Cabletron Systems NB20E, NB25 E User Manual

NB20E and NB25 E

TWO PORT ETHERNET BRIDGES

USER’S MANUAL

CABLETRON SYSTEMS, P.O. BOX 6257, ROCHESTER, NH 03867-6257

NOTICE

Cabletron Systems reserves the right to make changes in speciﬁcations and other information contained in this document without prior notice. The reader should in all cases consult Cabletron Systems to determine whether any such changes have been made.

The hardware, ﬁrmware, or software described in this manual is subject to change without notice.

IN NO EVENT SHALL CABLETRON SYSTEMS BE LIABLE FOR ANY INCIDENTAL, INDIRECT, SPECIAL, OR CONSEQUENTIAL DAMAGES WHATSOEVER (INCLUDING BUT NOT LIMITED TO LOST PROFITS) ARISING OUT OF OR RELATED TO THIS MANUAL OR THE INFORMATION CONTAINED IN IT, EVEN IF CABLETRON SYSTEMS HAS BEEN ADVISED OF, KNOWN, OR SHOULD HAVE KNOWN, THE POSSIBILITY OF SUCH DAMAGES.

Cabletron Systems Inc. P.O. Box 6257, E. Rochester, NH 03867-6257

Order Number: 9030040-02 May 90

Remote LANVIEW, LANVIEW, NB25E, NB20E

trademarks of Cabletron Systems Inc.

, and

LAN-MD

are

FCC NOTICE

This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.

WARNING:

This equipment uses and generates and can radiate radio frequency energy and if not installed properly and used in accordance with the instruction manual, may cause interference to radio communications. It has been tested and found to comply with the limits for a Class A digital device pursuant to Subpart J, of Part 15, of the FCC rules., which are designed to provide reasonable protection against such interference in a commercial environment. Operation of this equipment in a residential area is likely to cause interference in which case the user at his own expense will be required to correct the interference.

If this equipment does cause interference to radio or television, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measure:

• Re-orient the receiving antenna.

• Relocate the antenna with respect to the bridge.

• Move the bridge away from the receiver.

• Plug the bridge into a different outlet so that the bridge and the

receiver are on different branch circuits.

If necessary, the user should consult the dealer or an experienced radio/ television technician for additional suggestions. The user may ﬁnd the following booklet prepared by the Federal Communication Commission helpful:

“How to Identify and Resolve Radio TV Interference Problems”

This booklet is available from the U.S. Government Printing Ofﬁce, Washington, D.C. 20401- Stock No. 004-000-00345-4

CHAPTER 1 INTRODUCTION

1.1 USING THIS MANUAL................................................................1-1

1.2 GETTING HELP.......................................................................... 1-2

1.3 THE NB20E AND NB25E TWO PORT ETHERNET BRIDGE ....1-2

1.4 THE BRIDGE FILTERING METHOD.......................................... 1-3

1.5 MULTIPLE BRIDGE ENVIRONMENTS...................................... 1-5

1.5.1 The Root Bridge.............................................................. 1-5

1.5.2 Primary and Redundant Data Paths...............................1-6

1.6 REMOTE LANVIEW....................................................................1-7

1.7 RELATED MANUALS..................................................................1-8

CHAPTER 2 INSTALLATION REQUIREMENTS/

SPECIFICATIONS

2.1 LOCATION REQUIREMENTS.................................................... 2-1

2.2 NETWORK REQUIREMENTS.................................................... 2-1

2.3 OPERATING SPECIFICATIONS ................................................2-2

CHAPTER 3 INSTALLING THE NB20E OR NB25E BRIDGE

3.1 UNPACKING THE NB20E OR NB25E BRIDGE.........................3-1

3.2 INSTALLING THE BRIDGE.........................................................3-1

3.2.1 Installing the Rack Mount Brackets ................................ 3-2

3.2.2 Cable Support Installation............................................... 3-3

3.2.3 Connecting The Bridge To The Network ........................ 3-3

3.2.4 Setting The Mode Switches............................................3-4

3.2.5 Connecting The NB20E or NB25E To

The Power Source.........................................................3-5

CHAPTER 4 TESTING AND LANVIEW

4.1 INSTALLATION CHECK-OUT.....................................................4-1

4.2 USING LANVIEW........................................................................4-2

4.3 USING THE FORWARD BROADCAST SWITCH.......................4-3

4.4 USING THE ROOT SWITCH ......................................................4-4

iii

CONTENTS

CHAPTER 1

INTRODUCTION

Welcome to the Cabletron Systems NB20E™ and NB25E™ Two Port Ethernet Bridges User's Manual. We have designed this user’s manual to serve as a simple installation and reference guide for the NB20E and NB25E, and to explain the capabilities and special features of each individual bridge. With the appropriate design, the Cabletron Systems NB25E or NB20E can dramatically improve network performance and bandwidth efﬁciency on heavily utilized network segments.

You should read through this manual to gain a full understanding of the NB20E and NB25E Bridges and their capabilities.

1.1 USING THIS MANU AL

Chapter 1, NB20E or NB25E Two Port Ethernet Bridge. An explanation of the bridge ﬁltering process and a discussion of bridge functionality in multi-bridge environments are also included. The chapter concludes with a list of related manuals.

Introduction

, discusses the capabilities of Cabletron Systems'

Chapter 2, hardware, software, location and environmental requirements that must be met before you install either bridge.

Chapter 3, instructions for installing the NB20E or the NB25E Two Port Ethernet Bridge.

Chapter 4, and troubleshooting the installation of the NB20E or the NB25E Bridge. Instructions for using LANVIEW™, Cabletron Systems’ built-in visual diagnostic and status monitoring system, are also included.

We assume that you have a general working knowledge of Ethernet or IEEE 802.3 type data communications networks and their physical layer components.

Installation Requirements/Speciﬁcations

Installing the NB20E or NB25E Bridge

Testing and Troubleshooting

, provides procedures for testing

, contains a list of

, contains

1-1

INTRODUCTION

1.2 GETTING HELP

If you need additional support related to the Cabletron Systems NB20E or NB25E Two Port Ethernet Bridge, or if you have any questions, comments or suggestions related to this manual, feel free to contact Cabletron Systems' Technical Support at:

Cabletron Systems Inc. P.O. Box 6257 E. Rochester, NH 03867-6257 Phone: (603) 332-9400

1.3 THE NB20E AND NB25E TWO PORT ETHERNET BRIDGE

With the Cabletron Systems NB20E or NB25E Two Port Ethernet Bridge, you can dramatically increase the performance of two 10 Mbit per second Ethernet networks efﬁciently and economically, regardless of the media type. The bridges are designed to increase the efﬁciency of bandwidth use across a LAN by building a list of local node addresses as it learns which nodes are located on each side of the bridge. This list is called the Source Address Table. The bridge uses the Source Address Table to determine which data packets should be allowed to cross the bridge, keeping local trafﬁc local.

The NB20E Bridge uses a software ﬁlter database to check destination addresses against its Source Address Table. The NB25E Bridge uses a higher performance hardware ﬁlter database. Both bridges are equipped with a feature called Aging Time, that continually makes space for new entries into the Source Address Table by deleting addresses that are not frequently used.

The NB20E and NB25E are designed to function in multiple-bridge environment. As IEEE 802.1 compliant bridging units, the bridges incorporate a Spanning Tree Algorithm to detect potential data loops in the network. Spanning T ree Algorithm is a hierarchy (or tree) of priorities that is established between bridges.

The NB20E and NB25E can be controlled and managed by Cabletron Systems' Remote LANVIEW™ - Network Control Management for the Cabletron Systems' NB20E and NB25E. Remote LANVIEW provides the most complete network management system for Ethernet networks in the industry today. With Remote LANVIEW, a bridge can be managed

1-2

INTRODUCTION

according to the speciﬁc needs of a network manager. The network manager's ability to set up parameters within Remote LANVIEW ensures optimal performance for each bridge, and hence, each network. For example, a network manager can manage and monitor: the ﬂow of trafﬁc through a bridge, the status of a database, the bridge protocol and port parameters, and the bridge setup.

Both bridges also incorporate Cabletron Systems' LANVIEW Status Monitoring and Diagnostics Systems. Should a problem arise, LANVIEW's LEDs will help you to diagnose problems, such as power failures or cable faults. Individual or separate LEDs advise you that: the bridge is on line and operational, the bridge is receiving or transmitting data packets, or the bridge is detecting a collision signal from an individual segment.

The NB20E or NB25E Bridge interconnects networks consisting of Ethernet Version 1, Version 2, and/or IEEE 802.3 equipment. The bridge has two AUI ports so it can be connected directly to any of Cabletron’s many Ethernet transceivers for data transmission over various media including twisted pair, ﬁber optic, and/or thick or thin Ethernet coaxial cable.

1.4 THE BRIDGE FILTERING METHOD

The Cabletron Systems NB20E and NB25E prevent unnecessary network trafﬁc from passing through the bridge, by implementing a ﬁltering process. This process begins with the creation of a list of local node addresses in a table referred to as the Source Address Table.

When the NB20E or NB25E ﬁrst goes on line, the bridge initially forwards all packets through the bridge. As the bridge recei ves a pack et, it learns the address of the sending node from the packet and stores that address in its Source Address Table, indicating the segment on which the address resides. In this manner, the bridge learns the address of each node on each side of the bridge and is able to use the addresses stored in the table to compare the destination address of each subsequent packet that travels to the bridge. If the destination address of a packet is located on the same segment (local segment) as the sending node, the packet is not forwarded across the bridge.

Figure 1-1 provides an illustration of the ﬁltering process.

1-3

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