Patton electronics 2701/I User Manual

USER
MANUAL

MODEL 2701/I

G.703/G.704 NTU with
10Base-T Ethernet Interface

SALES OFFICE
[phone]
TECHNICAL SUPPORT
[phone]
http://www.patton.com

An ISO-9001

Certified Company

Part# 07M2701/I-D
Doc# 086091UD
Revised 11/20/00

1.0 WARRANTY INFORMATION

Patton Electronics warrants all Model 2701/I components to be
free from defects, and will—at our option—repair or replace the prod­uct should it fail within one year from the first date of shipment.

This warranty is limited to defects in workmanship or materials,
and does not cover customer damage, abuse, or unauthorized modifi­cation. If this product fails or does not perform as warranted, your sole
recourse shall be repair or replacement as described above. Under no
condition shall Patton Electronics be liable for any damages incurred
by the use of this product. These damages include, but are not limited
to, the following: lost profits, lost savings and incidental or consequen­tial damages arising from the use of or inability to use this product.
Patton Electronics specifically disclaims all other warranties,
expressed or implied, and the installation or use of this product shall
be deemed an acceptance of these terms by the user.

1.1 RADIO AND TV INTERFERENCE

The Model 2701/I generates and uses radio frequency energy, and
if not installed and used properly—that is, in strict accordance with the
manufacturer's instructions—may cause interference to radio and tele­vision reception. The Model 2701/I has been tested and found to com­ply with the limits for a Class A computing device in accordance with
the specifications in Subpart J of Part 15 of FCC rules, which are
designed to provide reasonable protection from such interference in a
commercial installation. However, there is no guarantee that interfer­ence will not occur in a particular installation. If the Model 2701/I does
cause interference to radio or television reception, which can be deter­mined by disconnecting the cables, the user is encouraged to try to
correct the interference by one or more of the following measures:
moving the computing equipment away from the receiver, re-orienting
the receiving antenna, and/or plugging the receiving equipment into a
different AC outlet (such that the computing equipment and receiver
are on different branches).

1.2 CE NOTICE

The CE symbol on your Patton Electronics equipment indicates
that it is in compliance with the Electromagnetic Compatibility (EMC)
directive and the Low Voltage Directive (LVD) of the Union European
(EU). A Certificate of Compliance is available by contacting Technical
Support.

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1.3 SERVICE

All warranty and nonwarranty repairs must be returned freight pre­paid and insured to Patton Electronics. All returns must have a Return
Materials Authorization number on the outside of the shipping contain­er. This number may be obtained from Patton Electronics Technical
Support at:

tel: [phone];

email: [e-mail]; or,

www: http://www.patton.com.

Patton Electronics' technical staff is also available to answer any
questions that might arise concerning the installation or use of your
Patton Model 2701/I. Technical Support hours: 8AM to 5PM EST,

Monday through Friday.

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WARNING!

This device is not intended to be con-

nected to the public telephone network.

NOTE: Packages received without an RMA number will not

be accepted.

2.0 GENERAL INFORMATION

Thank you for your purchase of this Patton Electronics product.
This product has been thoroughly inspected and tested and is warrant­ed for One Year parts and labor. If any questions or problems arise
during installation or use of this product, please do not hesitate to con­tact Patton Electronics Technical Support at [phone].

2.1 FEATURES

• Terminates G.703 and G.704, E1/fractional E1 service

• Available in low-cost standalone or rack-mountable versions

• n x 64 kbps data rates to 2.048 Mbps

• 10Base-T Ethernet bridge

• PPP (Point to Point Protocol, RFC 1661) with Bridge Control
Protocol (RFC 1638)

• 75-ohm dual coax and 120-ohm twisted-pair G.703 connections

• Local and remote loopback diagnostics

• Internal and G.703 network timing

• CE and BABT approvals

• 90-260VAC & 48VDC power options

• Conforms to ONP requirements CTR 12 and CTR 13 for connec­tion to international Telecom networks

2.2 DESCRIPTION

The Model 2701/I receives channelized G.704 (n x 64kbps) or

clear channel E1/G.703 (2.048-Mbps) data from the telco's digital data
network. The Model 2701/I terminates the G.703 telco interface and
converts the data for transmission to a user-oriented 10Base-T (802.3)
Ethernet interface.

The Model 2701/I supports an integrated 10Base-T (802.3)

Ethernet port with transparent bridging capability for IP, IPX, DECnet,
NetBIOS and other layer-3 protocols. The 2701/I attaches to the LAN
and intelligently bridges data traffic to the large central site router
through the telco's leased line network. The 2701/I supports PPP (RFC

1661) and BCP (RFC 1638).
The Model 2701/I is a 10Base-T bridge that operates over

G.703/G.704 lines. It uses MAC learning and forwarding to provide
seamless LAN-to-LAN connectivity. As a result, corporate enterprises
can connect their servers to a pair of NTUs and automatically forward
data packets that are meant for the remote network. Local packets are
filtered and passed only to the local LAN.

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3.0 PPP Operational Background

PPP is a protocol used for multi-plexed transport over a point­to-point link. PPP operates on all full duplex media, and is a sym­metric peer-to-peer protocol, which can be broken into three main
components: 1. A standard method to encapsulate datagrams
over serial links; 2. A Link Control Protocol (LCP) to establish, con­figure, and test the data-link connection; 3. A family of Network
Control Protocols (NCPs) to establish and configure different net­work layer protocols.

In order to establish communications over a point-to-point link,
each end of the PPP link must first announce its capabilities and
agree on the parameters of the link’s operation. This exchange is
facilitated through LCP Configure-Request packets.

Once the link has been established and optional facilities have
been negotiated, PPP will attempt to establish a network protocol.
PPP will use Network Control Protocol (NCP) to choose and con­figure one or more network layer protocols. Once each of the net­work layer protocols have been configured, datagrams from the
established network layer protocol can be sent over the link. The
link will remain configured for these communications until explicit
LCP or NCP packets close the link down, or until some external
event occurs.

The PPP Bridging Control Protocol (BCP), defined in RFC
1638, configures and enables/disables the bridge protocol on
both ends of the point-to-point link. BCP uses the same
packet exchange mechanism as the Link Control Protocol
(LCP). BCP is a Network Control Protocol of PPP, bridge
packets may not be exchanged until PPP has reached the
network layer protocol phase.

3.1 APPLICATIONS

In situations where a routed network requires connectivity
to a remote Ethernet network, the interface on a router can
be configured as a PPP IP Half Bridge. The serial line to the
remote bridge functions as a Virtual Ethernet interface, effec­tively extending the routers serial port connection to the
remote network. The bridge device sends bridge packets
(BPDU's) to the router's serial interface. The router will
receive the layer three address information and will forward
these packets based on its IP address.

Figure 1 shows a typical Cisco router with a serial interface
configured as a PPP Half Bridge. The router serial interface uses
a remote device that supports PPP bridging to function as a node
on the remote Ethernet network. The serial interface on the
Cisco will have an IP address on the same Ethernet subnet as
the bridge.

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4.0 CONFIGURATION

The Model 2701/I features configuration capability via hardware
DIP switches. This section describes all possible DIP switch configura­tions of the Model 2701/I.

4.1 DIP SWITCH CONFIGURATION

The Model 2701/I has two sets of internal DIP switches that allow
configuration for a wide range of applications. The sets of switches are
accessed from the underside. Figure 3 (below) shows the location of
the DIP switches on the bottom of the printed circuit board.

The Model 2701/I DIP switches (Switch Sets 1-2) can be config­ured as either “ON” or “OFF”. Figure 4 (below) shows the orientation
of the DIP switches with respect to ON/OFF positions.

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Figure 3. Underside of Model 2701/I, Showing Location of DIP Switches

Front

Rear

ON

S1

S2

OFF

Figure 4. Close up of configuration switches

OFF

ON

ON

For example, the customer site is assigned the addresses

192.168.1.0/24 through 192.168.1.1/24. The address

192.168.1.1/24 is also the default gateway for the remote net­work. The above settings remove any routing/forwarding intel­ligence from the CPE. The associated Cisco configuration will
set serial interface (s0) to accommodate half bridging for the
above example.

Authentication is optional under PPP. In a point-to-point
leased-line link, incoming customer facilities are usually fixed
in nature, therefore authentication is generally not required. If
the foreign device requires authentication via PAP or CHAP,
the PPP software will respond with default Peer-ID consisting
of the units Ethernet MAC address and a password which
consists of the unit’s Ethernet MAC address.

Some networking systems do not define network numbers
in packets sent out over a network. If a packet does not have
a specific destination network number, a router will assume
that the packet is set up for the local segment and will not for­ward it to any other sub-network. However, in cases where
two devices need to communicate over the wide-area, bridg­ing can be used to transport non-routable protocols.

Figure 2 illustrates transparent bridging between two
routers over a serial interface (s0). Bridging will occur
between the two Ethernet Interfaces on Router A (e0 and e1)
and the two Ethernet Interfaces on Router B (e0 and e1).

Patton
2701/I
Bridge

Ethernet LAN

PEC Device w/ Serial I/F

Router

Figure 1. Cisco router with serial interface, configured as PPP Half Bridge.

!
no ip routing
!
interface Ethernet0
ip address 1.1.1.1 255.255.255.0
bridge-group 1
!
interface Serial0
ip address 1.1.1.1 255.255.255.0
encapsulation PPP
bridge-group 1
!
interface Serial1
ip address 2.2.2.2 255.255.255.0
bridge-group 1
!
bridge 1 protocol ieee
!

Router A

Router B

e0

e0

S1

e1

S1

S0

S0

LAN

LAN

LAN

LAN

LAN

Serial Interface

Serial Interface

Using Bridge-Groups, multi­ple remote LANs can be
bridged over the wide-area.

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2701/I

2701/I

E1/FE1 Link

E1/FE1 Link

Figure 2. Transparent bridging between two routers over a serial interface.