3COM LINKBUILDER MSH 4 PORT ETHERNET BRIDGE MODULE, DUA1860-0AAA01 User Manual

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HE LINKBUILDER

MSH

4 P

ODULE

SER

ORT

THERNET

UIDE

RIDGE

Part No. DUA1860-0AAA01 Published November 1994

3Com Corporation ■ 5400 Bayfront Plaza ■ Santa Clara, California ■ 95052-8154

© 3Com Corporation, 1994. All rights reserved. No part of this documentation may be reproduced in any form or by any means or used to make any derivative work (such as translation, transformation, or adaptation) without permission from 3Com Corporation.

3Com Corporation reserves the right to revise this documentation and to make changes in content from time to time without obligation on the part of 3Com Corporation to provide notification of such revision or change.

3Com Corporation provides this documentation without warranty of any kind, either implied or expressed, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. 3Com may make improvements or changes in the product(s) and/or the program(s) described in this documentation at any time.

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If you are a United States government agency, then this documentation and the software described herein are provided to you subject to the following restricted rights:

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Restricted Rights Legend: Use, duplication or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) (1) (ii) for restricted Rights in Technical Data and Computer Software clause at 48 C.F.R. 52.227-7013. 3Com Corporation, 5400 Bayfront Plaza, Santa Clara, California 95052-8145.

For civilian agencies:

Restricted Rights Legend:

subparagraph (a) through (d) of the Commercial Computer Software - Restricted Rights Clause at 48 C.F.R. 52.227-19 and the limitations set forth in 3Com’s standard commercial agreement for the software. Unpublished rights reserved under the copyright laws of the United States.

3Com and LinkBuilder are registered trademarks of 3Com Corporation. Registered trademarks are registered in the United States, and may or may not be registered in other countries.

3ComFacts, Ask3Com, CardFacts, NetFacts, and CardBoard are service marks of 3Com Corporation.

CompuServe is a registered trademark of CompuServe, Inc. The technology behind 3Com’s LAN Security Architecture is protected by U.S. patent 5161192 (world

patents pending). Other brand and product names may be registered trademarks or trademarks of their respective

holders. Revision: 01

Use, reproduction or disclosure is subject to restrictions set forth in

ONTENTS

BOUT THIS GUIDE

Introduction ix How To Use This Guide x Conventions xi Special Messages xii Related Publications xiii

NTRODUCTION

The LinkBuilder MSH 1-2 The LinkBuilder MSH 4 Port Ethernet Bridge Module 1-3 Managing The Bridge 1-7 Bridging 1-8

Why Use A Bridge? 1-8 Local And Remote Bridges 1-9 Bridge Network Topology 1-10 Learning, Filtering And Forwarding 1-12 Spanning Tree Algorithm And Protocol (STAP) 1-16

Bridge Filters 1-20

What Is Custom Filtering? 1-20 Filter Sets 1-23

Host-to-Host Filtering 1-23 Host-to-Port Filtering 1-24 Port-to-Port Filtering 1-26 Multicast-to-Port Filtering 1-27 Protocol Filtering 1-27 Bit Filtering 1-28

Enabling Custom Filtering 1-29 Simple Network Management Protocol (SNMP) 1-30 Installation And Removal 1-31

Safety Information 1-31 Anti-Static Information 1-31

ETTING STARTED

Introduction 2-2 The VT100 Management Interface 2-3

The VT100 Bridge Screens 2-4 The VT100 Bridge Menu Map 2-6 Bridge Control Keys 2-8 Simple Bridge Configuration 2-11

Logging On To The LinkBuilder MSH 2-12

Logging On To The Bridge 2-17

Establishing Operator Accounts 2-18

Adding Bridge Information 2-24

Saving And Making Changes Effective 2-26

Erasing All Changes 2-27

Logging Off The Bridge 2-28 IP Address Configuration 2-29

Bridge Connections 2-30

Logging On To The Bridge 2-30 Telnet From The Bridge 2-30

Setting Up Remote Access 2-31

Active 2-32 Next Reset 2-32 Static Routes 2-33

Assigning Host Name / IP Address Pairs 2-36 Us in g P IN G To Tes t C on ne ct io ns 2- 38 Telnet Log On To Another IP Device From The Bridge 2-42

Talking To Another Bridge User 2-44

Telnet Suspension 2-45

Tel ne t L og Off 2- 45

SNMP Configuration 2-46

Community Administration 2-46 Trap s 2- 47 Configuring Basic Community Characteristics 2-48 Configuring Community Traps 2-51

DVANCED BRIDGING

Introduction 3-2 Spanning Tree Configuration 3-2

Spanning Tree Bridge Configuration 3-3 Spanning Tree Port Configuration 3-6

Custom Filter Configuration 3-9

Setting Up A Host-to-Host Filter Set 3-10

Saving Host-to-Host Filters 3-12

Setting Up A Host-to-Port Filter Set 3-13

Saving Host-to-Port Filters 3-15

Setting Up A Port-to-Port Filter Set 3-16

Saving Port-to-Port Filters 3-17

Setting Up A Multicast-to-Port Filter Set 3-18

Saving Multicast-to-Port Filters 3-19

Setting Up A Protocol Filter Set 3-20

Saving Protocol Filters 3-22

Setting Up A Bit Filter 3-23

Saving Bit Filters 3-26

The Host Filtering Table 3-27

Saving Host Filtering Table And Filter Set Changes 3-29

Saving And Turning Filters On And Off 3-30

ONITORING

Introduction 4-2 Checking Bridge Statistics 4-3

Rcvd 4-5 Xmit 4-5 Pkts 4-6

Checking Port Activity 4-8

Rcvd 4-10 Xmit 4-10 Pkts 4-11

Viewing Ethernet Statistics 4-12

Received 4-13 Transmitted 4-14

Checking User Access 4-16

URTHER CONFIGURATION AND MONITORING

General Help 5-2 Configuration 5-3

Downloading Software Upgrades 5-3 The Permanent Database 5-6

Add Permanent Entry 5-6

Delete Permanent Entry 5-8

Transfer Permanent Entries 5-9 Editing ARP Information 5-10

ARP Parameters 5-10

Add ARP Entry 5-11

Delete ARP Entry 5-12 Changing TCP Characteristics 5-13 Changing Telnet Characteristics 5-14 Port Queuing 5-16

Monitoring 5-17

Viewing General Bridge Information 5-17

Viewing Node Table Information 5-19

Node Table By Address 5-19

Node Table By Hash Bucket 5-20 Viewing The Hardware Configuration 5-22 Viewing Socket Statistics 5-23

Viewing UDP Statistics 5-26

Viewing TCP Information 5-28

TCP Data Statistics 5-28

Packets Received 5-28

Packets Sent 5-30

TCP Connection Statistics 5-31 Viewing IP Statistics 5-33

total packets received 5-33

fragments received 5-34 Viewing ICMP Packet Statistics 5-36 Viewing SNMP Information 5-39

SNMP Statistics 5-39

In Packets 5-39

Out Packets 5-40

SNMP Authentication Statistics 5-42 Viewing ARP Tables 5-43 Viewing Diagnostic Information 5-45

Error Log 5-45

Interactive Diags 5-46

Clear Error Log 5-47

ROBLEM SOLVING

Spot Checks 6-2 Using The LEDs For Fault Diagnosis 6-3 Correcting Problems 6-4

Network Problems 6-4 PING Or Telnet Problems 6-4 Port Problems 6-5 Performance Problems 6-5 Collision Problems 6-6 STAP Problems 6-6 Filter Problems 6-6 SNMP Problems 6-7

Operation Problems 6-7 Removing And Replacing Equipment 6-8 Spares 6-9 What To Do Next 6-10

INK SETTINGS

ECHNICAL INFORMATION

Electrical B-1

Safety B-1

EMC B-1

Environmental B-1

Reliability B-1

MIB B-2

ECHNICAL SUPPORT

On-line Technical Services C-1

3Com Bulletin Board Service (3ComBBS) C-1 Ask3Com on CompuServe C-2

3ComFacts Automated Fax Service C-2 3Com Documentation on CD-ROM C-3 Support from Your Network Supplier C-4 Support from 3Com C-4 Returning Products for Repair C-5

NDEX

ADIO FREQUENCY INTERFERENCE STATEMENTS

IMITED WARRANTY

Introduction

This guide contains all the information you need to install and use the LinkBuilder MSH 4 Port Ethernet Bridge Module. It is written for the person responsible for the management and maintenance of the network.

The guide explains:

■ How to configure the 4 Port Bridge Module.

■ How to identify 4 Port Bridge Module problems and possible

solutions to these problems.

The guide does not explain:

■ How to design your network.

■ How to install and use the LinkBuilder MSH chassis, its Power

Supply Units, the Management Module or any other modules. Refer to the guides listed in the Useful Publications section.

BOUT THIS

UIDE

The quick reference guide that also accompanies this guide duplicates some of the information from this guide. As it is intended for reference use, we recommend that it is stored in the holder underneath the LinkBuilder MSH chassis.

Throughout this guide, we assume that you are familiar with the concepts and operation of your Local Area Network. For VT100 and Telnet management, we also assume that you are familiar with the VT100 management interface.

x A

BOUT THIS GUIDE

How To Use This Guide

The following list shows where to find specific information:

If you are looking for: Turn to:

An introduction to the LinkBuilder MSH, the 4 Port Ethernet Bridge Module, bridging and filtering

How to configure a simple bridge Chapter 2 How to configure an advanced bridge Chapter 3 How to perform simple bridge monitoring Chapter 4 Information about further bridge configuration and

monitoring Information about problem solving Chapter 6 Information about link settings Appendix A Technical information Appendix B How to obtain technical support Appendix C

We recommend that you read Chapter 2 when setting up the bridge for the first time, in a new environment. Read Chapter 3 for more advanced bridge configuration, if necessary. Read Chapter 4 when regularly checking the bridge.

Chapter 1

Chapter 5

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Conventions xi

Conventions

The following table lists conventions that are used throughout this guide:

“Enter” vs. “Type” When the word “enter” is used in this guide, it means type

something, then press the [Return] or [Enter] key. Do not press the [Return] or [Enter] key when an instruction simply says “type.”

Text represented as

screen display

Text represented as

user entry

Keys When specific keys are referred to in the text, they are shown

Italics

This typeface

on your terminal screen, for example:

Enter old password:

This typeface

enter, for example:

set pwd

in brackets, for example [Return] or [Esc]. If two or more keys are to be pressed simultaneously, the keys

are linked with a plus sign (+), for example: Press [Ctrl]+[Alt]+[Del]. In text, italics are used to denote

is used to represent displays that appear

is used to represent commands that you

new terms

emphasis

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xii A

BOUT THIS GUIDE

Special Messages

A special format indicates notes, cautions, and warnings. These messages are defined as follows:

Notes call attention to important features or instructions.

CAUTION:

Cautions contain directions that you must follow to

avoid immediate system damage or loss of data.

WARNING:

Warnings contain directions that you must follow for

your personal safety. Follow all instructions carefully.

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Related Publications

If you need more information about subjects not covered by this guide, you may find it useful to refer to the guides that accompany your other LinkBuilder products.

If you have lost or do not have a particular guide, copies can be obtained from your supplier.

The following guides are particularly useful:

How To Install And Use The LinkBuilder MSH/11

(DUA1800-0AAA0x)

The LinkBuilder MSH Management Module

Volume 1 (DUA1850-0AAA0x) Volume 2 (DUA1850-0BAA0x)

Related Publications xiii

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xiv A

BOUT THIS GUIDE

DUA1860-0AAA01

■ The LinkBuilder MSH

■ The LinkBuilder MSH 4 Port Ethernet Bridge Module

■ Managing The Bridge

■ Bridging

■ Bridge Filters

■ Simple Network Management Protocol (SNMP)

■ Installation And Removal

NTRODUCTION

This chapter contains the following topics:

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NTRODUCTION

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The LinkBuilder MSH

The LinkBuilder MSH is an extremely versatile chassis-based hub, which enables you to connect and manage large, mixed-technology, mixed-media LANs.

The basis of the LinkBuilder MSH is the chassis, into which a series of network specific modules can be installed, as shown in Figure

1-1. The modules within the chassis connect to a backplane. It is

the backplane which allows communication between the various LANs and LAN segments connected to the LinkBuilder MSH. Contact your supplier for the latest list of modules available.

Figure 1-1 The LinkBuilder MSH

The LinkBuilder MSH's backplane contains three Ethernet busses. Ethernet modules can connect to any bus or be independent of the chassis; this is the versatility of the LinkBuilder MSH.

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The LinkBuilder MSH 4 Port Ethernet Bridge Module 1-3

The LinkBuilder MSH 4 Port Ethernet Bridge Module

The bridge module provides a bridge connection between the three Ethernet busses of the MSH and an external port (the bridge module's transceiver module), as shown in Figure 1-2 bridge's connections are referred to as ports (1, 2, 3 and E).

1 2 3

. The

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Figure 1-2

The Network Segments

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The bridge module provides:

Connection to each Ethernet bus in the MSH.

■

An external connection by transceiver module.

■

LEDs for indicating bridge activity and diagnosing possible

■

problems. Standard IEEE 802.1 Part D transparent bridging.

■

Additional custom bridge filtering:

■

Host-to-Host filtering

■

Host-to-Port filtering

■

Port-to-Port filtering

■

Multicast-to-Port filtering

■

Protocol filtering

■

Bit filtering

Spanning Tree Algorithm and Protocol (STAP).

■

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The LinkBuilder MSH 4 Port Ethernet Bridge Module 1-5

Below its top ejector, the bridge has a panel of LEDs that indicate bridge activity, as shown in Figure 1-3

Each port has a row of three LEDs; transmit (TX), receive (RX) and enabled (EN). Ports with numbers signify the Ethernet bus in the LinkBuilder MSH chassis to which the port is connected. The unnumbered row is for the external port, the Transceiver Module.

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Figure 1-3

The Module’s LEDs

You can also use the LEDs to help with diagnosing faults on your system, for more information refer to

Diagnosis

on page 6-3.

Using The LEDs For Fault

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A Transceiver Module can be fitted to the bridge, providing its fourth port, as shown in Figure 1-4

. A range of Modular Transceivers are produced by 3Com, allowing you flexibility when deciding on network connections and cabling:

3C12060 Female AUI Transceiver Module

■

3C12065 Fiber Transceiver Module (ST)

■

3C12064 Fan Out Transceiver Module

■

3C12066 Coaxial Transceiver Module

■

3C12060 LinkBuilder Bridge MicroModule

■

Your supplier will know of any other Transceiver Modules not listed here.

Figure 1-4 The Transceiver Module

Instructions on how to fit a Transceiver Module are given in the manual that accompanies it.

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Managing The Bridge

The bridge can be managed using either the VT100 management interface or remotely via SNMP using a suitable application, as shown in Figure 1-5 management facilities.

Managing The Bridge 1-7

. SNMP provides a subset of the VT100

■

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Figure 1-5

VT100 Management

To use the VT100 management interface:

Connect a VT100 terminal or VT100 terminal emulator directly to the serial port on the display panel of the LinkBuilder MSH.

Use a VT100 terminal emulator over a network, via Telnet.

To manage the bridge, you must have a LinkBuilder MSH Management Module (3C18500) with software version 2.1 or later installed. If you do not have a Management Module installed, contact your supplier.

Please refer to

The LinkBuilder MSH Management Module

manuals for information on connecting VT100.

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NTRODUCTION

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Bridging

This section describes bridges and how they work.

Why Use A Bridge?

Bridges provide a way of joining two or more networks together to form a single logical and physical network.

You can overcome various network restrictions that apply to large individual networks by bridging smaller networks together. The bridge remains transparent to the users of these networks.

The original networks that form the bridged network are called

network segments

devices on the network can be reached via each of its ports. It reduces the amount of traffic on each network segment by filtering traffic that does not need to be forwarded to it. Standard filtering is described in

page 1-12.

. The bridge learns, from network traffic, what

Learning, Filtering And Forwarding

You can also apply custom filters to restrict communication through the bridge. This allows you to add some security to your network. Custom filtering is described in

Bridge Filters

on page

1-20.

Resilience can be built into a bridged network. The bridges on the network can control the flow of traffic throughout the network. Resilience is described in

on page 1-16.

(STAP)

Spanning Tree Algorithm And Protocol

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Local And Remote Bridges

Bridging 1-9

There are two main types of bridge,

local

and

remote

. The

LinkBuilder MSH 4 Port Ethernet Bridge Module is a local bridge.

Local bridges are used for bridging networks on the same site, as shown in Figure 1-6

Figure 1-6

Local Bridge

Remote bridges are used for bridging networks across large areas. A remote bridge is often called a

half

bridge because each network connects to half of the remote bridge. The remote bridge halves are connected by a Wide Area Network (WAN) link, as shown in Figure 1-7

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Figure 1-7

Remote Bridge

Both types of bridge have essentially the same operation and functionality.

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Bridge Network Topology

The

topology

of a network is essentially its layout; how its component parts are inter-connected. The topology of your network is dependent on the amount of bridges that you use and the way in which you use them. If you use one 4 Port Ethernet Bridge Module, you may have a

In the example setups shown in Figure 1-8

topology.

star

and Figure 1-9, the bridge connects all three MSH busses and an external segment.

Figure 1-8

physically connected, and Figure 1-9

shows how the devices, modules and MSH chassis are

shows the resulting

topology.

Figure 1-8 An Example Bridge Setup

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Bridging 1-11

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Figure 1-9

An Example Topology

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Learning, Filtering And Forwarding

Transparent

bridges remain transparent to the network segments, treating them as one overall network. The main operations of a transparent bridge are

learning, filtering

and

forwarding

. These operations are 802.1 bridge features and enable it to control the flow of traffic to each network segment.

Devices send information as frames. The two main types of frame are 802.3 and Ethernet. The destination address and source address are contained within the frame, as shown in Figure 1-10

Destination Address

802.3 frame Destination

Address Ethernet frame

Figure 1-10 Frame Contents

Source Address

Length

Type

Data

Frame Checksum

Every time the bridge receives a packet, it looks at the source address and destination address. If the bridge has not previously received a packet on that port from the device, it learns the source address by adding it to a list of device addresses connected to the port. The bridge then compares the destination address to the address lists for all the ports on the bridge. If the destination address appears on the address list of a port that did not receive the packet, the bridge

forwards

(duplicates) the packet to that port. If the destination address appears on the address list of the same port that received the packet, the bridge

filters

(discards) the packet. If the destination address does not appear on any of its address lists, the bridge passes it on to all but the receiving port, called

flooding

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Bridging 1-13

Figure 1-11, Figure 1-12, Figure 1-13 and Figure 1-14 illustrate

how a bridge learns device addresses and uses address lists to reduce unnecessary network traffic.

Figure 1-11

: The bridge does not know what devices are on the

network.

Figure 1-11

An Example Network

Figure 1-12: Device A, connected to port 1, transmits a packet for

device B. The bridge learns the address of device A but does not know where device B is, so it passes the packet to ports 2, 3 and E.

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Figure 1-12

Learns A, Passes On Packet

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Figure 1-13: Device C, connected to port 2, transmits a packet for

device A. The bridge learns the address of device C and recognizes the address of device A, so it forwards the packet to port 1.

Figure 1-13 Learns C, Forwards Packet

Figure 1-14: Device D, connected to port 2, transmits a packet for

device C. The bridge learns the address of device D and recognizes the address of device C is on the same address list, so it filters the packet.

Figure 1-14 Learns D, Filters Packet

The bridge can now effectively control network traffic by forwarding packets only to relevant network segments.

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Bridging 1-15

The bridge performs

ageing

on address list entries. If a port has

not received a packet from a device within a configured time (the

ageing time

), the device's address will be removed from the port's address list. This helps the bridge to efficiently remember devices that communicate frequently without having to cope with devices that communicate infrequently or are no longer there.

Because the bridge continually learns new addresses and ages out old addresses, it does not have to be reconfigured or initialized when a device is added to the network.

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Spanning Tree Algorithm And Protocol (STAP)

You can make your network more resilient by adding bridges and network segments. If a network segment or bridge fails, traffic can still travel through the network by using the additional bridges and network segments.

The key to resilience is the number of paths through the network. Multiple paths, however, result in

active loops

introduce redundant traffic to the network, which can quickly degrade overall network performance and, more importantly, breaks network rules.

. Active loops

In the example shown in Figure 1-15

, three network segments are connected by three bridges, causing an active loop. Device B transmits a packet for device E. Bridges 1 and 3 receive the packet and forward it. Device E receives the packet from bridge 1 but also receives a copy from bridge 2 (via bridge 3).

Figure 1-15 An Example Active Loop

A networking standards committee of the Institute of Electronic and Electrical Engineers (IEEE) recognized and solved the problem by introducing the

Spanning Tree Algorithm and Protocol

(STAP).

The STAP has become a standard bridge feature.

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Bridging 1-17

In a bridged network, a

root bridge

is elected to control the other bridges. The root bridge is made aware of any active loops by consulting the other bridges. The STAP constructs a

spanning tree

which provides unique paths between all devices in the network, and applies it by putting various bridges' ports in to a blocking state, as shown in Figure 1-16

Figure 1-16

Bridge Port Blocking

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The STAP is also capable of constructing a new spanning tree should the unique path fail, see Figure 1-17

, leading to quick

network recovery.

Figure 1-17 Path Fails, Bridge Port Re-enabled

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Bridging 1-19

Network resilience obviously leads to some path redundancy, as shown in Figure 1-18

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Figure 1-18

Network Resilience

For more detailed STAP information, please refer to the latest revision of the

IEEE 802.1 Part D

standard.

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Bridge Filters

The LinkBuilder MSH 4 Port Ethernet Bridge Module allows the use of transparent filtering, as explained in

Forwarding

filtering modes: Host-to-Host filtering

■

Host-to-Port filtering

■

Port-to-Port filtering

■

Multicast-to-Port filtering

■

Protocol filtering

■

Bit filtering

■

This section describes these filtering modes and filtering concepts in general.

NTRODUCTION

customised filtering

, which can be used in addition to basic

Learning, Filtering And

on page 1-12. It supports the following custom

What Is Custom Filtering?

Custom filtering

communicate through the bridge. When applied, the bridge

(discards) certain packets based on the contents of

filters

. These filter sets can be edited by the bridge operator and are

sets

used for indicating what devices' packets are to be filtered.

Figure 1-19

, Figure 1-20 and Figure 1-21 illustrate how a bridge performs custom filtering. This particular example shows host-to-port filtering.

lets you selectively define the hosts that can

filter

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Bridge Filters 1-21

Figure 1-19: A filter set for port 2 has been set up allowing device

A to communicate through the bridge and out of that port. No other device can communicate through the bridge and out of that port.

Figure 1-19

An Example Network With Filter Set

Figure 1-20: Device A transmits a packet for device C. The bridge

knows that device C is connected to port 2, so it checks that port's filter set. Communication is allowed, so it forwards the packet.

Figure 1-20

Forwards Packet

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Figure 1-21: Device B transmits a packet for device C. The bridge

knows that device C is connected to port 2, so it checks that port's filter set. Communication is not allowed, so it filters the packet.

Figure 1-21 Filters Packet

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Filter Sets

Bridge Filters 1-23

filter set

is a group of devices that are allowed to communicate with each other. The 4 Port Ethernet Bridge Module's default filter sets let all hosts and ports communicate. If you want to restrict communication, you must edit the default filter sets. Each custom filter type has specific filter sets.

Host-to-Host Filtering

host-to-host

filter set is a group of devices that are allowed to communicate through the bridge. There are 32 default host-to-host filter sets for you to use. Use each filter set for a specific group of devices, for example, if you have a set for each department in your business, it is easier to manage your filtering.

31 host-to-host filter sets are defined as One host-to-host filter set is defined as

inclusion

(sets 2 to 32).

absolute exclusion

(set 1).

Devices that are members of an inclusion set can only communicate with each other through the bridge.

The absolute exclusion set is a special set used for restricting device communication. A device that is a member of that set is prohibited from communicating through the bridge.

he default host group ensures that no host-to-host filtering

takes place before the inclusion filter sets are set up. If you set up an inclusion set, you must remove the default host

group. If you empty an inclusion set, you must replace the default host group.

The default host group must not be added to the absolute exclusion set.

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Figure 1-22 illustrates a host-to-host filter example, and shows

four network segments connected by a bridge. A filter set has been set up allowing communication between devices A and D only, through the bridge. Every packet received by the bridge has its source address and destination address checked. If both addresses match the addresses in the filter sets, the packet is forwarded.

Figure 1-22 Host-to-Host Filtering Example

Host-to-Port Filtering

Host-to-port

filters allow the user to define groups of devices that are allowed to communicate through the bridge with devices connected to a specific bridge port. There is a host-to-port filter set for each bridge port.

Host-to-port filter sets can be defined as

inclusion

exclusion

Inclusion means that devices in the set can communicate out of that port, and all other devices cannot. If the set is empty, no devices can communicate out of that port.

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Bridge Filters 1-25

Exclusion means that devices in the set cannot communicate out of that port, and all other devices can. If the set is empty, all devices can communicate out of that port.

The default host group is contained in all host-to-port filter sets following an initialization. Sets default to inclusion. The host-to-port default host represents all hosts except those defined in the host-to-port filter sets. If you include device A in a host-to-port set and delete the default host, then device A will not be able to communicate through other ports unless you also include device A in those ports' host-to-port filter sets.

Figure 1-23

illustrates a host-to-port filter example, and shows four network segments connected by a bridge. The ports' filter sets have been set up, allowing device F to communicate with devices connected to port 1, device H to communicate with devices connected to ports 1 and 3, and device C to communicate with devices connected to port E. Every packet received by the bridge has its destination address checked. If the destination addresses appears in the source address list for that port, the packet is forwarded.

Figure 1-23

Host-to-Port Filtering Example

In the example, the bridge will forward a packet from device H to device A. However, for the bridge to forward a packet from device A to device H, device A's address must be added to port E's filter set.

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Port-to-Port Filtering

port-to-port

filter set is a group of ports that are allowed to communicate through the bridge. There is a port-to-port filter set for each bridge port.

Figure 1-24

example. Figure 1-24

and Figure 1-25 illustrate a port-to-port filter

shows four network segments connected by a bridge. The ports' filter sets have been set up, allowing communication between ports 1 and 2, ports 1 and E, and ports 2 and 3.

Figure 1-24 Port-to-Port Filtering Example

Figure 1-25 shows the port communications that are allowed.

Figure 1-25 Allowable Port Communication

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Bridge Filters 1-27

Changes made to port-to-port filter sets are mirrored by the other port-to-port filter sets. For example, if ports 1 and E are added to port 3's filter set, port 3 is automatically added to port 1's and port E's filter sets.

Multicast-to-Port Filtering

multicast-to-port

filter set is a group of ports that are allowed to send and receive broadcast and multicast packets from a specific bridge port. There is a multicast-to-port filter set for each bridge port.

The multicast-to-port filter sets operate in exactly the same manner as the port-to-port filter sets, the only difference being that multicast-to-port filter sets are used for broadcast and multicast packets only.

Protocol Filtering

protocol

filter set is a group of network protocol filters for which the bridge will permit or deny the forwarding of packets to a specific bridge port. There is a protocol filter set for each bridge port.

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For example, if you want to prevent packets using the TCP/IP protocol from being forwarded to the network segment connected to port 2, you would edit port 2's protocol filter set to deny the TCP/IP protocol.

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1: I

Bit Filtering

Bit filters

selectively filter out traffic based on bit values occurring in the first 64 bytes of each frame. This provides extremely flexible filtering. You can test any combination of bits within a six-byte long field falling within the first 64 bytes of the frame and beginning on a byte boundary. You can have up to five input filters and five output filters.

When you set up a bit filter, you define a

bit pattern

. The bit

pattern consists of up to 48 bit values (1 or 0), for example,

10111001. The bridge compares this pattern against the pattern found in a specified location for every packet. If the patterns match, the bridge filters or forwards the packet as specified by additional filter information.

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Enabling Custom Filtering

You have to enable custom filtering before it becomes effective. You can enable and disable all custom filters or individual custom filters with ease.

As custom filtering can involve multiple checking of packets, it can have an adverse impact on bridge performance in a high traffic rate environment. Therefore, it is best to plan custom filtering carefully, enabling filters only as necessary.

The 4 Port Ethernet Bridge Module performs filtering tests in a specific order:

Multicast-to-Port filtering

Port-to-Port filtering

Host-to-Port filtering

Host-to-Host filtering

Bridge Filters 1-29

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Protocol filtering

Bit filtering

In mathematical terms, the filtering operation is characteristic of a logical OR. If the filter sets of any one type indicate that a packet should be filtered out, the bridge will discard it and perform no further tests. You can improve bridge performance by using higher precedence filters when possible.

For example, you may set up port-to-port filter sets to filter out packets between ports 1 and 2. You may then create a host-to-host filter set that includes a device connected to port 1 and a device connected to port 2. These devices will not be able to communicate because their packets will be filtered out by port-to-port filtering.

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Simple Network Management Protocol (SNMP)

SNMP is an application-level protocol for managing products such as bridges on TCP/IP networks. You can issue SNMP application. The application passes the requests to the SNMP agent software on the device to be managed. The agent carries out the requests and sends

responses

Requests and responses are referred to as

The SNMP agent on the bridge allows it to be managed by any SNMP application. This agent complies with RFC 1157,

Network Management Protocol

The agent performs network management functions based on GET and SET operations. These operations retrieve and store values of variables belonging to the managed device. The variables are defined in one or more

(MIBs).

Bases

Management Information

MIB variables are encoded in a subset of the data-description language rules specified by the

Abstract Syntax Notation One

Structure of Management Information

(SMI). In SMI and ASN.1 terms, a MIB contains which has an assigned unique name, known as an

identifier

(OID).

requests

to the application.

SNMP messages

(ASN.1), according to the

objects

using an

A Simple

, each of

object

The names actually used in your management application to refer to MIB variables depend entirely on that application and may be different to OIDs.

The bridge supports the following MIBs:

Internet Standard II, as defined in RFC 1158,

■

Management

Information Base for TCP/IP-Based Internets

Internet Bridge MIB, as defined in RFC 1286,

■

Internet Ethernet MIB, as defined in RFC 1284,

■

Bridge MIB

Definitions of

Managed Objects for the Ethernet like Interface Types

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Installation And Removal

Installation And Removal 1-31

WARNING:

Please read the following safety and anti-static information before removing the module from its anti-static packaging.

Safety Information

To avoid having dangerous equipment:

■

Installation of this module should be carried out by qualified personnel only.

■

This module operates under SELV conditions (Safety Extra Low Voltage) according to IEC 950, the conditions of which are maintained only if the equipment to which it is connected is also operational under SELV.

■

The LinkBuilder MSH chassis must be earthed.

Anti-Static Information

To avoid damaging the module:

■

Do not remove the module from its anti-static packaging until you are ready to install it into the LinkBuilder MSH chassis.

■

Do not touch the pins, leads, connections or any components on the module.

■

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Handle the module only by its edges. Always wear an anti-static wristband connected to a suitable

earth point. Always store and transport the module in anti-static packaging.

Please refer to the

MSH/11

manual for information on installing and removing the

How To Install And Use The LinkBuilder

bridge module.

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■ The VT100 Management Interface

■ The VT100 Bridge Menu Map

■ Bridge Control Keys

■ Simple Bridge Configuration

■ IP Address Configuration

■ SNMP Configuration

ETTING STARTED

This chapter contains the following topics:

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Introduction

This chapter describes setting up the bridge for the first time. If you have not set up the bridge before, or are setting it up again after initializing NVRAM, you should read this chapter.

The chapter contains the following information:

A general introduction to the VT100 Management Interface,

■

which is used to manage the bridge. A description of how to configure a simple bridge that connects

■

up to four network segments. This configuration involves:

■

ETTING STARTED

2: G

Logging on and off the bridge Establishing operator accounts Defining bridge information Saving and making changes effective Erasing all the changes

A descrption of how to assign an IP address to the bridge so that

■

the bridge can be managed remotely via Telnet. This involves:

■

Setting up IP addresses

■

Using Telnet for remote connections

■

Using the Packet Internet Groper (PING) program to test connections

A description of how to configure the SNMP agent on the bridge

■

so that SNMP applications can obtain information about the bridge. This involves:

■

Configuring the basic characteristics of each community and globally enabling or disabling the Authentication Failure Trap

■

Enabling traps for individual communities and specifying the IP addresses where the traps should be sent

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The VT100 Management Interface 2-3

The VT100 Management Interface

The VT100 management interface is used for bridge management. The screens are based on forms and are controlled using special interface control keys.

The bridge has different control keys to the MSH management module. When you log on to the bridge, the bridge control keys take over. The bridge control keys are described in Bridge Control

Keys on page 2-8.

The screens are grouped hierarchically. For a complete menu map of the bridge screens, see

2-6. The menu map also appears on

Ethernet Bridge Module 3C18600 Quick Reference Guide

accompanies this manual.

This chapter assumes that you are familiar with the VT100 management interface.

The VT100 Bridge Menu Map

on page

The LinkBuilder MSH 4 Port

, that

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Please refer to

The LinkBuilder MSH Management Module

manual for information on connecting VT100 and VT100 via Telnet. The manual also describes VT100 screen conventions and VT100 control keys.

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The VT100 Bridge Screens

The VT100 bridge screens have the same general layout. The components of a bridge screen are shown in Figure 2-1

Figure 2-1 Bridge Screen Components

The components are:

A - Screen title.

The boxed words starting in the top left hand

corner of the screen.

B - Highlight.

A dark or bright bar over the input field that

receives the information you enter into the input area.

C - System name.

The name you give your bridge on the

System Information screen.

D - Local login identifier.

The name of the user currently locally

logged on to the bridge.

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The VT100 Management Interface 2-5

E - Remote login identifier.

The name of the user currently

remotely logged on to the bridge.

F - Input area.

The line below the screen area provides the data entry location for input screens. The area starts with a short description of the highlighted field. You enter the value in the input area, where you can change or correct your typing as necessary. When you press [Enter] or [Return], your input area appears in the highlighted field. Your terminal may beep for an inappropriate entry.

G - Prompt.

The small blinking box that shows where you are in

the input area.

H - Message area.

The line underneath the input area that displays useful information. It usually displays the bridge's software version and release date. If you make an error, it displays a reason.

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The VT100 Bridge Menu Map

The VT100 bridge menu map, as shown in Figure 2-2, shows the links between the bridge management screens. The at the bottom left of each screen box is the page in this manual, where you will find the description of that screen.

italic number

Figure 2-2 The VT100 Bridge Menu Map

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The VT100 Bridge Menu Map 2-7

Operators with Administrator privileges are unrestricted. Operators with Operator privileges cannot configure the bridge, initialize NVRAM, or reset the bridge (the Administrative Screens).

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Bridge Control Keys

There are special control keys for operating the bridge. These are different to the MSH management module control keys and should be used from the time you log on to the bridge. For [Ctrl] key sequences, hold down the [Ctrl] key while pressing the specified key. For [Esc] key sequences, press [Esc] and then press the specified key.

The bridge control keys are described in Table 2-1

Table 2-1 Bridge Control Keys

Key Description Help

[?] [Esc] [H] Displays a help screen. Many screens have their own

Quick keys

letters Selects the menu item preceded by the character.

Select or confirm entry

[Return] [Enter] Selects the current menu item or confirms the entry

Previous screen

[Ctrl] + [Z] [Esc] [P]

help screens. The general help screen appears for screens without specific help screens.

You do not need to press [Return]. For example, [B] will take you from the Main Menu to the Configuration menu. [B] [A] [A] will take you from the Main Menu to the System Information screen.

for a field and moves to the next entry field.

Returns you to the previous screen or menu.

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Bridge Control Keys 2-9

Table 2-1

Bridge Control Keys

Key Description Return to Main Menu

[Ctrl] + [T]

Returns you to the Main Menu. [Ctrl] + [C] [Ctrl] + [Y] [Esc] [T]

Return to MSH Management Module

[Ctrl] + [P] When logged on locally, this returns you to the MSH

Management Module screens. We recommend you

log off the bridge before entering this command.

Move up

[Up Arrow] Selects the previous menu item or highlights the

previous entry field.

Move down

[Down Arrow] Selects the next menu item or highlights the next

entry field.

Move left

[Left Arrow] Moves the cursor left one character in the entry field.

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Move right

[Right Arrow] Moves the cursor right one character in the entry

field.

Delete character

[Backspace] [Delete] [Ctrl] + [D]

Deletes the character to the left of the cursor in the

entry field. [Ctrl] + [D] has a different use when the

extended bridge control keys are in use.

Delete all

[Ctrl] + [U] Delete all the input in the entry field.

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Table 2-1 Bridge Control Keys

Key Description Refresh screen

[Ctrl] + [V] [Esc] [V]

Next step

[Esc] [N] Takes you to the next menu or screen, or returns you

Interrupt Telnet

[Break] Interrupts a Telnet connection without waiting for it

Resume serial communication

[Ctrl] + [Q] Resumes serial communication if accidentally turned

Refreshes the screen.

from help. Using this from a menu, takes you to the screen associated with the highlighted item.

to time out.

off (XOFF).

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Simple Bridge Configuration

This section describes how to configure a simple bridge that connects up to four network segments.

Ensure all bridge connections are in place before you start.

Initially, the bridge has no IP address. Without a unique IP address, it cannot be remotely managed, so you must first log on to the LinkBuilder MSH, then log on to the bridge, then set up a unique IP address.

This simple configuration describes:

■

Logging on and off the bridge

■

Establishing operator accounts

■

Defining bridge information

■

Saving and making changes effective

Simple Bridge Configuration 2-11

■

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Erasing all configurations

You will need to configure the bridge for your particular installation. Write down all the changes that you make, so you have a configuration record. We recommend that before configuration, you look at the different bridge screens to understand how they are linked and what information they require.

Most screens have their own help screen. If a screen does not have one, the general help screen is displayed.

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Logging On To The LinkBuilder MSH

Logging on to the LinkBuilder MSH is also described in

LinkBuilder MSH Management Module

manual.

The

Connect to the LinkBuilder MSH. The Main Banner appears, as shown in Figure 2-3

Press [Enter] to continue.

Figure 2-3 LinkBuilder MSH Main Banner

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Simple Bridge Configuration 2-13

The Logon screen appears and stays displayed until a valid User Name and Password have been entered, as shown in Figure 2-4

Enter a User Name and Password for the LinkBuilder MSH.

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Figure 2-4

LinkBuilder MSH Logon Screen

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When you are logged on to the LinkBuilder MSH, the Main Menu appears, as shown in Figure 2-5

. It offers various LinkBuilder MSH management options. The LOGOFF option closes down the session, allowing the interface to ‘sleep’.

Select SERVICE SELECTION.

Figure 2-5 LinkBuilder MSH Main Menu

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Simple Bridge Configuration 2-15

The Service Selection screen appears, listing all the services within the LinkBuilder MSH Chassis with the number of the slot or backplane to which it is attached, as shown in Figure 2-6

Highlight 4 PORT .3 BRIDGE, press [Space] and select

to select

the LinkBuilder MSH 4 Port Ethernet Bridge Module.

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Figure 2-6

LinkBuilder MSH Service Selection

If the 4 Port Ethernet Bridge Module does not appear, either the module is self-testing, has been incorrectly installed, or the MSH management agent software is not version 2.1 or later.

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The Address Table screen appears, showing default address information for the bridge, as shown in Figure 2-7

. If the bridge's

IP address is unconfigured, a random IP address is shown.

Select MANAGE to continue.

Figure 2-7 LinkBuilder MSH Address Table

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Logging On To The Bridge

When you connect to the bridge, the Operator Login screen appears, as shown in Figure 2-8 has no Operator IDs or Passwords, meaning that the bridge has no security. You must set up an administrator account before any security becomes active. This configuration includes this set up.

If no accounts have been set up, press [Enter] for both fields.

If you have an account with administrative privileges, enter the Operator ID and Password. If you have accounts with administrative privileges but have forgotten the Operator IDs and Passwords, you may have to reset the bridge's configuration to default values, see Appendix A.

Simple Bridge Configuration 2-17

. Until it is configured, the bridge

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Figure 2-8

Operator ID:

Operator Login

Text Field. The operator ID is a string of one to

eight alpha-numeric characters and is case sensitive.

Password:

Text Field. The password is a string of one to eight alpha-numeric characters and is case sensitive. One for each character typed.

will appear

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Establishing Operator Accounts

When you have logged on to the bridge, the bridge's Main Menu appears, offering various management options, as shown in

Figure 2-9

The bridge's security is disabled if no administrative operator accounts have been set up, so you should set up these accounts first.

Select CONFIGURATION.

Figure 2-9 Main Menu

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Simple Bridge Configuration 2-19

The Configuration menu appears, as shown in Figure 2-10. You can access all the configuration screens and sub-menus from this menu.

Select SYSTEM.

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Figure 2-10

Configuration Menu

The System menu appears.

Select OPERATOR ACCOUNTS from the System menu.

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The Operator Accounts screen appears, listing the operator accounts that are set up for the bridge, see Figure 2-11. You can set up 60 operator accounts for the bridge.

Enter the number of the operator account you want to set up.

Figure 2-11 Operator Accounts

Display Field. The account numbers of the 60 accounts.

No:

Account:

Display Field. The operator ID for the account. This can be changed with the Edit User Accounts screen that follows on from this screen. Blank entries indicate that the account has not been assigned.

Display Field. The designated privilege for the account.

Priv:

for administrator and

is for operator. Accounts with operator

privilege cannot configure the bridge, initialize NVRAM, or reset the bridge.

Security checking is disabled if no operators are allocated administrator privileges. This prevents a lock out from configuration areas.

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Simple Bridge Configuration 2-21

Account Number:

Text Field. Enter the account number of the operator you want to set up. You can set up from 1 to 60 accounts. After entering an account number, the Edit User Accounts screen appears.

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The Edit User Accounts screen appears with information on the operator account you entered in the Operator Accounts screen, as shown in Figure 2-12

. You use this screen for entering and modifying operator account information. Any existing information is displayed.

Set up operator accounts by entering an Operator ID, Operator Privilege and Password (repeat the Password for verification). To set up a different operator account, enter its Account Number. When you have finished, return to the System menu.

Figure 2-12 Edit User Accounts

Account Number:

Text Field. The number of the operator account. To configure a different account, enter its account number and the Edit User Accounts screen changes to display this account's information. This saves having to return to the Operator Accounts screen. The account number can be from 1 to 60.

Operator ID

Text Field. The operator's ID is a string of one to

eight alpha-numeric characters. When entered elsewhere, the operator ID is case sensitive. Changes to this field are only saved during a bridge reset, and take effect from then on.

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Simple Bridge Configuration 2-23

Operator Privilege:

for the operator.

is for administrator and O is for operator.

Choice Field (

/ O). Designate the privileges

Bridge operators can be set up with either Administrator or Operator privileges. Operators with Administrator privileges are unrestricted. Operators with Operator privileges cannot configure the bridge, initialize NVRAM, or reset the bridge.

Security checking remains disabled if no operators are allocated administrator privileges. This prevents a lock out from administrative areas.

Changes to this field are only saved during a bridge reset, and take effect from then on.

Password:

Text Field. The password is a string of one to eight alpha-numeric characters. When entered elsewhere, the password is case sensitive. One

will appear for each character typed. Changes to this field are only saved during a bridge reset, and take effect from then on.

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Adding Bridge Information

You should provide general device information for your bridge the first time you set it up. This information is required by all MIB II conformant devices and is generally useful because it includes the location of the bridge and the name of the person responsible for it (useful if the bridge is not operating correctly).

Select SYSTEM INFORMATION from the System menu.

The System Information screen appears, as shown in Figure 2-13 You use this screen for entering and modifying device information. Any existing information is displayed.

Enter the information and, when you are sure it is correct, return to the Configuration menu.

Figure 2-13 System Information

System Name:

Text Field. Enter a name for the bridge. This is a string of 1 to 16 characters. Changes to this field are only saved during a bridge reset, and take effect from then on.

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Simple Bridge Configuration 2-25

System Contact:

Text Field. Enter the name of the person who is responsible for the bridge. This is a string of 1 to 16 characters. Changes to this field are only saved during a bridge reset, and take effect from then on.

System Location:

Text Field. Enter the physical location of the bridge. This helps if ever it needs to be located. This is a string of 1 to 16 characters. Changes to this field are only saved during a bridge reset, and take effect from then on.

Local Time/Date:

Text Field. Enter the local time and date. Changes to this field are only saved during a bridge reset, and take effect from then on.

Local Control Terminal Port Mode:

be set to

standard

. Do not change this field.

Remote Control Terminal Port Mode:

should be set to

Bridge Statistics Averaging:

standard

. Do not change this field.

Tex t F ie ld (

Text Field. This field should

Text Field. This field

off

). Set the method by which statistics are displayed on the Bridge Statistics and Bridge Port Statistics monitoring screens. If you want the accumulated statistics averaged per second, specify

. If you

want the total accumulated statistics (since power up), specify

off

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Saving And Making Changes Effective

Some of the changes you can make to the bridge are not saved if you simply log off. However, not all fields require a bridge reset to save them and make them effective. The field descriptions that accompany each screen, in this manual, describe the necessary procedures.

Any changes that are saved, are saved in NVRAM (Non Volatile Random Access Memory). Changes in NVRAM are remembered over a power cycle.

Select BRIDGE RESET from the Configuration menu.

The Bridge Reset screen appears, as shown in Figure 2-14

. It reminds you of its effect and prompts you for a yes/no answer. Enter

to reset the bridge or no to return to the Configuration

yes

menu.

Figure 2-14 Bridge Reset

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Erasing All Changes

If you want to erase all the changes made to the bridge since logging on, simply log off the bridge. However, if you want to erase all the changes ever made to the bridge, you must initialize NVRAM (Non Volatile Random Access Memory) and reset the bridge. If you initialize NVRAM but do not reset the bridge, logging off instead, the changes will not be erased.

Select INITIALIZE NOVRAM from the Configuration menu.

Simple Bridge Configuration 2-27

The Initialize NOVRAM screen appears, as shown in Figure 2-15 warns you of its effect and prompts you for a yes/no answer.

yes

Enter

to agree to initializing NVRAM or no to return to the

Configuration menu.

If you enter

yes

, the Reset Bridge screen appears. This screen

warns you of its effect and prompts you for a yes/no answer.

yes

Enter

to initialize NVRAM or no to return to the

Configuration menu.

. It

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Figure 2-15

Initialize NVRAM

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Logging Off The Bridge

Selecting LOGOUT from the Main Menu will log you off the bridge and return you to the display you had before logging on. Any changes that have been made since logging on will be erased. Most fields, but not all, require a bridge reset to save them and make them effective, see

Effective

on page 2-26.

We recommend that you log off the bridge before returning to the MSH Management Module screens.

Saving And Making Changes

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IP Address Configuration

This section describes how to assign an IP address to the bridge. When the bridge has an IP address, you can remotely manage it via Telnet, and will not need to go through the LinkBuilder MSH. Telnet is a TCP/IP application. SNMP also requires the bridge to have an IP address.

This simple configuration describes:

■

Setting up IP addresses

■

Using Telnet for remote connections

■

Using PING to test connections

Every IP network device is identifiable by its unique IP address (Internet Protocol address). An extension to the IP addressing scheme allows you to divide networks into subnetworks. The subnet mask identifies which parts of the IP address denote the network (network number) and which denote the host (host number).

IP Address Configuration 2-29

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IP devices can only communicate with devices on different networks via IP routers (gateways). A subnet mask is not needed unless the network is IP routed.

If you have a private IP network, you can assign any IP address you like. However, if you are connecting to the Internet, your IP address must be unique. Network numbers can be assigned by the Network Information Center (NIC). This organization assigns a globally unique network number to each network that wishes to connect to the Internet. The host numbers are then assigned by your local system administration.

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Bridge Connections

The Telnet protocol is used for remotely logging on to a device. The following requirements must be met for remote login:

You must have an account on the host and you must know the

■

operator ID and password for that account. You must know either the host name or IP address of the host.

■

You can only use the host names configured in your local IP Host Table screen.

If you are logging on from a remote host, the terminal must

■

support VT100.

Logging On To The Bridge

You can log on to the bridge locally (via the LinkBuilder MSH) and remotely (via Telnet). The bridge can accept:

Either a local or a remote log on.

■

Both a local and a remote log on.

■

The bridge cannot accept:

Multiple local or remote log ons.

■

Telnet From The Bridge

The bridge has Telnet capabilities, allowing you to Telnet from the bridge to another device. The bridge allows you to:

Telnet from the bridge if you have locally logged on. The bridge

■

can still accept a remote log on.

The bridge does not allow you to:

Have multiple Telnet sessions from the bridge.

■

Telnet from the bridge if you have remotely logged on.

■

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Setting Up Remote Access

Initially, the bridge has no IP addressing information. When set up, the IP address identifies the bridge. The IP Addresses screen is used for setting up an IP address for the bridge so that other devices can communicate with its management agent.

Select CONFIGURATION from the Main Menu. Select NETWORK PROTOCOL from the Configuration menu. Select IP ADDRESSES from the Network Protocol menu.

The IP Addresses screen appears, displaying two tables, Active and Next Reset, as shown in Figure 2-16 the IP Address and Subnet Mask that are currently used. The Next Reset table allows you to enter a new IP Address and Subnet Mask, which will be used after the bridge is next reset. Highlight the field you wish to change and an area for entering the new information will appear at the bottom of the screen.

Enter your address information. A Subnet Mask is not needed unless the network is IP routed. After entering your information, the IP Address screen asks if you want to reset the bridge. Ignore this and reset the bridge when you've completed this section.

IP Address Configuration 2-31

. The Active table shows

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Figure 2-16

IP Addresses

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IP Address:

Display Field. The bridge's current IP address. A line of dashes indicates that no IP address has been assigned to the bridge.

Subnet Mask:

Display Field. The bridge's current subnet mask.

Next Reset

IP Address:

Text Field. Enter the IP address you want to assign to the bridge. It must be unique and of the form nnn.nnn.nnn.nnn (decimal). Enter

0.0.0.0

to remove the bridge's IP address. Changes to this field are only saved during a bridge reset, and take effect from then on.

Subnet Mask:

Text Field. Enter the subnet mask you want to assign to the bridge. A subnet mask is not needed unless the network is IP routed. It must be of the form nnn.nnn.nnn.nnn (decimal). Changes to this field are only saved during a bridge reset, and take effect from then on.

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IP Address Configuration 2-33

Static Routes

If you are using a routed network, you will need to enter a default gateway to ensure remote communication with the bridge. A more resilient network can be set up by defining a set of

routes

. Static routes are predefined routes, with different levels of

static

priority, through the routed network. The highest priority route will be used until a router or cable goes down, breaking the route. When this happens, the next priority route is used.

Select IP STATIC ROUTES from the Network Protocol menu.

The Static Routes screen appears, as shown in Figure 2-17

. You use this table to specify gateways the IP router should use to reach specific network, host or subnet destinations.

Each static route includes a preference value. If protocols are enabled, the preference you specify in a static route to a network or subnet destination is compared to preference values for the same destination learned through protocol messages from the network. If the static route preference value is higher (less desirable) than a route learned over the network, the static route is replaced. However, since the protocols deal only with network (or subnet) destinations, enabling them does not change any static routes that you specify for hosts.

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Figure 2-17

Static Routes

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Item:

Text Field. The number of a configured static route or

(to enter a new route). Static routes are sorted by IP address and assigned numbers according to their positions in the sorted list. Entering the number of a configured static route causes that route to be displayed.

Destination Host:

Text Field. The IP address of a network, host, or gateway, or a [Space] character, or the keyword default. Specify the address in decimal notation, nnn.nnn.nnn.nnn. If a host name has been defined in the IP Host Table screen, you can use that name rather than the IP address.

The IP address can be an address that is configured in a static route, or an address for a new route. If the address is already configured, entering it causes its parameters to be displayed on the line you can edit. If it is not configured, the remaining fields in the line are blank.

A [Space] character deletes the route displayed. Item numbers are adjusted accordingly.

default

is equivalent to the address

0.0.0.0

, which is the destination for the default gateway. In other words, the gateway you specify for this destination is the one that will be used for any route not defined in the routing table.

Enter

for the SAVE CHANGES? field to save changes to this

field. Changes only take effect after a bridge reset.

Gateway:

Text Field. The IP address or host name of the gateway that is the next hop for the destination host specified in the previous field. If a host name is given, it must be defined in the IP Host Table screen. Enter

for the SAVE CHANGES? field to save

changes to this field. Changes only take effect after a bridge reset.

DUA1860-0AAA01

IP Address Configuration 2-35

Preference:

Text Field. A whole number from 0 to 255, designating the rank to be assigned to the route specified by the DESTINATION HOST and GATEWAY fields.

255

desirable route, default is

. Enter y for the SAVE CHANGES? field to save

represents the least desirable route. The

represents the most

changes to this field. Changes only take effect after a bridge reset.

Save changes?:

Text Field. Enter

this screen to NVRAM, or

to not save any changes. Changes

to save any changes made to

only take effect after a bridge reset.

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Assigning Host Name / IP Address Pairs

You can assign symbolic names (

host names

) for devices that can communicate with or from the bridge. If a device has an IP address, a host name can be assigned to it. This host name can then be used instead of the IP address to identify the device, when using the bridge. It is not necessary to assign host names, but they are a lot easier to remember than IP addresses. The IP Host Table screen is used for assigning IP address / host name pairs and is primarily used for Telnet.

Select HOST TABLE from the Network Protocol menu.

The IP Host Table screen appears, displaying two tables, IP Addresses and Host Name, as shown in Figure 2-18

. The Host Name table lists the existing host names assigned to the corresponding IP address in the IP Addresses table.

Enter IP address / host name pairs for devices that can access the bridge. The host name must be unique for each device. For a bridge, use the name defined in its System Information screen as its host name.

Figure 2-18 IP Host Table

DUA1860-0AAA01

IP Address Configuration 2-37

IP Address:

Text Field. Enter the IP address for the device. It must be in decimal and of the form nnn.nnn.nnn.nnn. Changes to this field are only saved during a bridge reset, and take effect from then on.

Host Name:

Text Field. Enter the host name for the device. Changes to this field are only saved during a bridge reset, and take effect from then on.

The IP Host Table screen is updated with any new IP address / host name pairs that are entered in the custom filtering screens.

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Using PING To Test Connections

The PING (Packet InterNet Groper) program checks for a valid connection to a network device. Any device with an IP address can respond to a PING session. It tests network connections by sending packets to a specified IP address and checking the response.

If you have just set up address information for the bridge, reset the bridge to save the information and for it to take effect.

We recommend that you PING the LinkBuilder MSH Management Module, in the same chassis as the bridge, to test that PING is working correctly.

You could use PING if:

You can't connect to a remote device and are unsure if it is

■

working. There is a problem on the network and you need to check all the

■

nodes for response quickly.

If you get no response from a device, it could be because:

You are using the wrong IP address.

■

No one has assigned the IP address to the remote device or, if a

■

host name was used, the host name is not assigned to that IP address in the bridge's host table. You may wish to contact someone at the remote site.

The host is shut off or has crashed. You may wish to contact

■

someone at the remote site. Your subnet mask is wrong.

■

The default gateway is wrong.

■

You have not assigned an IP address to the bridge.

■

DUA1860-0AAA01

IP Address Configuration 2-39

Select PING from the Applications menu.

The Ping Settings screen appears, as shown in Figure 2-19

. Enter the IP address or host name of the remote device and confirm the packet size and timeout parameters (modify these only if necessary).

Figure 2-19

Destination IP address:

Ping Settings

Text Field. Enter the IP address for the remote device. It must be in decimal and of the form nnn.nnn.nnn.nnn.

DUA1860-0AAA01

or Enter the host name for the remote device. This host name must

be in the host table of your bridge.

Packet Size:

Text Field. The number of bytes in the packet,

excluding the header, that contains the echo request message.

Timeout:

Text Field. The number of seconds PING waits for an ICMP echo response message, before giving up and sending the next ICMP echo request message.

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The Ping screen appears, as shown in Figure 2-20, after the information for the Ping Settings screen has been supplied. The Ping screen immediately starts displaying status messages when information is received.

When you've finished with the Ping screen, press [Enter] or [Return] to exit from it.

Figure 2-20 Ping

Destination:

Display Field. The IP address or host name of the

remote device being pinged.

Packet Size:

Display Field. The number of bytes in the packet,

excluding the header, that contains the echo request message.

Timeout:

Display Field. The number of seconds PING waits for an ICMP echo response message, before giving up and sending the next ICMP echo request message.

Packets Sent:

Display Field. The number of ICMP echo request

messages that have been sent to the destination address.

DUA1860-0AAA01

IP Address Configuration 2-41

Packets Received:

Display Field. The number of ICMP echo response messages that have been received from the destination address.

Minimum:

Display Field. The shortest amount of time (in milliseconds) that elapsed between sending an ICMP echo request and receiving an ICMP echo response.

Average:

Display Field. The average amount of time (in milliseconds) that elapsed between sending an ICMP echo request and receiving an ICMP echo response.

Maximum:

Display Field. The longest amount of time (in milliseconds) that elapsed between sending an ICMP echo request and receiving an ICMP echo response.

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Telnet Log On To Another IP Device From The Bridge

The bridge has Telnet capabilities, allowing you to remotely log on to an IP device. This is especially useful for logging on to other LinkBuilder MSH 4 Port Bridge Modules. However, the bridge does not always allow you to Telnet out. For information on when you can Telnet, see

Bridge Connections

on page 2-30. You may

wish to Telnet to the LinkBuilder MSH Management Module.

Select APPLICATIONS from the Main Menu. Select TELNET from the Applications menu, to start a Telnet session.

One of the following will happen:

If the Connections menu appears, the bridge has already

■

accepted a remote log on. You are not allowed to Telnet out from the bridge.

If you are remotely logged on to the bridge, you can talk to a local user (the user who has logged on to the bridge locally), if present, by using the Chat screen (select CHAT W. LOCAL to display this screen). When you have finished, select END CONNECTION.

If you are locally logged on to the bridge, you can talk to a remote user (the user who has logged on to the bridge remotely), if present, by using the Chat screen (select CHAT W. REMOTE to display this screen). When you have finished, select END CONNECTION.

DUA1860-0AAA01

IP Address Configuration 2-43

■

If the Remote Connect screen appears, as shown in Figure 2-21, you are allowed to Telnet out from the bridge. Enter the host name or IP address of the device you want to log on to. If you use a host name, it must appear in the bridge's host table. If you use an IP address, it must be in the decimal form nnn.nnn.nnn.nnn.

DUA1860-0AAA01

Figure 2-21

Remote Connect

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Talking To Another Bridge User

The bridge can accept two users, one local and one remote. If both users are present, they can exchange messages via the Chat screen.

The Chat screen, as shown in Figure 2-22

, is intended for

exchanging uncomplicated information:

Warning the other user that you are about to reset the bridge or

■

change its configuration. Exchanging telephone numbers so you can discuss any network

■

issues you may have.

The local user can get the Chat screen by selecting CHAT W. REMOTE from the Connections menu. The remote user can get the Chat screen by selecting CHAT W. LOCAL from the Connections menu.

Figure 2-22 Chat

Message:

Text Field. Enter your message for the other user. It

can be up to 50 characters long.

DUA1860-0AAA01

IP Address Configuration 2-45

Telnet Suspension

You can suspend your Telnet session from the bridge at any time. You may want to do this if you want to return to the bridge but stay connected to the remote device.

To suspend a remote session, press [Ctrl] + [ ] ]. You will be returned to the Main Menu of the bridge. To resume a suspended session, press [Ctrl] + [ ] ] again.

Tel ne t L og Off

To disconnect from the remote device, select END CONNECTION from the Connections menu. The Terminate Connection screen appears, displaying the IP address and host name of the remote host you wish to disconnect from, as shown in Figure 2-23

If you want to disconnect from the remote device, press [Enter] or [Return]. If you do not want to disconnect from the remote device, leave the screen.

DUA1860-0AAA01

Figure 2-23

Terminate Connection

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SNMP Configuration

This section describes configuration of the bridge. When the SNMP agent has been configured, SNMP applications can obtain information from it about the bridge.

This section describes how to:

Configure the basic characteristics of each community and

■

globally enable or disable the Authentication Failure trap. Enable traps for individual communities and specify the IP

■

addresses to which the traps should be sent.

The basic concepts of SNMP are explained in

Algorithm And Protocol (STAP)

Remember to reset the bridge after setting up the SNMP agent if you want your configuration to be saved and take effect.

Community Administration

The bridge has a

community

administrative relationship between a SNMP agent it wishes to communicate with.

On the bridge, for the community you must configure:

SNMP agent

Spanning Tree

on page 1-16.

. A community defines an

(a device) and the

client

on the

community name

■

used by the client and agent as a password for communicating with each other and included in all messages exchanged between them.

■

MIB view

defining the subset of MIB variables that can be

accessed by client requests containing the community name. An

■

access mode

specifying whether client requests containing the community name can perform read only (GET) operations, or read and write (GET and SET) operations on MIB variables.

DUA1860-0AAA01

Traps

SNMP Configuration 2-47

An SNMP agent can send messages,

traps

, when exceptional events occur. Traps include the name of the community involved in the event. They are sent to an IP address that you define for each community during configuration of the agent.

The main advantage of traps is that you do not have to constantly monitor the bridge because it alerts you when any exceptional events occur.

The bridge's SNMP agent supports the following bridge traps:

■

Authentication Failure An SNMP client has tried to access the agent using a community

name the agent does not recognize, or requesting an action not allowed for the community.

■

Cold Start The agent is initializing itself. The values of MIB variables may

change.

■

Interface Up A port, previously not operational, is now operational.

■

Interface Down

■

DUA1860-0AAA01

A port, previously operational, is now not operational. New Root The bridge on which the agent is running has become the new

root of the Spanning Tree. Topology Change One of the configured bridge's configured ports has gone into or

out of the Forwarding state. This could be due to STAP or manual configuration.

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Configuring Basic Community Characteristics

Select CONFIGURATION from the Main Menu and then NETWORK PROTOCOL from the Configuration menu. Select SNMP from the Network Protocol menu to get the Configure SNMP menu.

Select COMMUNITIES from the Configure SNMP menu.

The SNMP Community Basic Configuration screen appears, as shown in Figure 2-24

. You use this screen for enabling or disabling the authentication trap for the SNMP agent running on the bridge. You would also use this screen for configuring the community name, MIB view, and SNMP access mode for the community that will access the SNMP agent.

Figure 2-24 SNMP Community Basic Configuration

DUA1860-0AAA01

SNMP Configuration 2-49

Authentication Failure Trap:

Text Field ( the authentication failure trap for the SNMP agent. Enter enable, or enter

to disable. The default is disable.

/ d). Enable or disable

If the trap is enabled, the agent generates a trap message whenever a client tries to access it using a community name you have not defined. The message is sent to the trap destination of each community for which traps are enabled. Use the SNMP Community Trap Configuration screen to enable all traps, and define the destinations that are to receive messages reporting traps.

If the trap is disabled, no authentication failure trap messages are generated, regardless of whether or not traps have been enabled on the SNMP Community Trap Configuration Screen.

Changes to this field are only saved during a bridge reset, and take effect from then on.

Community Name:

Text Field. A community name is a name by which a client can access this agent. If the field is blank, you can use it to add a community name. The name can contain from 1 to 32 characters.

Press [Space] to delete a community name. The default is blank.

DUA1860-0AAA01

Changes to this field are only saved during a bridge reset, and take effect from then on.

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Access:

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Tex t F ie ld (

r/o

). Enter the access mode for the

r/w

community's MIB view. The effect this has on operations permissible for the community depends on the ACCESS: in the MIB definition of the object.

Enter

to specify that the community can perform read

r/o

operations (GET and TRAP) on the value of a MIB object in the MIB view, if the object's MIB ACCESS: is

read-only write-only

. The value of an object whose ACCESS: is

not-accessible

cannot be read. No object

read-write

values can be written (SET). Enter

to specify that the community can perform read and

r/w

write operations (GET, TRAP and SET) on the value of any object in the MIB view, if the object's MIB ACCESS: is

write-only

The default is

r/o

read-write

Changes to this field are only saved during a bridge reset, and take effect from then on.

DUA1860-0AAA01

Configuring Community Traps

Select COMMUNITY TRAPS from the Configure SNMP menu.

The SNMP Community Trap Configuration screen appears, as shown in Figure 2-25 (configured in the SNMP Community Basic Configuration screen). You use this screen for configuring the community name, enabling or disabling traps, defining the device to which the agent is to send trap messages, and defining the UDP port to which the agent is to send trap messages.

SNMP Configuration 2-51

, displaying the existing community name

DUA1860-0AAA01

Figure 2-25

Community Name:

SNMP Community Trap Configuration

Text Field. The name of the SNMP community. If this field is blank, you can enter a new community name. The name can be 1 to 32 alpha-numeric characters.

Press [Space] to delete a community name. To change a name, type over the existing one.

Changes to this field are only saved during a bridge reset, and take effect from then on.

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IP Address / Host Name:

Text Field. The host to which traps pertaining to the community name are to be sent. Specify either an IP address in the dotted decimal notation (nnn.nnn.nnn.nnn), or the name of the host that has been defined in the host table (via the IP Host Table screen).

If you enter a host name defined in the host table, the corresponding IP address is displayed preceding the name. This occurs as soon as you enter or change a community name on some other line on the screen.

If you enter a host name not defined in the host table, an error message is displayed, "Illegal Internet Address".

If you enter an IP address that happens to be defined in the host table (although this is not required), the corresponding host name is displayed (in parenthesis) after the address. This occurs as soon as you enter or change a community name on another line on the screen.

The default is

0.0.0.0

(unknown).

Changes to this field are only saved during a bridge reset, and take effect from then on.

Text Field. The UDP port on the host that is to receive trap

Port:

messages. You usually leave this as the default of

162

, the standard UDP port for SNMP communication. Changes to this field are only saved during a bridge reset, and take effect from then on.

DUA1860-0AAA01

SNMP Configuration 2-53

Enable:

Tex t F ie ld (

/ n). Enter y to enable, or n to disable the Authentication Failure, Cold Start, Interface Up, Interface Down, New Root and Topology Change traps.

An Authentication Failure trap is generated when an SNMP client has tried to access the agent using a community name the agent does not recognize. The Authentication Failure trap must also be enabled on the SNMP Community Basic Configuration screen. If it is not enabled on both screens, no authentication failure traps are generated.

A Cold Start trap is generated when the agent is initializing (or reinitializing) itself and the values of MIB variables may change.

An Interface Up trap is generated when a port that was not operational is now operational.

An Interface Down trap is generated when a port that was operational is no longer operational.

A New Root trap is generated when the bridge on which the agent is running has become the new root of the spanning tree.

A Topology Change trap is generated when one of the configured ports on the bridge has gone into or out of the forwarding state.

Changes to this field are only saved during a bridge reset, and take effect from then on.

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DUA1860-0AAA01

3COM LINKBUILDER MSH 4 PORT ETHERNET BRIDGE MODULE, DUA1860-0AAA01 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

How To Use This Guide

Conventions

Special Messages

Related Publications

The LinkBuilder MSH

The LinkBuilder MSH 4 Port Ethernet Bridge Module

Managing The Bridge

Bridging

Why Use A Bridge?

Local And Remote Bridges

Bridge Network Topology

Learning, Filtering And Forwarding

Spanning Tree Algorithm And Protocol (STAP)

Bridge Filters

What Is Custom Filtering?

Filter Sets

Host-to-Host Filtering

Host-to-Port Filtering

Port-to-Port Filtering

Multicast-to-Port Filtering

Protocol Filtering

Bit Filtering

Enabling Custom Filtering

Simple Network Management Protocol (SNMP)

Installation And Removal

Safety Information

Anti-Static Information

Introduction

The VT100 Management Interface

The VT100 Bridge Screens

The VT100 Bridge Menu Map

Bridge Control Keys

Simple Bridge Configuration

Logging On To The LinkBuilder MSH

Logging On To The Bridge

Establishing Operator Accounts

Adding Bridge Information

Saving And Making Changes Effective

Erasing All Changes

Logging Off The Bridge

IP Address Configuration

Bridge Connections

Logging On To The Bridge

Telnet From The Bridge

Setting Up Remote Access

Active

Next Reset

Static Routes

Assigning Host Name / IP Address Pairs

Using PING To Test Connections

Talking To Another Bridge User

Telnet Suspension

Tel ne t L og Off

SNMP Configuration

Community Administration

Traps

Configuring Basic Community Characteristics

Configuring Community Traps