3com SuperStack 3 Uživatelský manuál

http://www.3com.com/Part No. DUA1730-0BAA01Published April 2002SuperStack® 3Switch Implementation GuideGeneric guide for units in the SuperStack 3 Swi

10ABOUT THIS GUIDEPlease include the following information when contacting us: Document title Document part number (on the title page) Page number (if

100GLOSSARY

INDEXNumbers802.1Dpriority levels 48traffic classification 48802.1Q tagging 64Aaddressesclasses 87IP 85aggregated links 14, 22example 25aging time, de

102INDEXIGMP multicast filtering 30Internetaddresses 85InterNIC 86IP (Internet Protocol)addresses 86IP address 14, 70, 85classes of 87defined 86deriva

INDEX103Root Port 37using on a network with multiple VLANs 42subnet mask 88defined 88example 88numbering 89subnets 88subnetworkingdefined 88subnet mas

ISWITCH FEATURESChapter 1 Switch Features OverviewChapter 2Optimizing BandwidthChapter 3Using Multicast FilteringChapter 4Using Resilience FeaturesCha

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1SWITCH FEATURES OVERVIEWThis chapter contains introductory information about the SuperStack®3 Switch management software and supported features. It c

14CHAPTER 1: SWITCH FEATURES OVERVIEWAutomatic IPConfigurationBy default the Switch tries to configure itself with IP information without requesting u

Switch Features Explained15For details of the auto-negotiation features supported by your Switch, please refer to the Getting Started Guide that accom

16CHAPTER 1: SWITCH FEATURES OVERVIEWSpanning TreeProtocol and RapidSpanning TreeProtocolSpanning Tree Protocol (STP) and Rapid Spanning Tree Protocol

Switch Features Explained17This system is compatible with the relevant sections of the IEEE 802.1D/D17 standard (incorporating IEEE 802.1p).For more i

18CHAPTER 1: SWITCH FEATURES OVERVIEWVLANsA Virtual LAN (VLAN) is a flexible group of devices that can be located anywhere in a network, but which com

2OPTIMIZING BANDWIDTHThere are many ways you can optimize the bandwidth on your network and improve network performance. If you utilize certain Switch

3Com Corporation5400 Bayfront Plaza Santa Clara, California 95052-8145Copyright © 2002, 3Com Technologies. All rights reserved. No part of this docume

20CHAPTER 2: OPTIMIZING BANDWIDTHIf the devices at either end of a link do not support auto-negotiation, both ends must be manually set to full duplex

Port Features21port and react accordingly. In other words, auto-negotiation may “agree” upon a configuration that the cable cannot sustain; smart auto

22CHAPTER 2: OPTIMIZING BANDWIDTHAggregated LinksAggregated links are connections that allow devices to communicate using up to two links in parallel.

Aggregated Links23 If ports of a different speed are aggregated together, the higher speed links carry the traffic. The lower speed links only carry t

24CHAPTER 2: OPTIMIZING BANDWIDTHTraffic Distribution and Link Failure on Aggregated LinksTo maximize throughput, all traffic is distributed across th

Aggregated Links25Aggregated LinkExampleThe example shown in Figure 3 illustrates an 2 Gbps aggregated link between two Switch units.Figure 3 A 2 Gb

26CHAPTER 2: OPTIMIZING BANDWIDTH

3USING MULTICAST FILTERINGMulticast filtering improves the performance of networks that carry multicast traffic.This chapter explains multicasts, mult

28CHAPTER 3: USING MULTICAST FILTERINGA multicast packet is identified by the presence of a multicast group address in the destination address field o

Multicast Filtering29Figure 4 The effect of multicast filteringMulticast Filteringand Your SwitchYour Switch provides automatic multicast filtering

CONTENTSABOUT THIS GUIDEConventions 8Related Documentation 9Documentation Comments 9Product Registration 101SWITCH FEATURES OVERVIEWWhat is Management

30CHAPTER 3: USING MULTICAST FILTERINGcommand will configure the Switch 4200 Series to automatically negotiate with compatible devices on VLAN 1 to be

IGMP Multicast Filtering31If IGMP multicast learning is not enabled then IP multicast traffic is always forwarded, that is, it floods the network.For

32CHAPTER 3: USING MULTICAST FILTERING

4USING RESILIENCE FEATURESSetting up resilience on your network helps protect critical links against failure, protects against network loops, and redu

34CHAPTER 4: USING RESILIENCE FEATURESRapid Spanning TreeProtocol (RSTP)The Rapid Spanning Tree (RSTP) is an enhanced Spanning Tree feature. RSTP impl

What is STP?35Figure 5 A network configuration that creates loopsFigure 6 shows the result of enabling STP on the bridges in the configuration. STP

36CHAPTER 4: USING RESILIENCE FEATURESFigure 7 Traffic flowing through Bridge BSTP determines which is the most efficient path between each bridged

How STP Works37cost, the less efficient the link. Table 3 shows the default port costs for a Switch. Ta bl e 3 Default port costs STP CalculationThe

38CHAPTER 4: USING RESILIENCE FEATURESSTP ConfigurationAfter all the bridges on the network have agreed on the identity of the Root Bridge, and have e

How STP Works39Figure 8 Port costs in a network Bridge A has the lowest Bridge Identifier in the network, and has therefore been selected as the Roo

3USING MULTICAST FILTERINGWhat is an IP Multicast? 27Benefits of Multicast 28Multicast Filtering 28Multicast Filtering and Your Switch 29IGMP Multicas

40CHAPTER 4: USING RESILIENCE FEATURES Bridge C has been selected as the Designated Bridge for LAN segment 3, because it offers the lowest Root Path C

How STP Works41Figure 9 STP configurations

42CHAPTER 4: USING RESILIENCE FEATURESDefault BehaviorThis section contains important information to note when using the RSTP and Fast Start features,

Using STP on a Network with Multiple VLANs43Figure 10 Configuration that separates VLANsTo avoid any VLAN subdivision, it is recommended that all in

44CHAPTER 4: USING RESILIENCE FEATURES

5USING THE SWITCH DATABASEWhat is the Switch Database?The Switch Database is used by the Switch to determine where a packet should be forwarded to, an

46CHAPTER 5: USING THE SWITCH DATABASESwitch Database Entry StatesDatabases entries can have three states: Learned — The Switch has placed the entry i

6USING TRAFFIC PRIORITIZATIONUsing the traffic prioritization capabilities of your Switch allows your network traffic to be prioritized to ensure that

48CHAPTER 6: USING TRAFFIC PRIORITIZATION Resource planning applications — Used by organizations that require predictable and reliable access to enter

How Traffic Prioritization Works49You cannot alter the mapping of the priorities. These are fixed to the traffic types as shown in Figure 11.Figure 11

7STATUS MONITORING AND STATISTICSRMON 53What is RMON? 53The RMON Groups 54Benefits of RMON 54RMON and the Switch 55Alarm Events 56The Default Alarm Se

50CHAPTER 6: USING TRAFFIC PRIORITIZATIONFigure 12 DSCP Service Level MappingFigure 12 illustrates how DiffServ code point (DSCP) service levels are

Traffic Prioritization and your Switch51How traffic is processed to provide Quality of ServiceA received packet at the ingress port is checked for its

52CHAPTER 6: USING TRAFFIC PRIORITIZATIONsomewhere else in the network and not in the Switch 4200. Note also that 802.1D service levels are fixed and

7STATUS MONITORING AND STATISTICSThis chapter contains details of the features that assist you with status monitoring and statistics.For detailed desc

54CHAPTER 7: STATUS MONITORING AND STATISTICSthe same network as the Switch and can manage the Switch by in-band or out-of-band connections.The RMON G

RMON and the Switch55addition, probes record the behavior of your network, so that you can analyze the causes of problems. It reduces the load on the

56CHAPTER 7: STATUS MONITORING AND STATISTICSAlarm EventsYou can define up to 200 alarms for the Switch. The events that you can define for each alarm

RMON and the Switch57The Audit LogThe Switch keeps an audit log of all management user sessions, providing a record of a variety of changes, including

58CHAPTER 7: STATUS MONITORING AND STATISTICSYou can configure the email address to which you wish the notifications to be sent. However, you cannot c

Hardware Status Monitoring59Figure 13 Example CLI screen textFigure 14 Example of an individual unit system summary screen Via the web.On the Web

Configuration Rules with Full Duplex 77BNETWORK CONFIGURATION EXAMPLESSimple Network Configuration Examples 80Segmentation Switch Example 80Collapsed

60CHAPTER 7: STATUS MONITORING AND STATISTICSFigure 15 Example device summary web page RMON TrapSee “Events” on page 54 for details of this feature

8SETTING UP VIRTUAL LANSSetting up Virtual LANs (VLANs) on your Switch reduces the time and effort required by many network administration tasks, and

62CHAPTER 8: SETTING UP VIRTUAL LANSFigure 16 A network setup showing three VLANsBenefits of VLANsThe main benefit of VLANs is that they provide a n

VLANs and Your Switch63 VLANs help to control trafficWith traditional networks, congestion can be caused by broadcast traffic that is directed to all

64CHAPTER 8: SETTING UP VIRTUAL LANSVLANs: Tagged andUntaggedMembershipYour Switch supports 802.1Q VLAN tagging, a system that allows traffic for mult

VLANs and Your Switch65Connecting VLANS toOther VLANSIf the devices placed in a VLAN need to communicate to devices in a different LAN, each VLAN requ

66CHAPTER 8: SETTING UP VIRTUAL LANSVLAN Configuration ExamplesThis section contains examples of simple VLAN configurations. It describes how to set u

VLAN Configuration Examples672 Add ports to the VLANsAdd ports 10, 11 and 12 of the Switch as untagged members to VLAN 2.Using 802.1Q TaggedConnection

68CHAPTER 8: SETTING UP VIRTUAL LANS3 Add port 12 on Switch 1 to the VLANsAdd port 12 on Switch 1 as a tagged member of both VLANs 1 and 2 so that all

9USING AUTOMATIC IP CONFIGURATIONThis chapter explains more about IP addresses and how the automatic configuration option works. It covers the followi

ABOUT THIS GUIDEThis guide describes the features of the SuperStack®3 Switch 4200 Series and outlines how to use these features to optimize the perfor

70CHAPTER 9: USING AUTOMATIC IP CONFIGURATIONHow Your Switch Obtains IP Information You can use one of the following methods to allocate IP informatio

How Automatic IP Configuration Works71Automatic ProcessTo detect its IP information using the automatic configuration process, the Switch goes through

72CHAPTER 9: USING AUTOMATIC IP CONFIGURATIONImportant ConsiderationsThis section contains some important points to note when using the automatic IP c

IIAPPENDICES AND INDEXAppendix A Configuration RulesAppendix BNetwork Configuration ExamplesAppendix CIP AddressingGlossaryIndex

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ACONFIGURATION RULESConfiguration Rules for Gigabit EthernetGigabit Ethernet is designed to run over several media: Single-mode fiber optic cable, wit

76APPENDIX A: CONFIGURATION RULESConfiguration Rules for Fast EthernetThe topology rules for 100 Mbps Fast Ethernet are slightly different to those fo

Configuration Rules for Fast Ethernet77collapsed backbone). For example, a 225 m (738 ft) fiber link from a repeater to a router or switch, plus a 100

78APPENDIX A: CONFIGURATION RULES

BNETWORK CONFIGURATION EXAMPLESThis chapter contains the following sections: Simple Network Configuration Examples Segmentation Switch Example Collaps

8ABOUT THIS GUIDEConventionsTa bl e 1 and Tabl e 2 list conventions that are used throughout this guide.Ta bl e 1 Notice IconsIcon Notice Type Desc

80APPENDIX B: NETWORK CONFIGURATION EXAMPLESSimple Network Configuration ExamplesThe following illustrations show some simple examples of how the Swit

Simple Network Configuration Examples81Collapsed BackboneSwitch ExampleThe example in Figure 22 shows how a Switch 4200 stack can act as a backbone fo

82APPENDIX B: NETWORK CONFIGURATION EXAMPLESDesktop SwitchExampleThe example in Figure 23 shows how a Switch 4200 can be used for a group of users tha

Advanced Network Configuration Examples83Advanced Network Configuration ExamplesThis section shows some network examples that illustrate how you can s

84APPENDIX B: NETWORK CONFIGURATION EXAMPLESEnhancing thePerformance of YourNetworkFigure 25 shows how you can set your network up to enhance its perf

CIP ADDRESSINGThis chapter provides some background detail on the IP information that needs to be assigned to your Switch to enable you to manage it a

86APPENDIX C: IP ADDRESSING192.168.100.X (where X is a number between 1 and 254) with a subnet mask 255.255.255.0. If you are using SLIP, use the defa

IP Addresses87Dotted Decimal NotationThe actual IP address is a 32-bit number that is stored in binary format. These 32 bits are segmented into 4 grou

88APPENDIX C: IP ADDRESSINGSubnets and Subnet MasksYou can divide your IP network into sub-networks also known as subnets. Support for subnets is impo

Subnets and Subnet Masks89As shown in this example, the 32 bits of an IP address and subnet mask are usually written using an integer shorthand. This

Related Documentation9Related DocumentationIn addition to this guide, each Switch documentation set includes the following: Getting Started GuideThis

90APPENDIX C: IP ADDRESSINGThe subnet mask 255.255.255.255 is reserved as the default broadcast address.Default GatewaysA gateway is a device on your

GLOSSARY3Com NetworkSupervisorThe 3Com network management application used to manage 3Com’s networking solutions.10BASE-TThe IEEE specification for 10

92GLOSSARYFast Ethernet is 100 Mbps, and the bandwidth of Gigabit Ethernet is 1000 Mbps.baudThe signalling rate of a line, that is, the number of tran

93DHCPDynamic Host Control Protocol. A protocol that lets you centrally manage and automate the assignment of Internet Protocol (IP) addresses in an o

94GLOSSARYgatewaySee router.GBICGigabit Interface Converter.Gigabit EthernetIEEE standard 802.3z for 1000 Mbps Ethernet; it is compatible with existin

95Internet GroupManagementProtocolInternet Group Management Protocol (IGMP) is a protocol that runs between hosts and their immediate neighboring mult

96GLOSSARYloopAn event that occurs when two network devices are connected by more than one path, thereby causing packets to repeatedly cycle around th

97POSTPower On Self Test. An internal test that a Switch carries out when it is powered-up.QoS ProfileConsists of multiple sets of rules (classifier p

98GLOSSARYstandard service levels, for example, best effort, business critical, network control, and so on.SLIPSerial Line Internet Protocol. A protoc

99TCP relates to the content of the data travelling through a network — ensuring that the information sent arrives in one piece when it reaches its de