sending “bursty” data at high speeds (56/64K, 256K, and 1024K bps) over
wide area networks. Frame Relay specifications are defined by ANSI documents ANSI T1.602, T1.606, T1S1/90-175, T1S1/
90-213, and T1S1/90-214. In using frame relay, blocks of information (frames) are passed across a digital network interface
using a “connection number” that is applied to each frame to distinguish between individual frames.

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Glossary

Frame Relay Forum: A non-profit organization of 300+ vendors and service providers, based in Foster City, CA, that are

developing and deploying frame relay equipment.
Frame Relay Implementors Forum: A group of companies supporting a common specification for frame relay connection

to link customer premises equipment to telco network equipment. Their specification supports ANSI frame relay specs and
defines extensions such as local management.

Frame Relay Access Device (FRAD): A piece of equipment that acts as a concentrator or frame assembler/dissassember
that can support multiple protocols and provide basic “routing” functions.

G

Gateway: 1. A functional unit that interconnects two computer networks with different network architectures. A gateway

connects networks or systems of different architectures. A bridge interconnects networks or systems with the same or
similar architectures. 2. A network that connects hosts.

Graphical User Interface (GUI): A type of computer interface consisting of a visual metaphor of a real-world scene, often
of a desktop. Within that scene are icons, representing actual objects, that the user can access and manipulate with a
pointing device.

H

Handshaking: A process that two modems go through at the time of call setup to establish synchronization over the data

communications link. It is a synchronization and negotiation process accomplished by the exchange of predefined, mutually
recognized control codes.

High-level Data Link Control (HDLC): An ISO standard, bit-oriented data communications protocol that provides nearly
error-free data transfers.

I

Hexadecimal: A base 16 numbering system used to represent binary values. Hex uses the numbers 0-9 and the letters A-F:

usually notated by an “h” (e.g., “4CF h”, read “four charley fox, hex”). The result is that one hex digit represents a 4-bit
value.

Implicit congestion management: A method of informing the terminal that the network is busy. This method relies on the
end-system protocol to detect and fix the congestion problem. (TCP/IP is an example of a protocol using only implicit
congestion management.) See also “explicit congestion management”.

In-band: Refers to the type of signalling over the conversion path on an ISDN call. Contrast “out-of-band”.
Insufficient Ones: A T1 error condition that is logged when fewer than one 1 in 16 0s or less than 12.5 % average 1s

density is received.
Inter Exchange Carrier (IEC): The long distance company (LE) who’s central office provides the point of reference for T1

access. Any common carrier authorized by the FCC to carry customer transmissions between LATAs.
Internet: Refers to the computer network of many millions of university, government and private users around the world.

Each user has a unique Internet Address.
Internet Address (IP Address): A unique 32-bit address for a specific TCP/IP host on a network. Normally printed in dotted

decimal format (e.g., 129.128.44.227).
Internet Protocol (IP): A protocol used to route data from its source to its destination in an Internet enviroment. The

Internet Protocol was designed to connect local area networks. Although there are many protocols that do this, IP refers to
the global system of interconnecting computers. It is a highly distributed protocol (each machine only worries about sending
data to the next step in the route).

Internetwork Packet Exchange (IPX): A NetWare communications protocol used to route messages from one node to
another. IPX packets include network addresses and can be routed from one network to another. An IPX packet can
occasionally get lost when crossing networks, thus IPX does not guarantee delivery of a complete message. Either the
application has to provide that control, or NetWare’s SPX protocol must be used.

Interoperable: Devices from different vendors that can exchange information using a standard’s base protocol.
I/O Addresses: Locations within the I/O address space of your computer used by a device, such as an expansion card, a

serial port, or an internal modem. The address is used for communication between software and a device.
IRQ Level (Interrupt Request Level): The notification a processor receives when another portion of the computer’s

hardware requires its attention. IRQs are numbered so that the device issuing the IRQ can be identified, and so IRQs can
be prioritized.

ISA (Industry Standards Architecture) (pronounced “ice a”): The classic 8 or 16-bit architecture introduced with IBM’s
PC-AT computer.

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ISDN (Integrated Services Digital Network): An International telecommunications standard for transmitting voice, video

and data over a digital communications line. ISDN is a world-wide telecommunications service that uses digital transmission
and switching technology to support voice and digital data communications. Frame relay was partially based on ISDN’s data
link layer protocol (LAPD). Frame relay can be used to transmit across ISDN services offering circuit-switched connection at
64K bps and higher speeds. Contrast Public Switched Telephone Network (PSTN).

ITU-TSS (formerly CCITT): International Telecommunications Union-Telecommunications Sector; the United Nations
organization that prepares standards (“Recommendations”) for resolving communications issues and problems.

J

No Entries.

K

Key Telephone System (KTS): Phone devices with multiple buttons that let you select incoming or outgoing CO phone

lines directly. Similar in operation to a PBX, except with a KTS you don’t have to dial a “9” for a call outside the building.

Key Service Unit (KSU): A small device containing the switching electronics for a business key telephone system (KTS).
Key Set: A telephone set with several buttons for call holding, line pickup, intercom, autodialing, etc. Also called a

touchtone phone (Ericsson) and a KTS (Key Telephone Set).

L

LAPB: Link Access Procedure Balanced; based on the X.25 Layer 2 specification. A full-duplex, point-to-point, bit-

synchronous protocol commonly used as a data link control protocol to interface X.25 DTEs. LAPB is the link initialization
procedure that establishes and maintains communications between the DTE and the DCE.

LAPD: Link Access Protocol for the D-Channel; based on the ISDN Q.921 specification. A full-duplex point-to-point bit­synchronous link-level protocol for ISDN connections; different from LAPB in its framing sequence. Transmission is in units
called “frames”, and a frame may contain one or more X.25 packets.

Line Coding: The representation of 1s and 0s on a T1 line. The two methods of line coding commonly used, B8ZS and
AMI, differ in the restrictions placed on user data. T1 line coding ensures that sufficient timing information is sent with the
digital signal to ensure recovery of all the bits at the far end. Timing information on the T1 line is included in the form of 1s
in the data stream; a long string of 0s in the data stream could cause problems recovering the data.

Line Termination (LT): The electronics at the ISDN network side of the user/network interface that complements the NT1
at the user side. The LT and the NT1 together provide the high-speed digital line signals required for BRI access.

Listed Directory Number (LDN): The main number assigned by the telco; the number listed in the telephone directory and
also provided by Directory Assistance. Some devices can have more than one LDN, such as ISDN devices that have one
LDN for voice and another LDN for data.

Local Area Network (LAN): 1. A computer network located on a user’s premises within a limited geographical area.
Communication within a local area network is not subject to external regulations; however, communication across the LAN
boundary may be subject to some form of regulation. 2. A LAN does not use store-and-forward techniques. 3. A network in
which a set of devices are connected to one another for a communication and that can be connected to a larger network.

Local Access and Transport Area (LATA): A post-divestiture geographical area generally equivalent to a Standard
Metropolitan Statistical Area. At divestiture, the territory served by the Bell system was divided into approximately 161
LATAs. The Bell Operating Companies (BOCs) provide Intra-LATA services.

Local Exchange Carrier (LEC): The local phone company which provides local (i.e., not long distance) transmission
services. AKA “telco”. LECs provide T1 or FT1 access to LDCs (unless the T1 circuit is completely intra-LATA). Inter-LATA
T1 circuits are made up of a combination of Access and Long Haul facilities.

Local Management Interface (LMI): A specification for frame relay equipment that defines status information exchange.
Local Loop: A transmission path, typically twisted-pair wire, between an individual subscriber and the nearest public

telecommunications network switching center. The wires provide ISDN service, but require an NT1 at the user end and an
LT at the network end. (AKA, “loop” or “subscriber loop”.)

Logical Link Control (LLC2): In a local area network, the protocol that governs the exchange of transmission frames
between data stations independently of how the transmission medium is shared. The LLC2 protocol was developed by the
IEEE 802 commitee and is common to all LAN standards.

Logical Unit (LU): A type of network accessible unit that enables end users to gain access to network resources and
communicate with each other.

Long Haul: The T1 element that connects to the Access portion of the long distance company’s (LDC’s) central office. The
LDC is commonly called the point of presence (POP). Each LDC has a number of POPs, located throughout the country.
The LDC is also called an IEC (Inter Exchange Carrier).

Long Haul Communications: The type of phone call reaching outside of a local exchange (LE).

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M

Management Information Base (MIB): A database of network management information used by the Common

Management Information Protocol (CMIP) and the Simple Network Management Protocol (SNMP).
Megacom: An AT&T service with a normal WATS line (typically T1) between the customer premise and the AT&T serving

class 4 CO are the customer’s responibility.

MegaLink: BellSouth’s leased T1 service.
Message: Associated with such terms as packet, frame, and segment. 1. In information theory, an ordered series of

characters intended to convey information. 2. An assembly of characters and sometimes control codes that is transferred as
an entry from an originator to one or more recipients.

Modem: A communications device that enables a computer to transmit information over a telephone line. It converts the
computer’s digital signals into analog signals to send over a telephone line and converts them back to digital signals at the
receiving end. Modems can be internal and fit into an expansion slot, or external and connect to a serial port.

Multiplexer (Mux): 1. A device that takes several input signals and combines them into a single output signal in such a
manner that each of the input signals can be recovered. 2. A device capable of interleaving the events of two or more
activities or capable of distributing the events of an interleaved sequence to the respective activities. 3. Putting multiple
signals on a single channel.

Multiprotocol: A device that can interoperate with devices utilizing different network protocols.
Multithreading: The ability of a software system to be able to handle more than one transaction concurrently. This is

contrasted to the case where a single transaction is accepted and completely processed befor the next transaction
processing is started.

N

Nailed Connection: A permanent or dedicated circuit of a previously switched circuit or circuits.
Nailed-up Circuit: A semi-permanent circuit established through a circuit-switching facility for point-to-point connectivity.
NAK (Negative Acknowledgment): Communications code used to indicate that a message was not properly received, or

that a terminal does not wish to transmit. Contrast with ACK.
Network: A group of computers connected by cables or other means and using software that enables them to share

equipment, such as printers and disk drives to exchange information.

Node: Any point within a network which has been assigned an address.

O

Object-Oriented: A method for structuring programs as hierarchically organized classes describing the data and operations

of objects that may interact with other objects.
Office Channel Unit - Data Port (OCU-DP): The CO channel bank used as the interface between the customer’s DSU and

the channel bank.
Off-hook: The condition of a device which has accessed a phone line (with or without using the line). In modem use, this is

equivalent to a telephone handset being picked up. Dialing and transmission are allowed, but incoming calls are not
answered. Contrast “on-hook”.

Off Premise Extension (OPX): An extension or phone that terminates in a location other than that of the PBX. Commonly
used to provide a corporate member with an extension of the PBX at home.

Ones Density: the measure of the number of logical 1s on a T1 line compared to a given total number of bits on that line;
used for timing information in data recovery in AMI and B8ZS.

On-Hook: The condition of a device which has not accessed a phone line. In modem use, this is equivalent to a telephone
handset that has not been picked up. In other words, it can receive an incoming call. Contrast “off-hook”.

Open Shortest Path First (OSPF): A hierarchical Interior Gateway Protocol (IGP) routing algorithm for IP that is a
proposed standard for the Internet. OSPF incorporates least-cost routing, equal-cost routing, and load balancing.

Outage: The measure of the time during which a circuit is not available for use due to service interrupt. Outage is the
complement of circuit “availability” (100% minus % available = % outage).

Out-of-band: Signaling that is separated from the channel carrying the information (e.g., the voice/data/video signal is
separate from the carrier signal). Dialing and various other “supervisory” signals are included in the signaling element.
Contrast “In-band” signaling.

Out of Frame (OOF): A T1 alarm condition that is logged on the loss of 2, 3 or 4 of 5 consecutive FT framing bits.

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P

Packet: 1. In data communication, a sequence of binary digits, including data and control signals, that is transmitted and

switched as a composite whole. The data, control signals and, possibly, error control information are arranged in a specific
format. 2. Synonymous with data frame. 3. In TCP/IP, the unit of data passed across the interface between the Internet
layer and the link layer. A packet includes an IP header and data. A packet can be a complete IP datagram or a fragment of
an IP diagram. 4. In X.25, a data transmission information unit. A group of data and control characters, transferred as a unit,
determined by the process of transmission. Commonly used data field lengths in packets are 128 or 256 bytes. 5. The field
structure and format defined in the CCITT X.25 recommendation.

Packet Assembler/Dissembler (PAD): Used by devices to communicate over X.25 networks by building or stripping X.25
information on or from a packet.

Packet Data: The information format (“packetized”) used for packet-mode calls.
Packet Mode: Refers to the switching of chunks of information for different users using statistical multiplexing to send them

over the same transmission facility.

Parity bit: An extra bit attached to each byte of synchronous data used to detect errors in transmission.
Permanent Virtual Circuit (PVC): A connection between two endpoints dedicated to a single user. In ISDN, PVCs are

establised by network administration and are held for as long as the user subscribes to the service.
Physical Unit (PU): The component that manages and monitors the resources (such as attached links and adjacent link

stations) associated with a node, as requested by an SSCP via an SSCP-PU session. An SSCP activates a session with the
physical unit in order to indirectly manage, through the PU, resources of the node such as attached links. This term applies
to type 2.0, type 4, and type 5 nodes only.

Point of Presence (POP): The central office’s end points of the long distance carriers.
Point-to-Point Protocol (PPP): A protocol that lets a PC user access TCP/IP (Internet memeber) using an ISDN terminal

adapter or a high-speed modem over a standard telephone line.

Port: A location for input or output data exchange. Computers, muxes, etc. have ports for various purposes.
Primary Rate Interface (PRI): Used on ISDN. In North America, and Japan, PRI is one 64Kbps D channel and 23 B

channels. Elsewhere, it is one D channel and 30 B channels.
Primitive: An abstract representation of interaction across the access points indicating that information is being passed

between the service user and the service provider. The OSI Reference Model defines four types of primitives: Request,
Indication, Response and Confirm.

Private Branch Exchange (PBX): A telephone exchange located on the customer’s premises. The PBX provides a circuit
switching facility for telephone extension lines within the building, and access to the public telephone network. See also
“Exchange”.

PROM (Programmable Read Only Memory - pronounced “prom”): A permanent memory chip that can be programmed
or filled by the customer after by the manufacturer has set initial values. Contrast with ROM.

Protocol: 1. A set of semantic and syntactic rules that determines the behavior of functional units in achieving
communication. 2. In Open Systems Interconnection architecture, a set of semantic and syntactic rules that determine the
behavior of entities in the same layer in performing communication functions. 3. In SNA, the meanings of and the
sequencing rules for requests and responses used for managing the network, transferring data, and synchronizing the
states of network components. 4. Synonomous with line control discipline.

Proxy Server: A secure gateway that provides multiple LAN users with high performance Internet access by functioning as
a TCP/IP proxy server that resides on the outer edge of a firewall.

PSTN (Public Switched Telephone Network): A worldwide public voice telephone network that is used as a
telecommunications medium for the transmission of voice, data and other information.

Public Data Network (PDN): A packet-switched network that is available to the public for individual (“subscriber”) use.
Typically, controlled by a government or a national monopoly.

Public Switched Telephone Network (PSTN): The group of circuit-switching voice carriers, which are commonly used as
analog data communications services.

Pulse Code Modulation (PCM): 1. In data communication, variation of a digital signal to represent information; for
example, by means of pulse amplitude modulation (PAM), pulse duration modulation (PDM), or pulse position modulation
(PPM). 2. Transmissions of analog information in digital form through sampling and encoding the samples with a fixed
number of bits.

Pulse dialing: One of two methods of dialing a telephone, usually associated with rotary-dial phones. Compare with “tone
dialing”.

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Q

Quantizing: The process of analog-to-digital conversion by assigning a range, from the contiguous analog values, to a

discrete number.

R

Random Access Memory (RAM): A computer’s primary workspace. All data must be stored in RAM (even for a short

while), before software can use the processor to manipulate the data. Before a PC can do anything useful it must move
programs from disk to RAM. When you turn it off, all information in RAM is lost.

Rate Enforcement: The concept in frame relay where frames sent faster than the CIR are to be carried only if the
bandwidth is available, otherwise they are to be discarded. (The frame relay network assumes that anything exceeding the
CIR is of low priority.) Rate enforcement makes sure that the network will not get so congested that it isn’t able to meet the
agreed on CIR.

Recognized Private Operating Agency (RPOA): A corporation, private or government-controlled, that provides
telecommunications services. RPOAs, such as AT&T, participate as non-voting members in the CCITT.

Red Alarm: A T1 error condition generated when a local failure (e.g., loss of synchronization) exists for 2.5 seconds,
causing a Carrier Group Alarm (CGA). See also “Blue Alarm” and “Yellow Alarm”.

Request for Comment (RFC): A set of papers in which Internet standards (published and proposed), along with generally­accepted ideas, proposals, research results, etc. are published.

Ring Down Box: A device that emulates a CO by generating POTS calls for testing and product demos.
Ring Down Circuit: A tie line connecting phones where picking up one phone automatically rings another phone. A feature

used for emergencies to alert the person at the other phone of the incoming call.
RJ-11: An industry standard interface used for connecting a telephone to a modular wall outlet; comes in 4-and 6-wire

packages.

RJ-45: An 8-wire modular connector for voice and data circuits.
Robbed Bit Signaling: The popular T1 signaling mechanism where the A and B bits are sent by each side of the T1

termination and are “buried” in the voice data of each voice channel in the T1 circuit. Since the bits are “robbed”
infrequently, voice quality remains relatively uncompromised. See “bit robbing”. The robbed-bit signaling technique is used
in D4 channel banks to convey signaling information. The eighth (least significant) bit of each of the 24 8-bit time slots is
“robbed” every sixth frame to convey voice-related signaling information such as on-hook, off-hook, etc, for each channel.

Router: A device that connects two networks using the same networking protocol. It operates at the Network Layer (Layer

3) of the OSI model for forwarding decisions.
Routing Information Protocol (RIP): A distance vector-based protocol that provides a measure of distance, or hops, from

a transmitting workstation to a receiving workstation.
RS232-C: An EIA standard for a serial interface between computers and peripheral devices (modem, mouse, etc.). It uses a

25-pin DB-25, or a 9-pin DB-9 connector. The RS-232 standard defines the purposes, electrical characteristics and timing of
the signals for each of the 25 lines.

RS-422: The EIA standard for a balanced interface with no accompanying physical connector. RS-422 products can use
screw terminals, DB9, various DB25, and DB37 connectors.

RS-530: The EIA standard for the mechanical/electrical interface between DCEs and DTEs transmitting synchronous or
asynchronous serial binary data. RS-530 provides for high data rates with the same connector used for RS-232; however, it
is incompatible with RS-232.

S

Serial Port: The connector on a PC used to attach serial devices (those that need to receive data one bit after another),

such as a mouse, a printer or a modem. This consists of a 9- or 25-pin connector that sends data in sequence (bit by bit).
Serial ports are referred to as “COMx” ports, where x is 1 to 4 (i.e., COM1 through COM4). A serial port contains a
conversion chip called a “UART” which translates between internal parallel and external serial formats.

Service: The requirements offered by an RPOA to its customers to satisfy specific telecommunications needs.
Severely Errored Seconds (SES): Refers to a typical T1 error event where an error burst occurs (a short term, high bit-

error rate that is self-clearing). Per the ITU-T (CCITT) G.821: any second in which the BER is less than 1x10 -3 .
Signaling: The process of establishing, maintaining, accounting for, and terminating a connection between two endpoints

(e.g., the user premises and the telco CO). Central office signals to the user premises can include ringing, dial tone, speech
signals, etc. Signals from the user’s telephone can include off-hook, dialing, speech to far-end party, and on-hook signals.
In-band signaling techniques include pulse and tone dialing. With common channel signaling, information is carried out-of­band.

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Simple Network Management Protocol (SNMP): TCP/IP protocol that allows network management.
Simultaneous Voice Data (SVD): A technology for letting a user send data via a modem, and use a handset to talk to

another user at the same time over the same connection. The alternative, making a second call, can be expensive or even
impossible. The uses for SVD are telecommuting, videoconferencing, distant learning, tech support, etc.

Stop Bit: One of the variables used for timing in asynchronous data transmission. Depending on the devices, each
character may be trailed by 1, 1.5, or 2 stop bits.

Superframe (D4): A T1 transmission fromat that consists of 12 DS1 frames, or 2316 bits. A DS1 frame consists of 193 bit
positions. A frame overhead bit is in the first position, and it is used for frame and signaling phase alignment only.

Subscriber Loop: See “Local loop”.
Switched 56: A circuit-switched (full duplex digital synchronous data transmission) service that lets you dial a number and

transmit data to it at 56K bps. It is a relatively low cost service, widely used in North America for telecommuting,
videoconferencing and high speed data transfers. Many phone companies are (or will be) phasing out Switched 56 in favor
of ISDN service.

Switched Virtual Circuit (SVC): A type of data transmission where the connection is maintained only until the call is
cleared.

Switched Line: In communications, a physical channel established by dynamically connecting one or more discrete
segments. This connection lasts for the duration of the call, after which each segment can be used as part of a different
channel. Contrast with leased line.

Switched Network: A network in which a temporary connection is established from one point via one or more segments.
Synchronous Data Link Control (SDLC): A discipline conforming to subsets of the Advanced Data Communications

Control Procedures (ADCCP) of the American National Standards Institute (ANSI) and High-level Data Link Control (HDLC)
of the International Organization for Standardization, for managing synchronous, code-transparent, serial-by-bit information
transfer over a link connection. Transmission exchanges may be duplex, or half-duplex over switched or nonswitched links.
The configuration of the link connection may be point-to-point, multipoint, or loop.

Synchronous Transmission: The transmission of data which involves sending a group of characters in a packet. This is a
common method of transmission between computers on a network or between modems. One or more synchronous
characters are transmitted to confirm clocking before each packet of data is transmitted. Compare to Asynchronous
Transmission.

Systems Network Architecture (SNA): The description of the logical structure, formats, protocols, and operational
sequences for transmitting information units through, and controlling the configuration and operation of networks.

T

Tariff: The rate/availability schedule for telephone and ISDN services from a regulated service provider.
TCP/IP: A set of communication protocols that support peer-to-peer connectivity functions for both local and wide area

networks.
T Carrier: The generic name for a digitally multiplexed carrier system. In the North American digital hierarchy, a T is used to

designate a DS (digital signal) level hierarchy. Examples: T1 (DS1) is a 1.544 M bps 24-channel designation. In Europe, T1
is called E1. The T Carrier system was originally designed for transmitting digitized voice signals, but has since been
adapted for digital data applications.

T1: A digital transmission link capable of 1.544M bps. T1 uses two pairs of normal UTP, and can handle 24 voice
conversations, each digitized at 64K bps. T1 is a standard for digital transmission in the U.S., Canada, Japan and Hong
Kong. T1 is the access method for high-speed services such as ATM, frame relay, and SMDS. See also T Carrier, T1 line
and FT1.

T1 Channel Tests: A set of diagnostics that vary by carrier, used to verify a T1 channel operation. Can include Tone, Noise
Level, Impulse Noise Level, Echo Cancelers, Gain, and Crosstalk testing.

T1 Framing: To digitize and encode analog voice signals requires 8000 samples per second (twice the highest voice
frequency of 4000 Hz). Encoding in an 8-bit word provides the basic T1 block of 64K bps for voice transmission. This “Level
0 Signal, as its called, is represented by “DS-0”, or Digital Signal at Level 0. 24 of these voice channels are combined into a
serial bit stream (using TDM), on a frame-by-frame basis. A frame is a sample of all 24 channels; so adding in a framing bit
gives a block of 193 bits (24x8+1=193). Frames are transmitted at 8000 per second (the required sample rate), creating a

1.544M (8000x193=1.544M) transmission rate.
T1 Line: A digital communications facility that functions as a 24-channel pathway for data or voice transmission. A T1 line is

composed of two separate elements: the Access element and the Long Haul element.
T1 Mux: A device used to carry many sources of data on a T1 line. The T1 mux assigns each data source to distinct DS0

time slots within the T1 signal. Wide bandwidth signals take more than one time slot. Normal voice traffic or 56/64K bps
data channels take one time slot. The T1 mux may use an internal or external T1 DSU; a “channel bank” device typically
uses an external T1 CSU.

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Transmission Control Protocol / Internet Program (TCP/IP): A multi-layer set of protocols developed by the US

Department of Defense to link dissimilar computers across dissimilar and unreliable LANs.
Terminal: The screen and keyboard device used in a mainframe environment for interactive data entry. Terminals have no

“box”, which is to say they have no file storage or processing capabilities.
Terminal Adapter (T A): An ISDN DTE device for connecting a non-ISDN terminal device to the ISDN network. Similar to a

protocol converter or an interface converter, a TA connects a non-ISDN device between the R and S interfaces. Typically a
PC card.

Tie line: A dedicated circuit linking two points without having to dial a phone number (i.e., the line may be accessed by
lifting the telephone handset or by pushing a button).

Time-Division Multiplexing (TDM): Division of a transmission facility into two or more channels by allotting the common
channel to several different information channels, one at a time.

Time Slot: One of 24 channels within a T1 line. Each channel has a 64K bps maximum bandwidth. “Time slot” implies the
time division multiplexing organization of the T1 signal.

Toll Call: A call to a location outside of your local service area (i.e., a long distance call).
Tone dialing: One of two methods of dialing a telephone, usually associated with Touch-Tone® (push button) phones.

Compare with pulse dialing.
Topology: Physical layout of network components (cables, stations, gateways, and hubs). Three basic interconnection

topologies are star, ring, and bus networks.
Transmission Control Protocol (TCP): A communications protocol used in Internet and in any network that follows the US

Department of Defense standards for internetwork protocol. TCP provides a reliable host-to-host protocol between hosts in
packet-switched communications networks and in interconnected systems of such networks. It assumes that the Internet
protocol is the underlying protocol.

Transport Layer: Layer 4 of the Open Systems Interconnection (OSI) model; provides reliable, end-to-end delivery of data,
and detects transmission sequential errors.

Transport Protocol Data Unit (TPDU): A transport header, which is added to every message, contains destination and
source addressing information that allows the end-to-end routing of messages in multi-layer NAC networks of high
complexity. They are automatically added to messages as they enter the network and can be stripped off before being
passed to the host or another device that does not support TPDU’s.

Trunk: Transmission links that interconnect switching offices.
TSR (terminate and stay resident): A software program that remains active and in memory after its user interface is

closed. Similar to a daemon in UNIX environments.

Tunneling: Encapsulation data in an IP packet for transport across the Internet.
Twisted pair wiring: A type of cabling with one or more pairs of insulated wires wrapped around each other. An inexpensive

wiring method used for LAN and telephone applications, also called UTP wiring.

U

UART (Universal Asynchronous Receiver/Transmitter) (pronounced “you art”): A chip that transmits and receives data

on the serial port. It converts bytes into serial bits for transmission, and vice versa, and generates and strips the start and
stop bits appended to each character.

UNIX: An operating system developed by Bell Laboratories that features multiprogramming in a muti-user environment.
Unshielded Twisted Pair (UTP): Telephone-type wiring. Tansmission media for 10Base-T.

V

V.25bis: An ITU-T standard for synchronous communications between a mainframe or host and a modem using HDLC or

other character-oriented protocol.
V.54: The ITU-T standard for local and remote loopback tests in modems, DCEs and DTEs. The four basic tests are:

• local digital loopback (tests DTE send and receive circuits),

• local analog loopback (tests local modem operation),

• remote analog loopback (tests comm link to the remote modem), and

• remote digital loopback (tests remote modem operation).

Virtual Circuit: A logical connection. Used in packet switching wherin a logical connection is established between two
devices at the start of transmission. All information packets follow the same route and arrive in sequence (but do not
necessarily carry a complete address).

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W

Wide Area Network (WAN): 1. A network that provides communication services to a geographic area larger than that

served by a local area network or a metropolitan area network, and that may use or provide public communication facilities.

2. A data communications network designed to serve an area of hundreds or thousands of miles; for example, public and
private packet-switching networks, and national telephone networks. Contrast with local area network (LAN).

Wide Area Telecommunications Service (WATS): A low-cost toll service offered by most long distance and local phone
companies. Incoming (800 call service, or IN-WATS) and outgoing WATS are subscribed to separately, but over the same
line.

X

X.25: ITU-T’s definition of a three-level packet-switching protocol to be used between packet-mode DTEs and network

DCEs. X.25 corresponds with layer 3 of the 7-layer OSI model.

Y

Yellow Alarm: An error indication sent by the T1 device when it has not gotten a receive signal, or cannot synchronize on

the receive signal received. Contrast “Red Alarm” and “Blue Alarm”.

Z

Zero Byte Time Slot Interchange (ZBTSI): A method for allowing 64K bps unrestricted user data (allowing all 0s in the

user data). An alternative to (but not as popular as) B8ZS.

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