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3Com LANPLEX 2500 Operation Manual

3Com LANPLEX 2500 Operation Manual

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Part No. 801-00344-000
Published November 1996
Revision 03
LAN
PLEX
O
PERATION
®
2500
G
UIDE

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Summary of Contents for 3Com LANPLEX 2500

  • Page 1 ® 2500 PLEX ® PERATION UIDE Part No. 801-00344-000 Published November 1996 Revision 03...

  • Page 2: Revision

    95052-8145 © 3Com Corporation, 1996. 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.

  • Page 3: Table Of Contents

    ONTENTS BOUT UIDE Introduction 1 How to Use This Guide 1 Conventions 2 LANplex 2500 Documentation 4 Documentation Feedback 5 ANAGEMENT AND DMINISTRATION ® M PLEX ANAGEMENT AND DMINISTRATION VERVIEW About the LANplex® 2500 System 1-1 User Interfaces and the LANplex® 2500 System 1-2 CCESS About the User Interfaces to the LANplex®...
  • Page 4 HYSICAL CCESS ORTS AND ABLING In-band and Out-of-band Management 4-2 Management Access 4-2 Serial Ports 4-2 Ethernet and FDDI Ports 4-3 RIDGING ECHNOLOGY RANSPARENT RIDGING About Transparent Bridging 5-1 What Makes a Bridge 802.1d Compliant? 5-1 How a Bridge Learns Addresses 5-2 How a Bridge Ages Addresses 5-3 Packet Forwarding 5-4 Spanning Tree and the Bridged Network 5-6...
  • Page 5 MACs 9-4 MAC Services 9-4 MAC Operation 9-4 Paths 9-5 Nodes and Attachments 9-5 Nodes 9-5 Attachments 9-6 Node Types 9-6 Station Management 9-8 SMT Operation 9-8 FDDI MIB 9-8 Frame-based Protocols 9-9 FDDI and the LANplex 2500 System 9-10...
  • Page 6 FDDI N ETWORKS About FDDI Networks 10-1 FDDI Network Topologies 10-2 Physical Topology: A Ring of Trees 10-3 Logical Topology: The Dual Ring 10-4 FDDI Connection Rules 10-4 Dual Homing 10-6 ATM T ECHNOLOGY ATM N ETWORKS About ATM 11-1 ATM Basics 11-2 ATM Network Interfaces 11-2 ATM Cell Structure 11-3...
  • Page 7 SNMP MIBs A-1 SNMP MIB Compilers A-4 ECHNICAL UPPORT Online Technical Services B-1 3Com Bulletin Board Service B-1 Access by Analog Modem B-1 Access by Digital Modem B-2 World Wide Web Site B-2 3ComForum on CompuServe® Online Service B-2 3ComFactsSM Automated Fax Service B-3...

  • Page 8: About This Guide

    BOUT UIDE Introduction This LANplex® 2500 Operation Guide provides all the information you need to understand how your LANplex® switching hub works in FDDI, Ethernet, and ATM networking environments. This guide is intended for the system or network administrator who is Audience responsible for configuring, using, and managing the LANplex®...

  • Page 9: Conventions

    If you are looking for information on... Turn to... Asynchronous Transfer Mode (ATM) technology Chapter 11 SNMP MIB support Appendix A 3Com Technical Support Appendix B Definitions for operating the system Glossary Conventions Table 2 and Table 3 list conventions that are used throughout this guide.
  • Page 10 Conventions Table 3 Text Conventions Convention Description “Enter” vs. “Type” The word “enter” means type something, and then press the Return or Enter key. Do not press the Return or Enter key when an instruction simply says “type.” “Syntax” vs. “Command” The word “syntax”...

  • Page 11: Lanplex 2500 Documentation

    BOUT UIDE LANplex 2500 The following documents comprise the LANplex 2500 documentation set. Documentation If you want to order additional documents or one that you do not have, contact your sales representative for assistance. LANplex® 2500/2016 Unpacking Instructions Describes how to unpack your LANplex system. It also provides you with an inventory list of all the items shipped with your system.

  • Page 12: Documentation Feedback

    Your suggestions are very important to us. To help make the documentation Feedback more useful to you, please send comments about this document in e-mail to 3Com at: sdtechpubs_comments@3Mail.3Com.com Please include the following information when commenting: Document title Document part number (listed on the back cover and the title page) Page number (if appropriate) LANplex®...

  • Page 13: Anagement And Administration

    ANAGEMENT AND DMINISTRATION Chapter 1 Management and Administration Overview Chapter 2 User Access: What You See Chapter 3 Management Access: Protocols Chapter 4 Physical Access: Ports and Cabling...

  • Page 15: Lan Plex

    VERVIEW This chapter introduces you to how your LANplex® system is managed and administered. About the The LANplex 2500 system combines high port density, Ethernet switching, LANplex® 2500 Ethernet-to-FDDI bridging, Fast Ethernet switching, FDDI switching, and System ATM switching in an integrated system. You can configure much of this functionality to meet your specific networking needs.

  • Page 16: User Interfaces And The Lanplex® 2500 System

    1: LAN ® M HAPTER PLEX ANAGEMENT AND DMINISTRATION VERVIEW Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data-Link Layer (Logical Link Control) — IEEE 802.2 Physical Layer FDDI Figure 1-1 OSI Reference Model Using the LANplex system’s own management application or an external SNMP- based management application, the system can be managed and administered through various protocols and physical interfaces.
  • Page 17 User Interfaces and the LANplex® 2500 System LANplex 2500 system ® Discussed in Chapter 2: User Access: What Administration SNMP Administration You See Managers Console Console Application Application Layer Discussed in Chapter 3: Management Access: telnet, Terminal telnet, SNMP SNMP Protocols rlogin, ftp Emulation...
  • Page 18 1: LAN ® M HAPTER PLEX ANAGEMENT AND DMINISTRATION VERVIEW...

  • Page 19: User Access : What You See

    CCESS This chapter describes the applications you can use to gain access to your LANplex system and to perform administrative and management functions. About the User You can use the following applications as the user interface to your LANplex Interfaces to the system: LANplex®...
  • Page 20 2: U HAPTER CCESS LANplex 2500 system ® Administration SNMP Administration Managers Console Console Application Application Layer telnet, Terminal telnet, SNMP SNMP rlogin, ftp Emulation rlogin, ftp Agent SNMP/SMT Proxy Agent Transport Layer Network Layer Data-link & Physical Layers FDDI FDDI Ethernet Ethernet...

  • Page 21: The Built-In Lanplex® Administration Console

    The Built-in LANplex® Administration Console The Built-in You can use the Administration Console to configure your LANplex system LANplex® to operate effectively in your networking environment. You can also use the Administration Administration Console to display network statistics. Console You can view the Administration Console from a terminal, a workstation, a Macintosh, or a PC.

  • Page 22: External Network Management Applications

    3Com products, including the LANplex 2500 system. With Transcend Enterprise Manager software, you get a device view of the LANplex 2500 so you can display the operating status, configure, and get statistics about each device.
  • Page 23 External Network Management Applications Groups and individual devices Devices in the selected group Figure 2-4 Sample Screen from Transcend® Enterprise Manager Status View Software Because the LANplex system is based on SNMP standards, you can manage your system using third-party SNMP-based network manager applications, ™...

  • Page 24: Management Access : Protocols

    This chapter describes the underlying communication and management protocols used to deliver management and administration data to and from your LANplex system. About LANplex® The LANplex 2500 system uses the following protocols: 2500 Protocols Virtual terminal protocols, such as rlogin and telnet Simple Network Management Protocol (SNMP)
  • Page 25 3: M HAPTER ANAGEMENT CCESS ROTOCOLS LANplex 2500 system ® Administration SNMP Administration Console Application Managers Console Application Layer telnet, Terminal telnet, SNMP SNMP rlogin, ftp Emulation rlogin, ftp Agent SNMP/SMT Proxy Agent Transport Layer Network Layer Data-link & Physical Layers FDDI Ethernet Ethernet...

  • Page 26: Virtual Terminal Protocols

    Virtual Terminal Protocols Virtual Terminal A virtual terminal protocol is a software program, such as rlogin or telnet, Protocols that allows you to establish a management session from a PC or a UNIX workstation. Because rlogin and telnet run over TCP/IP, you must have at least one IP address configured on the LANplex system before you can establish access to it with a virtual terminal protocol.

  • Page 27: Snmp

    3: M HAPTER ANAGEMENT CCESS ROTOCOLS SNMP Simple Network Management Protocol (SNMP) is the standard management protocol for multivendor IP networks. SNMP supports transaction-based queries that allow the protocol to format messages and to transmit information between reporting devices and data-collection programs. It runs on top of the User Datagram Protocol (UDP), offering a connectionless-mode service.

  • Page 28: Snmp Traps

    Through SNMP and your network management software or through the Administration Console, you can configure which traps are sent to which IP addresses. Table 3-1 lists the SNMP traps supported by the LANplex system. Table 3-1 SNMP Traps in the LANplex 2500 system Group Trap MIB II...

  • Page 29: Access Control

    3: M HAPTER ANAGEMENT CCESS ROTOCOLS Access Control Access to system information through SNMP is controlled by community strings. A community string is a character string included in each SNMP protocol message sent between your LANplex system and external management applications like Transcend Enterprise Manager. A community string identifies a particular group of SNMP managers with certain access rights.

  • Page 30: Snmp And Smt Proxy Agents

    SNMP and SMT Proxy Agents SNMP and SMT A proxy agent acts as a management gateway. It converts requests and Proxy Agents event reports from one protocol and object format to another protocol and object format. Your LANplex system contains a proxy agent that translates between SNMP and FDDI SMT.
  • Page 31 HYSICAL CCESS ORTS AND ABLING This chapter explains how you can manage your LANplex system through its physical interfaces. Figure 4-1 highlights the system’s physical access options in the OSI reference Model environment. LANplex 2500 system ® SNMP Administration Administration Managers Console Console Application...

  • Page 32: Serial Ports

    LANs for management data, then you are managing your network out-of-band. For more information on system management, see the LANplex 2500 Administration Console User Guide. Management You can access the LANplex system through 1) a serial port or 2) any Access Ethernet or FDDI port.

  • Page 33: Ethernet And Fddi Ports

    Management Access Modem port Terminal port LANplex 2500 system ® Either connection Modem Terminal Terminal Workstation Figure 4-2 Access Through the Console Port Ethernet and Using the rlogin or telnet interfaces, you can access the Administration FDDI Ports Console through any Ethernet or FDDI port if an IP address is assigned to the ports.
  • Page 34 4: P HAPTER HYSICAL CCESS ORTS AND ABLING Figure 4-3 shows management access through any Ethernet or FDDI port. LANplex 2500 system ® FDDI port Ethernet port Workstation Workstation Figure 4-3 Access to the LANplex System Through any Ethernet or FDDI Port...

  • Page 35: Bridging Technology

    RIDGING ECHNOLOGY Chapter 5 Transparent Bridging Chapter 6 Express Switching Chapter 7 User-defined Packet Filtering Chapter 8 Bridging Extensions...

  • Page 36: About Transparent Bridging

    Age addresses of stations on attached LANs that have not transmitted a packet for a prolonged period of time Store and forward packets from one LAN to another Use the Spanning Tree Protocol for loop detection The LANplex 2500 system complies with all IEEE 802.1d bridging requirements.

  • Page 37: How A Bridge Learns Addresses

    5: T HAPTER RANSPARENT RIDGING How a Bridge Bridges learn addresses so that they can make intelligent decisions about Learns Addresses which packets to forward from one bridge port to another. A bridge automatically learns addresses by listening on the network. For a bridge to learn the address of a station on the network, that station must transmit a packet.

  • Page 38: How A Bridge Ages Addresses

    Address aging is also necessary because a bridge can learn only a finite number of addresses. The LANplex 2500 system, when configured as an IEEE 802.1d bridge, can learn up to 8K addresses in its address table.

  • Page 39: Packet Forwarding

    5: T HAPTER RANSPARENT RIDGING Packet A bridge either filters, floods, or forwards packets by comparing the packet’s Forwarding destination address to the addresses in the bridge’s address table, and by comparing the destination bridge port (if known) to the port on which the packet was received.

  • Page 40: Packet Forwarding

    Packet Forwarding Forwarding 1 Packet enters bridge Bridge 2 Packet’s destination address is compared to bridge’s address table 3 Address is known and destination port is different from source Address Table 4 Packet is forwarded to the destination port Transmitting station Receiving station Filtering 1 Filtered packet enters bridge...

  • Page 41: Spanning Tree And The Bridged Network

    5: T HAPTER RANSPARENT RIDGING Spanning Tree When transparent bridges are used to attach networks with redundant links, and the Bridged packets can loop and rapidly multiply on the attached LANs. These Network additional packets create traffic that might unnecessarily clog the LAN. A loop exists if more than one path can be used to forward a packet from one station to another.

  • Page 42: The Spanning Tree Algorithm

    Spanning Tree and the Bridged Network Transmitting station LAN 1 Bridge A Bridge B Bridge C LAN 2 Figure 5-3 Packets Looping and Multiplying Without Spanning Tree Protocol The Spanning Tree The Spanning Tree algorithm detects loops and logically blocks (eliminates) Algorithm redundant paths by putting some bridge ports in the blocking state so that only one path exists between any two LANs and, therefore, between any...

  • Page 43: How The Spanning Tree Algorithm Works

    5: T HAPTER RANSPARENT RIDGING Transmitting station LAN 1 Bridge A Bridge B Bridge C BLOCKED BLOCKED LAN 2 Figure 5-4 Spanning Tree Protocol Implemented to Block Redundant Links How the Spanning Tree Algorithm Works The Spanning Tree algorithm is based on the idea that bridges transmit messages to each other that allow them to calculate the Spanning Tree topology.
  • Page 44 Spanning Tree and the Bridged Network receiving information. Figure 5-5 shows the hierarchy of the Spanning Tree bridges and their ports. Root Bridge Designated port Root port Designated Bridge Designated port Root port Bridge Figure 5-5 Hierarchy of the Root Bridge and the Designated Bridge From the information that the CBPDUs provide, the bridges: Elect a single bridge to be the root bridge.
  • Page 45 5-10 5: T HAPTER RANSPARENT RIDGING Figure 5-6 shows a bridged network with its Spanning Tree elements. Designated port Designated Bridge bridge for LAN 3 LAN 3 Root Root port LAN 1 Designated ports Bridge Designated bridge for LANs Root bridge 1, 2, and 4 LAN 4 LAN 2...
  • Page 46 Spanning Tree and the Bridged Network 5-11 the transmitting bridge ID. If the CBPDUs all have the same root ID, cost, and transmitting bridge ID, then the port identifier is used as a tiebreaker. Example 1. Message 1 has a lower root ID, so the bridge saves the message.

  • Page 47: How Spanning Tree Is Calculated For The Network

    5-12 5: T HAPTER RANSPARENT RIDGING This CBPDU looks like this: 85.0.85. 2 The bridge receives CBPDUs on each of its ports from all other bridges. It saves the “best” CBPDU from each port. The best one is determined by comparing the information in each message arriving at a particular port to the message the bridge currently has stored at that port.
  • Page 48 Spanning Tree and the Bridged Network 5-13 LAN 1 CBPDU (root ID.cost.transmitter ID) 12.0.12 10.0.10 Bridge A Bridge B LAN 5 LAN 2 35.0.35 Bridge E 20.0.20 Bridge C Bridge D 29.0.29 LAN 6 LAN 3 81.0.81 Bridge F LAN 4 Figure 5-7 Starting the Spanning Tree Calculation The root ID portion of the CBPDU determines which bridge will be the root bridge.
  • Page 49 5-14 5: T HAPTER RANSPARENT RIDGING LAN 1 Root CBPDU Bridge (root ID.cost.transmitter ID) 10.11.12 10.0.10 Bridge A Bridge B LAN 5 LAN 2 Bridge E 10.11.35 10.11.20 Bridge C 10.11.29 Bridge D LAN 6 LAN 3 10.12.81 Bridge F (R) = Root Port (D) = Designated Port (B) = Backup Port...
  • Page 50 Spanning Tree and the Bridged Network 5-15 If the bridge has more than one port attachment, the port with the lowest cost becomes the root port, and the other ports become either designated or backup ports. If bridges have redundant links to the same LAN, then the port with the lowest port identifier becomes the root port.

  • Page 51: Spanning Tree Port States

    5-16 5: T HAPTER RANSPARENT RIDGING Spanning Tree As the Spanning Tree algorithm determines the Spanning Tree configura- Port States tion, it places ports in the following states: listening, learning, forwarding, blocking, or disabled. As changes occur in the network, the port may transi- tion in and out of these states to maintain a loopless network.
  • Page 52 Spanning Tree and the Bridged Network 5-17 Table 5-1 Spanning Tree Port States (continued) Port State Description Disabled A port is disabled when Spanning Tree Protocol has been turned off for that specific port or when the port has failed. In the disabled state, the port does not participate in the Spanning Tree algorithm.

  • Page 53: Reconfiguring The Bridged Network Topology

    5-18 5: T HAPTER RANSPARENT RIDGING Reconfiguring the The Spanning Tree algorithm reconfigures the bridged network topology Bridged Network when 1) bridges are added or removed, 2) the root bridge fails, or 3) the Topology network administrator changes the bridging parameters that determine the topology.

  • Page 54: Express Switching

    Address learning and aging Packet filtering and forwarding Advantages and constraints About Express The LANplex 2500 system supports a mode of bridging called Express Switching Switching. This mode is slightly different from the transparent bridging described in Chapter 5: Transparent Bridging.
  • Page 55 6: E HAPTER XPRESS WITCHING Server LANplex ® 2500 system Workstations Figure 6-1 Express Switching — Flat Topology Traditional transparent bridging is preferable in environments that contain tree or mesh topologies that mix extended Ethernet and FDDI networks. See Figure 6-2. LANplex ®...

  • Page 56: Address Learning

    Address Learning Address Learning In Express Switching mode, the LANplex 2500 system learns the source addresses only of stations not connected to the bridge’s backbone port. The bridge listens to the frames transmitted by stations and stores their addresses in a table. The address table is referenced by the filtering/ forwarding function of the bridge.
  • Page 57 6: E HAPTER XPRESS WITCHING Using Express Switching mode in your network has these contraints: Directed (unicast) packets are not forwarded to an end-station that is not connected to the backbone until the bridge has learned that station’s address. Therefore, in certain circumstances, a station must “speak before it can be spoken to.”...

  • Page 58: User - Defined Packet Filtering

    DEFINED ACKET ILTERING The LANplex system allows you to add a second layer of packet filtering on top of the standard filtering provided by a traditional transparent bridge. This chapter contains the following information on user-defined packet filters: A general description How to use address groups and port groups in packet filters Some packet filters How to administer user-designed packet filters...

  • Page 59: Assigning Packet Filters To Paths

    7: U HAPTER DEFINED ACKET ILTERING Table 7-1 Some Simple Packet Filter Operands Operand Description Constant A literal value. A constant can be 1, 2, 4, or 6 bytes. Packet field A field in the packet that can reside at any offset. The size of the field can be 1, 2, 4, or 6 bytes.

  • Page 60: Packet Filter Examples

    About User-defined Packet Filtering Placing a filter on the receive path prohibits a packet from accessing certain network segments unless it meets the forwarding criteria. A packet is discarded if it does not meet the forwarding criteria defined in the filter. See Figure 7-1Figure 7-1. Receive Transmit path...

  • Page 61: Example 1: Isolating Ip Segments

    7: U HAPTER DEFINED ACKET ILTERING Example 1: Isolating IP Segments The network shown in Figure 7-2 is composed of two types of protocols: The Internet protocol (IP), over which Sun® workstations and a compute server communicate AppleTalk® Phase I protocol, over which Apple® Macintosh workstations and servers communicate FDDI ports LANplex...
  • Page 62 About User-defined Packet Filtering Solution: To isolate the IP segments, define a packet filter that discards all AppleTalk packets received on the transmit path of ports that have only IP stations connected to them. (All ports would need a packet filter if the filter were installed on the receive path.) The filter definition is: If type field = AppleTalk then discard packet...

  • Page 63: Example 2: Filtering Appletalk Phase Ii Packets

    7: U HAPTER DEFINED ACKET ILTERING Example 2: Filtering AppleTalk Phase II Packets If your Macintosh computers use the AppleTalk Phase II protocol instead of the AppleTalk Phase I protocol (as shown in Example 1), then you must use a filter slightly more complicated. AppleTalk Phase II uses 802.3 protocol instead of Ethernet as the physical layer protocol.
  • Page 64 About User-defined Packet Filtering In this example, several simple expressions are combined to form the complete complex logical expression. Expressions can be differentiated as follows: Expression 1: type field <= 1500 Operand 1 is the type field, which is a 2-byte value at offset 12 in the AppleTalk Phase II packet.

  • Page 65: Using Address Groups And Port Groups In A Packet Filter

    An address group is a list of MAC addresses. You can configure up to 32 Group? address groups per LANplex 2500 system. You can associate the same address group with multiple systems. When an address is added to a group, the address is inserted into the address table on each system that is associated with that group.

  • Page 66: What Is A Port Group

    Port groups are conceptually similar to address groups. A port group is a list Group? of ports. Because the LANplex 2500 system has only 2 bridge ports (16 Ethernet ports and 2 FDDI), a group can have no more than 18 ports. You can configure up to 32 port groups per LANplex 2500 system.
  • Page 67 7-10 7: U HAPTER DEFINED ACKET ILTERING groups. When the port is added to a group, the corresponding bit in the mask is set. See Figure 7-7 Port Table Port Group Mask FDDI port 1 0f400000 00000000 Ethernet port 1 Ethernet port 2 00000658 Ethernet port 3...

  • Page 68: Referencing Address Groups And Port Groups From A Packet Filter

    Using Address Groups and Port Groups in a Packet Filter 7-11 Referencing After you configure address and port groups, you can refer to them in a Address Groups packet filter. The packet filter language defines several operands that relate and Port Groups to address and port groups.
  • Page 69 7-12 7: U HAPTER DEFINED ACKET ILTERING LANplex 6012 system ® Compute server B Compute server A LANplex 6012 system ® FDDI ports LANplex 2500 system B ® FDDI ports FDDI backbone LANplex 2500 system A ® Bridge relay Bridge relay Ethernet ports Ethernet ports...
  • Page 70 Using Address Groups and Port Groups in a Packet Filter 7-13 To implement packet filtering in the designed scheme for this network, take these steps: 1 Set up address groups as follows: Address group 1 — Accounting 00-01-02-03-04-03 00-01-02-03-04-0a 00-01-02-03-04-04 00-01-02-03-04-0b 00-01-02-03-04-05 00-01-02-03-04-0c...
  • Page 71 HAPTER DEFINED ACKET ILTERING table in Figure 7-9 on page 7-75 is for LANplex 2500 system Engineering Group A. 2 After setting up the address groups, generate the following filter: if (source address group mask AND destination address group mask) = 0 then discard packet The expressions used in this example filter can be separated as follows:...
  • Page 72 Using Address Groups and Port Groups in a Packet Filter 7-15 Address Table Address Port Group Mask 00010203040e Ethernet Port 3 00000001 000102030403 Ethernet Port 1 00000001 000102030421 FDDI Port 1 00000004 00010203040c Ethernet Port 3 00000001 This station, on Ethernet port 8, is 000102030411 included in the Engineering A Ethernet Port 8...

  • Page 73: Globally Administering Packet Filters

    7-16 7: U HAPTER DEFINED ACKET ILTERING LANplex 6012 system ® Compute server B Compute server A LANplex 6012 system ® FDDI ports LANplex 2500 system B ® FDDI ports FDDI backbone LANplex 2500 system A ® Bridge relay Packet filters on receive path Bridge Ethernet ports...

  • Page 74: Lan Plex ® Bridging Extensions

    ® PLEX RIDGING XTENSIONS This chapter describes LANplex® 2500 bridging extensions, a functionality that enhances bridge performance. These extensions include: Multicast packet firewalls IP fragmentation Reduced packet flooding Network security enhancements Multicast Packet A network error condition that can significantly disrupt communication to Firewalls attached stations is a multicast storm.

  • Page 75: Ip Fragmentation

    8: LAN ® B HAPTER PLEX RIDGING XTENSIONS Figure 8-1 illustrates the threshold mechanism for the multicast packet firewall. For information on setting this threshold, see the LANplex® 2500 Administration Console User Guide. Multicast/ Receive broadcast rate storm 400 Packets/second Threshold Firewall Time...

  • Page 76: Reducing Packet Flooding

    This causes increased packet flooding. The LANplex 2500 system supports the traditional aging mechanism, but it also contains logic that monitors the source address in every packet, ensuring that the port associated with that address has not changed.

  • Page 77: Enhanced Network Security

    Enhanced In addition to allowing you to design and use packet filters to improve Network Security network security (as described in Chapter 7), the LANplex 2500 system allows you to use statically configured addresses as a form of network security.
  • Page 78 FDDI T ECHNOLOGY Chapter 9 FDDI Overview and Implementation Chapter 10 FDDI Networks...

  • Page 79: Fddi Overview And Implementation

    FDDI O VERVIEW AND MPLEMENTATION This chapter discusses FDDI concepts and terms. The final section shows how FDDI is implemented in the LANplex® 2500 system. About FDDI Fiber Distributed Data Interface (FDDI) is a standards-based solution that provides fast and reliable data transfer on a local area network (LAN). FDDI’s sophisticated technology, which supports data transfer of 100 million bits per second (100 Mbps), was developed by the American National Standards Institute (ANSI).
  • Page 80 9: FDDI O HAPTER VERVIEW AND MPLEMENTATION The industry guideline for FDDI technology is divided into four major standards: Physical Medium Dependent (PMD) — PMD specifies the characteristics of the fiber optic medium, the connectors that attach stations to the fiber optic medium, the transmission wavelength, the power requirements for transmitters, and the methods for optically bypassing inactive stations.

  • Page 81: Ports

    Ports Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data-Link Layer (Logical Link Control) — IEEE 802.2 Physical Layer FDDI Figure 9-1 FDDI Relationship to OSI Reference Model Ports As parts of the Physical Layer, the PHY and PMD entities work together to support each link between FDDI stations.

  • Page 82: Macs

    9: FDDI O HAPTER VERVIEW AND MPLEMENTATION Each port is one of four types: A, B, M, and S. A port — Connects to the primary ring on the incoming fiber and the secondary ring on the outgoing fiber. A properly formed FDDI dual ring is composed of a set of stations with the A port of one station connected to the B port of the neighboring station.

  • Page 83: Paths

    Paths Paths FDDI’s dual, counter-rotating ring is made up of a primary and secondary ring. FDDI stations can be connected to either ring or to both rings simultaneously. Data flows downstream on the primary ring in one direction from one station to its neighboring station. The secondary ring serves as a redundant path and flows in the opposite direction.

  • Page 84: Attachments

    9: FDDI O HAPTER VERVIEW AND MPLEMENTATION PHY/PMD entities (M ports) are used for connecting other FDDI stations, including other concentrators, in a tree topology. Attachments Attachments refer to how a node, station, or concentrator is connected to an FDDI network. They are classified as single attachment and dual attachment.
  • Page 85 Nodes and Attachments SM-DAS FDDI Duplex dual fiber ding cable DM-DAS = A port = B port = Master port = Slave port Figure 9-2 Examples of FDDI Configurations...

  • Page 86: Station Management

    9: FDDI O HAPTER VERVIEW AND MPLEMENTATION Station Each FDDI station has one Station Management (SMT) entity to provide Management connection management, ring management, and operational management to the FDDI network. SMT specifies a set of services and signaling mechanisms dedicated to FDDI network management. It manages those services of each station on the FDDI network that are specific to the Physical Layer and the MAC portion of the Data Link Layer.

  • Page 87: Frame-Based Protocols

    Station Management Frame-based SMT provides a number of frame-based services that are used by higher Protocols level management functions into manage stations on the network and to gather information about them. Frame-based protocols: Gather network statistics Detect, isolate, and resolve faults in the network Tune FDDI configuration and operational parameters to meet application and connectivity requirements SMT has six key frame-based protocols:...

  • Page 88: Fddi And The Lanplex 2500 System

    9-10 9: FDDI O HAPTER VERVIEW AND MPLEMENTATION FDDI and the Your LANplex 2500 system combines into one system the power of LANplex 2500 FDDI and: System Ethernet switching Ethernet-to-FDDI transparent bridging FDDI switching Fast Ethernet switching ATM switching. This combination dramatically enhances LAN performance and increases the capacity of your existing Ethernet network.
  • Page 89 2500 system SAS server (FDDI link) Duplex LANplex ® fiber 2500 system cable DAS server LANplex LANplex ® ® 2500 system 6000 or 2500 (DAS) system NETBuilder II ® router Figure 9-3 Sample FDDI Configuration for the LANplex 2500 system...

  • Page 90: Fddi Networks

    FDDI N ETWORKS This chapter provides general information about FDDI networks and describes the differences between physical and logical topologies. Also covered: FDDI connection rules and dual homing. About FDDI FDDI networks have important differences from other types of LANs. FDDI Networks networks can provide a network backbone between buildings on a campus or within a multilevel high-rise building.

  • Page 91: Fddi Network Topologies

    10-2 10: FDDI N HAPTER ETWORKS FDDI Network The term network topology refers to the ways that stations are Topologies interconnected within a network. An FDDI network topology may be viewed at two distinct levels: Physical topology — A network’s physical topology is defined by the arrangement and interconnection of its nodes.

  • Page 92: Physical Topology: A Ring Of Trees

    FDDI Network Topologies 10-3 Physical Topology: The FDDI trunk ring consists of dual-attach stations (DASs) and dual-attach A Ring of Trees connectors (DACs). The DACs on the ring allow you to attach trees. The trees consist of branches of single-attach stations (SASs) and DASs that are star-wired off the concentrators.

  • Page 93: Logical Topology: The Dual Ring

    10-4 10: FDDI N HAPTER ETWORKS This means that subsets of legal topologies are also legal. Examples of legal FDDI topologies include the dual ring with trees, the dual ring without trees, and the single tree. For information on legal topologies, see the section “FDDI Connection Rules”...
  • Page 94 FDDI Connection Rules 10-5 rejected. The FDDI SMT standard cites detailed connection rules for a specific port (“this Port”) to other ports, which are shown in Table 10-1. Table 10-1 Port Connection Rules Port Connection Connection Rules A to A Undesirable peer connection that creates twisted primary and secondary rings;...

  • Page 95: Dual Homing

    10-6 10: FDDI N HAPTER ETWORKS Table 10-2 provides a connection rule matrix summarizing the validity of most types of connections. Table 10-2 Connection Rule Matrix Other Port A V, U V, U This Port V, U V, U S V, U V, U I, U V —...
  • Page 96 Dual Homing 10-7 Secondary system Link set by configuration policy FDDI Duplex Dual-homed dual fiber node ring cable Primary link Primary system Figure 10-4 Dual Homing For additional information about dual homing, see the LANplex® 2500 Getting Started guide.
  • Page 97 ATM T ECHNOLOGY Chapter 11 ATM Networks...

  • Page 98: Atm Networks

    ATM N ETWORKS This chapter provides general information about: The basic concepts of ATM and its architecture How ATM handles addressing, signaling and virtual connections Traffic management on the ATM network The basic concepts of LAN emulation (LANE) ATM and the LANplex system About ATM In 1986, the Comité...

  • Page 99: Atm Basics

    11-2 11: ATM N HAPTER ETWORKS short, repetitive needs of voice transmission. ATM thus allows a free mixture of data and voice or video within the same application. Scalable technology — ATM accommodates a wide range of transmission rates and applications. Seamless connectivity —...

  • Page 100: Atm Cell Structure

    About ATM 11-3 Figure 11-1 shows ATM network UNIs and NNIs. Private switch Public switch Private switch Public switch Public switch Private switch Public switch Private UNI Public UNI Private NNI Public NNI Figure 11-1 ATM Network UNIs and NNIs ATM Cell Structure One of the challenges in defining ATM was to determine a structure that could efficiently handle any type of traffic.
  • Page 101 11-4 11: ATM N HAPTER ETWORKS User Data GFC — Generic Flow Control (on U VPI — Virtual Path Identifier VCI — Virtual Channel Identifier PTI — Payload Type Identifier CLP — Cell Loss Priority HEC — Header Error Control Figure 11-2 UNI ATM Cell Structure These fields make up an ATM cell: Generic Flow Control (GFC)—...

  • Page 102: Virtual Connections In Atm

    About ATM 11-5 Virtual Connections ATM switching is performed at the ATM layer by defining virtual in ATM connections. Virtual connections are communication channels that provide for sequential, unidirectional transport of ATM cells. Multiple virtual connections can exist on a physical link. A connection is identified by a circuit identifier, called a virtual channel identifier (VCI), to exchange data between two ATM stations over a previously established virtual channel connection (VCC).

  • Page 103: Permanent Virtual Circuits

    11-6 11: ATM N HAPTER ETWORKS Permanent Virtual Circuits PVCs are established via network management and are left up indefinitely. Both point-to-point and point-to-multipoint connections can be estab- lished. Virtual Paths and As in traditional LAN packets, the header of each ATM cell contains Virtual Channels addressing information.

  • Page 104: Atm Protocol Architecture

    ATM Protocol Architecture 11-7 end-station end- station Application Application Data Data switch switch Layers Layers VPI/VCI VPI/VCI Table Table VPI/VCI VPI/VCI Table Table Virtual Path Virtual Path Virtual Path Virtual Channel Virtual Channel Virtual Channel Virtual Channel Connection Figure 11-4 Virtual Connections ATM Protocol ATM layers do not map directly to the Open Systems Interconnect (OSI) Architecture...

  • Page 105: The Physical Layer

    11-8 11: ATM N HAPTER ETWORKS The primary layers of the BISDN reference model are: The Physical Layer The ATM Layer The ATM adaptation Layer The Physical Layer The Physical Layer defines how cells are transported over the network. This are of influence includes physical interfaces, media, and information rates.

  • Page 106: The Atm Adaptation Layer (Aal)

    ATM Protocol Architecture 11-9 The ATM Adaptation The ATM adaptation Layer (AAL) provides the user-oriented functions that Layer (AAL) are not included as part of the ATM Layer. These user-oriented functions allow the ATM Layer to support the transport of different types of higher layer protocols and services.

  • Page 107: Interim Local Management Interface (Ilmi) Communication Protocol

    11-10 11: ATM N HAPTER ETWORKS receiving data, the SAR reassembles the contents of the ATM cell information fields into the higher-layer protocol data units. Interim Local The ILMI communication protocol is an open management protocol that Management supports the bi-directional exchange of management information between Interface (ILMI) all end-stations and the switches to which they are connected.

  • Page 108: Integrating Atm In Legacy Lans

    Integrating ATM in Legacy LANs 11-11 Address registration is performed in two phases: 1 The network side supplies the network portion of the address (network prefix). 2 The user side appends the end-system identifier (ESI) of the address and registers the complete address with the network side. Either side can dynamically register and de-register their respective parts of the address.

  • Page 109: Lan Emulation (Lane)

    11-12 11: ATM N HAPTER ETWORKS Figure 11-7 shows how ATM operates in a LAN network. Routing Layer 3 Classical IP Bridging over ATM Layer 2 LANE AAL5 Ethernet FDDI Layer 1 Figure 11-7 ATM in a LAN network LAN Emulation LAN Emulation (LANE) enables existing applications to access an ATM (LANE) network via protocol stacks as if they were operating over traditional LANs.
  • Page 110 LAN Emulation (LANE) 11-13 IEEE 802.2 LLC Emulation Sublayer ATM Adaptation Layer ATM Layer Physical Layer Figure 11-8 LAN Emulation Sublayer In a traditional IEEE 802.x LAN, traffic is transmitted to all stations on the shared physical medium, with each station determining which packets it should receive and which packets should be discarded.

  • Page 111: Lane Components

    11-14 11: ATM N HAPTER ETWORKS A B C Router Figure 11-9 ATM Network Using LAN Emulation Three important concepts are illustrated in Figure 11-9: Network nodes may be members of the same LAN emulation service (ATM LAN segment) even if they are connected to different switches in the network, as long as the switches are interconnected.

  • Page 112: Virtual Channel Connections (Vcc)

    LAN Emulation (LANE) 11-15 LAN Emulation Client (LEC) — A set of functions implemented in an ATM endpoint which serves as an interface between it and the ATM network in support of LAN Emulation. LAN Emulation Server (LES) — The set of functions implemented in the ATM network support of LAN Emulation.

  • Page 113: Atm And The Lanplex System

    2500 Administration Console User Guide. LAN Emulation You can use LAN Emulation (LANE) in the LANplex 2500 system to provide unicast, multicast, and broadcast network behavior over connection- oriented ATM. LANE allows you to group physical segments into a common broadcast domain called an emulated LAN (ELAN).

  • Page 114: Creating An Emulated Lan

    ATM and the LANplex System 11-17 VLANs, see Chapter 2: VLANs in the LANplex System in the LANplex 2500 Extended Switching User Guide. Creating an Emulated LAN You can create an 802.3 emulated LAN on ATM by defining the LAN’s servers (the BUS and the LES) and then configuring each LAN Emulated...
  • Page 115 Engineering Engineering Marketing Figure 11-10 Multiple ELANs Configured on LANplex 2500 Systems In this example, two bridge ports are connected to the same location, causing a bridge loop. A similar example would be the connection of two LANplex 2500 systems by means of two Ethernet segments.
  • Page 116 PPENDIXES Appendix A SNMP MIB Support Appendix B Technical Support...
  • Page 117 SNMP MIB S UPPORT This appendix lists the SNMP MIBs supported by the LANplex system software and describes the supported SNMP compilers. SNMP MIBs SNMP MIB files are shipped with the LANplex system software as ASN.1 files. The currently supported version of each MIB is listed in this section. All applicable MIB attributes are supported unless otherwise specified.
  • Page 118 A: SNMP MIB S PPENDIX UPPORT — Bridge MIB, RFC 1493 bridge.mib The following Bridge MIB attributes are not supported: dot1dBase Group dot1dBasePortDelayExceedDiscards dot1dSr Group dot1dTp Group dot1dFdbTable dot1dStatic Group — Ethernet MIB, RFC 1398 ethernet.mib The following Ethernet MIB attributes are not supported: dot3StatsTable dot3StatsMultipleCollisionFrames dot3StatsSQETestErrors...
  • Page 119 SNMP MIBs les.mib — ATM MIB, af-lane-1129.001 The following LES MIB attributes are not supported: lesconfGroup lesAtmAddrSpec lesAtmAddrMask lesStatGroup lesLecStatGroup lesFaultGroup — LANplex Systems MIB, version 1.3.0 lp.mib The following LANplex Systems MIB trap is not supported: lpsSystemFanFailure — LANplex Optional FDDI MIB, version 1.2.1, based on SMT 7.3 lpOpFddi.mib The following LANplex Optional FDDI MIB attributes are not supported: lpOptMAC Group...

  • Page 120: Snmp Mib Compilers

    A: SNMP MIB S PPENDIX UPPORT SNMP MIB ASN.1 MIB files are provided for each of the MIB compilers listed in this Compilers section. Any warnings or exceptions related to a compiler are listed with it. SMIC (version 1.0.9) MOSY (version 7.1) For the MIB file lpOpFddi.mib, the MOSY compiler reports warnings for counter names that do not end in “s”...

  • Page 121: Online Technical Services

    3Com provides easy access to technical support information through a variety of services. This appendix describes these services. Online Technical 3Com offers worldwide product support 24 hours a day, seven days a week, Services through the following online systems: 3Com Bulletin Board Service (3ComBBS) World Wide Web site 3ComForum on CompuServe®...

  • Page 122: Access By Digital Modem

    (3Com’s award-winning technical journal) and more. 3ComForum on 3ComForum, based on CompuServe Online Service, contains patches, CompuServe® software, drivers, and technical articles about all 3Com products, as well as a Online Service messaging section for peer support. To use 3ComForum, you need a CompuServe account.

  • Page 123: Support From Your Network Supplier

    Support from If additional assistance is required, contact your network supplier. Many Your Network suppliers are authorized 3Com service partners who are qualified to provide Supplier a variety of services, including network planning, installation, hardware maintenance, application training, and support services.

  • Page 124: Support From 3Com

    3Com. In the U.S. and Canada, call (800) 876-3266 for customer service. If you are outside the U.S. and Canada, contact your local 3Com sales office to find your authorized service provider. Use one of these numbers:...
  • Page 125 PERATION LOSSARY A port In FDDI technology, each DAS contains two ports: A and B. The A port is connected to the primary ring on the incoming fiber and the secondary ring on the outgoing fiber. A properly formed trunk ring is composed of a set of stations with the A port of one station connected to the B port of the neighboring station.
  • Page 126 Examples: a bridge that connects an Ethernet network to an FDDI network allows the two networks to send signals to each other. The LANplex 2500 Ethernet/FDDI Switching Module (EFSM) can operate as a translation/transparent 802.1d bridge.
  • Page 127 PERATION LOSSARY cell An ATM Layer protocol data-unit (PDU), characterized by fixed-length rather than variable-length payloads. The standard ATM cell is 48 bytes of payload with 5 bytes of header. cell relay See ATM. client A single-user computer that requests application or network services from a server.
  • Page 128 PERATION LOSSARY Dual attachment station. A station directly attached to FDDI’s dual token rings. A DAS has four fiber attachments consisting of one receive and one transmit fiber for each ring. Rather than an individual user workstation, a DAS is most likely to be the device controlling LAN operation, such as an FDDI concentrator, bridge, router, server, minicomputer, or mainframe.
  • Page 129 PERATION LOSSARY backup ring is used for automatic recovery in case of failure. If a network fault occurs, only the stations on either side of the fault are affected. They detect the fault and automatically bypass it to maintain continuous transmission of data.
  • Page 130 PERATION LOSSARY ILMI Interim Local Management Interface. ATM Forum-defined interim specifications for network management functions between a piece of ATM data terminal equipment (DTE) and an ATM switch over the user-to-network interface (UNI). Based on a limited subset of SNMP capabilities. in-band Network management performed using the same network normally used management...
  • Page 131 PERATION LOSSARY LAN Emulation Server. The LES implements the control coordination function for the Emulated LAN. It also provides a facility for registering and resolving MAC addresses and route descriptors to ATM addresses. Logical link control. The upper sublayer of the data link layer of the OSI seven-layer reference model.
  • Page 132 PERATION LOSSARY nonvolatile memory Computer memory that is preserved when power is lost. Also called NVRAM. Operation and maintenance cell. This cell contains ATM maintenance and performance monitoring information. It does not form part of the upper- layer information transfer. operating system A program that manages and provides access to system resources.
  • Page 133 PERATION LOSSARY primary path See FDDI paths. primary ring One of two counter-rotating, fiber optic rings that serve as the root of an FDDI network. The primary ring normally enters each station on the trunk ring through the A port and exits through the B port. See also secondary ring.
  • Page 134 PERATION LOSSARY the other) form used on data transmissions links. This port can be used for dedicated local management access. S port Slave port. Each PHY/PMD pair, designated a port, belongs to one of four types: A, B, M, or S. A single attachment station (SAS or SAC) has an S port intended to be attached to an M port within a concentrator tree.
  • Page 135 PERATION LOSSARY station An addressable logical and physical attachment in a ring that is capable of transmitting, receiving, and repeating information. An FDDI station has one or more PHY entities, one or more MAC entities, and only one SMT entity. station ID The unique identifier for an FDDI station or concentrator.
  • Page 136 5-8 least cost path 5-9 root 5-8 Bridge Protocol Data Unit (BPDU) 5-18 Numerics bridging 3Com Bulletin Board Service (3ComBBS) B-1 configuration messages 5-8 3Com sales offices B-4 extensions 8-1 to 8-4 3ComFacts B-3 IEEE 802.1d compliant 5-1 3ComForum B-2...
  • Page 137 NDEX DAS 9-10 generic flow control 11-4 designated bridge 5-8 groups, address. See address group designated port 5-8, 5-9 groups, port. See port group disabled port state 5-17 dual homing 10-6 dual ring, FDDI 10-4 dual-attachment stations 9-10 header error control 11-4 HEC 11-4 emulated LAN (ELAN) creating 11-16...
  • Page 138 NDEX managing LANplex forwarding 5-4, 6-2 from outside the network 2-4 fragmentation 8-2 protocols 3-1 to 3-4 looping 5-6 managing LANplex systems reduced flooding 8-3 protocols 3-1 to 3-4 packet filter Master port 9-4 address groups 7-8, 7-11 MIB 3-5 and an AppleTalk network 7-4 events 3-5 and Express switching 6-3...
  • Page 139 NDEX topology, FDDI 10-2 to 10-4 Transcend® Enterprise Manager SNMP community strings, and 3-6 receive path 7-1 Transcend® Enterprise Manager software 3-4 returning products for repair B-4 transmit path 7-1 ring of trees 10-3 transparent bridging rlogin 3-3 aging addresses, and 5-3 root bridge 5-8 defined 5-1 root port 5-8...

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