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3Com 3CR17501-91 - SuperStack 3 Switch 3250 Implementation Manual
Summary of 3CR17501-91 - SuperStack 3 Switch 3250
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Http://www.3com.Com/ part no. Dua1750-0baa01 published december 2003 superstack ® 3 switch 3226 and switch 3250 implementation guide 3cr17500-91 3cr17501-91.
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3com corporation 350 campus drive marlborough, ma usa 01752-3064 copyright © 2003, 3com corporation. 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 writt...
Page 3: Ontents
C ontents a bout t his g uide conventions 10 related documentation 11 documentation comments 11 1 s witch f eatures o verview what is management software? 13 switch features explained 13 aggregated links 14 auto-negotiation 14 configuration save and restore 15 multicast filtering 16 rapid spanning t...
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Implementing 802.3ad aggregated links 25 aggregated links and your switch 25 aggregated link — manual configuration example 27 3 u sing m ulticast f iltering what is an ip multicast? 29 benefits of multicast 30 multicast filtering 30 multicast filtering and your switch 31 igmp multicast filtering 31...
Page 5: Lan
802.1d traffic classification 48 diffserv traffic classification 49 ip port traffic classification 50 traffic prioritization and your switch 51 limiting the rate of a port 52 traffic prioritization and rate limiting 53 7 s tatus m onitoring and s tatistics rmon 55 what is rmon? 55 the rmon groups 55...
Page 6: Ip R
10 m aking y our n etwork s ecure limiting management access by ip address 71 securing access to the web interface 72 getting a digital certificate 72 securing access to the command line interface 73 access control lists 73 how access control list rules work 74 port security 74 what is network login...
Page 7: Ip A
A c onfiguration r ules configuration rules for gigabit ethernet 99 configuration rules for fast ethernet 100 configuration rules with full duplex 101 b n etwork c onfiguration e xamples simple network configuration example 104 desktop switch example 104 advanced network configuration example 105 ed...
Page 9: Bout
A bout t his g uide this guide describes the features of the 3com ® superstack ® 3 switch 3226 (3cr17500-91) and 3com ® superstack ® 3 switch 3250 (3cr17501-91). It outlines how to use these features to optimize the performance of your network. The terms switch 3226 and switch 3250 are used when ref...
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10 a bout t his g uide conventions table 1 and table 2 list conventions that are used throughout this guide. Table 1 notice icons icon notice type description information note information that describes important features or instructions caution information that alerts you to potential loss of data ...
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Related documentation 11 related documentation in addition to this guide, each switch documentation set includes the following: ■ superstack 3 switch 3226 and superstack 3 switch 3250 getting started guide this guide contains: ■ all the information you need to install and set up the switch in its de...
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12 a bout t his g uide please include the following information when contacting us: ■ document title ■ document part number (on the title page) ■ page number (if appropriate) example: ■ superstack ® 3 switch 3226 and switch 3250 implementation guide ■ part number: dua1750-0baa01 ■ page 25 please not...
Page 13: Witch
1 s witch f eatures o verview this chapter contains introductory information about the switch management software and supported features. It covers the following topics: ■ what is management software? ■ switch features explained for detailed descriptions of the web interface operations and the comma...
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14 c hapter 1: s witch f eatures o verview aggregated links aggregated links are connections that allow devices to communicate using multiple links in parallel. Your switch supports one aggregated link using the two 10/100/1000 and sfp ports (25-26 on the switch 3225, 49-50 on the switch 3250). Aggr...
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Switch features explained 15 flow control uses backjamming on ports operating in half duplex mode, and is implemented using the ieee std 802.3-2002 (incorporating 802.3x) on ports operating in full duplex mode. For more information about auto-negotiation and port capabilities, see chapter 2 “optimiz...
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16 c hapter 1: s witch f eatures o verview ■ lacp automatic aggregations — that is, lacp enabled on all ports and the aggregated links created automatically. The aggregated link should be enabled and spanning tree protocol enabled. Parameters such as vlans and fast start may be set up as required. F...
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Switch features explained 17 ■ enable one of the less efficient paths if the most efficient path fails. Rstp is an enhanced version of stp (spanning tree protocol) and is fully compatible with stp systems. Rstp can restore a network connection quicker than the legacy stp feature. Rstp can detect if ...
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18 c hapter 1: s witch f eatures o verview management application, the switch can transfer these statistics to your workstation on request or when a pre-defined threshold is exceeded. For more information about rmon and event notification, see chapter 7 “status monitoring and statistics” . Broadcast...
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Switch features explained 19 all currently learnt addresses on the port are made permanent. Any packets containing a source address not learnt on the port will be dropped. ■ network login connections are only allowed on a port once the client has been authenticated by a radius server. For more infor...
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20 c hapter 1: s witch f eatures o verview.
Page 21: Ptimizing
2 o ptimizing b andwidth there are many ways you can optimize the bandwidth on your network and improve network performance. If you utilize certain switch features you can provide the following benefits to your network and end users: ■ increased bandwidth ■ quicker connections ■ faster transfer of d...
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22 c hapter 2: o ptimizing b andwidth a link do not support auto-negotiation, both ends must be manually set to full duplex or half duplex accordingly. Ports operating at 1000 mbps support full duplex mode only. Flow control all switch ports support flow control, which is a mechanism that prevents p...
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Aggregated links 23 aggregated links aggregated links are connections that allow devices to communicate using multiple member links in parallel. Aggregated links provide the following benefits: ■ they can potentially increase the bandwidth of a connection. The capacity of the multiple links is combi...
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24 c hapter 2: o ptimizing b andwidth by default, lacp is disabled on all switch ports. If a member link in an aggregated link fails, the traffic using that link is dynamically reassigned to the remaining member links in the aggregated link. Figure 2 shows the simplest case: two member links, that i...
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Aggregated links 25 implementing 802.3ad aggregated links lacp can be enabled or disabled on a per port basis. You can implement 802.3ad aggregated links in two ways: ■ manual aggregations — you can manually add and remove ports to and from an aggregated link via web commands. However, if a port has...
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26 c hapter 2: o ptimizing b andwidth ■ a member link port can only belong to one aggregated link. ■ the member link ports can be mixed media, that is fiber and/or twisted pair ports within the same aggregated link. ■ the member link ports must have the same configuration. When using an aggregated l...
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Aggregated links 27 aggregated link traffic to the remaining ports. Aggregated links therefore provide built-in resilience for your network. The switch also has a mechanism to prevent the possible occurrence of packet re-ordering when a link recovers too soon after a failure. Aggregated link — manua...
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28 c hapter 2: o ptimizing b andwidth 3 connect port 5 on the core switch to port 25 on the switch 3226. 4 connect port 7 on the upper switch to port 26 on the switch 3226..
Page 29: Sing
3 u sing m ulticast f iltering multicast filtering improves the performance of networks that carry multicast traffic. This chapter explains multicasts, multicast filtering, and how multicast filtering can be implemented on your switch. It covers the following topics: ■ what is an ip multicast? ■ mul...
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30 c hapter 3: u sing m ulticast f iltering a multicast packet is identified by the presence of a multicast group address in the destination address field of the packet’s ip header. Benefits of multicast the benefits of using ip multicast are that it: ■ enables the simultaneous delivery of informati...
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Multicast filtering and your switch 31 figure 4 the effect of multicast filtering multicast filtering and your switch your switch provides automatic multicast filtering support using igmp (internet group management protocol) snooping. It also supports igmp query mode. Snooping mode snooping mode all...
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32 c hapter 3: u sing m ulticast f iltering igmp multicast filtering works as follows: 1 the ip router (or querier) periodically sends query packets to all the endstations in the lans or vlans that are connected to it. If your network has more than one ip router, then the one with the lowest ip addr...
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Multicast filtering and your switch 33 wish to join or to which they already belong. The querier is always the device with the lowest ip address in the subnetwork. It can be a router or a layer 2 switch. The network traffic flows most efficiently if the querier is the closest device to the sources o...
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34 c hapter 3: u sing m ulticast f iltering routers on the subnetwork. Upon receiving such a message, the querier determines whether that host is the last group member on the subnetwork by issuing a group-specific query. Leave-group messages reduce leave latency — that is, the time between when the ...
Page 35: Sing
4 u sing r esilience f eatures setting up resilience on your network helps protect critical links against failure, protects against network loops, and reduces network downtime to a minimum. The switch provides resilient links using the rapid spanning tree protocol (rstp). The protocol configures its...
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36 c hapter 4: u sing r esilience f eatures the protocol is a part of the ieee std 802.1w-2001, bridge specification. To explain rstp more effectively, your switch will be referred to as a bridge. Rapid spanning tree protocol (rstp) the rapid spanning tree (rstp) is an enhanced spanning tree feature...
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What is stp? 37 as an example, figure 5 shows a network containing three lan segments separated by three bridges. With this configuration, each segment can communicate with the others using two paths. Without stp enabled, this configuration creates loops that cause the network to overload. Figure 5 ...
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38 c hapter 4: u sing r esilience f eatures if a link failure is detected, as shown in figure 7 , the stp process reconfigures the network so that traffic from lan segment 2 flows through bridge b. Figure 7 traffic flowing through bridge b stp determines which is the most efficient path between each...
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How stp works 39 ■ each port to have a cost. This specifies the efficiency of each link, usually determined by the bandwidth of the link — the higher the cost, the less efficient the link. Table 3 shows the default port costs for a switch. Table 3 default port costs stp calculation the first stage i...
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40 c hapter 4: u sing r esilience f eatures bridge is configured to forward traffic only between its root port and the designated bridge ports for the respective network segments. All other ports are blocked, which means that they are prevented from receiving or forwarding traffic. Stp reconfigurati...
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How stp works 41 figure 8 port costs in a network ■ bridge a has the lowest bridge identifier in the network, and has therefore been selected as the root bridge. ■ because bridge a is the root bridge, it is also the designated bridge for lan segment 1. Port 1 on bridge a is therefore selected as the...
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42 c hapter 4: u sing r esilience f eatures ■ the route through bridges c and b costs 200 (c to b=100, b to a=100) ■ the route through bridges y and b costs 300 (y to b=200, b to a=100). Port 2 on bridge c is therefore selected as the designated bridge port for lan segment 3. Stp configurations figu...
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How stp works 43 figure 9 stp configurations.
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44 c hapter 4: u sing r esilience f eatures using stp on a network with multiple vlans the ieee std 802.1d, 1998 edition does not take into account vlans when it calculates stp information — the calculations are only performed on the basis of physical connections. For this reason, some network confi...
Page 45: Sing
5 u sing the s witch d atabase what is the switch database? The switch database is used by the switch to determine where a packet should be forwarded to, and which port should transmit the packet if it is to be forwarded. The database contains a list of entries — each entry contains three items: ■ m...
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46 c hapter 5: u sing the s witch d atabase switch database entry states databases entries can have three states: ■ learned — the switch has placed the entry into the switch database when a packet was received from an endstation. Note that: ■ learned entries are removed (aged out) from the switch da...
Page 47: Sing
6 u sing t raffic m anagement using the traffic management capabilities of your switch allows your network traffic to be controlled and prioritized to ensure that high priority data is transmitted with minimum delay. The switch 3226 and switch 3250 have two features that allow you to manage the traf...
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48 c hapter 6: u sing t raffic m anagement ■ financial applications — used by accounts departments that need immediate access to large files and spreadsheets. ■ cad/cam design applications — used by design departments that need priority connections to server farms and other devices for transferring ...
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How traffic prioritization works 49 the 802.1d standard specifies eight distinct levels of priority (0 to 7), each of which relates to a particular type of traffic. The priority levels and their traffic types are shown in figure 11 in order of increasing priority. You cannot alter the mapping of pri...
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50 c hapter 6: u sing t raffic m anagement figure 12 dscp service level mapping figure 12 illustrates how diffserv code point (dscp) service levels are mapped to the four traffic queues. Ip port traffic classification the switch supports classification of traffic from legacy devices by classifying t...
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Traffic prioritization and your switch 51 figure 13 ip port mapping figure 13 illustrates how ip port numbers are mapped to the four traffic queues. Traffic prioritization and your switch your switch sorts traffic based on class of service. It does not mark or remark a packet with a tag, but priorit...
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52 c hapter 6: u sing t raffic m anagement 802.1d packets are categorized into the eight traffic classes defined by ieee 802.1d; the higher the class the higher the priority given to the packet on transmission. See figure 11 . Dscp packets are categorized into the six service levels as shown in figu...
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Limiting the rate of a port 53 configuring rate limiting rate limiting can be configured on your switch using the web interface or the command line interface (cli). Rate limiting can be applied in steps of 1 mb on 10/100 ports and in steps of 8 mb on 10/100/1000 ports. For a detailed description of ...
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54 c hapter 6: u sing t raffic m anagement.
Page 55: Tatus
7 s tatus m onitoring and s tatistics this chapter contains details of the remote monitoring ( rmon ) feature that assists you with status monitoring and statistics. For detailed descriptions of the web interface operations and the command line interface (cli) commands that you require to manage the...
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56 c hapter 7: s tatus m onitoring and s tatistics statistics the statistics group provides traffic and error statistics showing packets, bytes, broadcasts, multicasts and errors on a lan segment or vlan. Information from the statistics group is used to detect changes in traffic and error patterns i...
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Benefits of rmon 57 benefits of rmon using the rmon features of your switch has three main advantages: ■ it improves your efficiency using rmon allows you to remain at one workstation and collect information from widely dispersed lan segments or vlans. This means that the time taken to reach a probl...
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58 c hapter 7: s tatus m onitoring and s tatistics when using the rmon features of the switch, note the following: ■ after the default sessions are created, they have no special status. You can delete or change them as required. ■ the greater the number of rmon sessions, the greater the burden on th...
Page 59: Etting
8 s etting u p v irtual lan s setting up virtual lans (vlans) on your switch increases the efficiency of your network by dividing the lan into logical, rather than physical, segments which are easier to manage. This chapter explains more about the concept of vlans and explains how they can be implem...
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60 c hapter 8: s etting u p v irtual lan s figure 14 a network setup showing three vlans benefits of vlans the main benefit of vlans is that they provide a network segmentation system that is far more flexible than any traditional network. Using vlans also provides you with three other benefits: ■ v...
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Vlans and your switch 61 ■ vlans help to control traffic with traditional networks, congestion can be caused by broadcast traffic that is directed to all network devices whether they require it or not. Vlans increase the efficiency of your network because each vlan can be set up to contain only thos...
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62 c hapter 8: s etting u p v irtual lan s figure 15 shows a how a layer 3 switch can be used to route between vlans on the switch and how an additional vlan can be used to aggregate two vlans. Figure 15 two vlans connected to a core switch using a third vlan the switch can also be used to route tra...
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Vlans and your switch 63 figure 16 two vlans connected via a layer 3 switch creating new vlans if you want to move a port from the default vlan to another vlan, you must first define information about the new vlan on your switch. Vlans: tagged and untagged membership your switch supports 802.1q vlan...
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64 c hapter 8: s etting u p v irtual lan s to carry multiple vlans across a single physical (backbone) link, each packet must be tagged with a vlan identifier so that the switches can identify which packets belong in which vlans. To communicate between vlans a router must be used. Vlan configuration...
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Vlan configuration examples 65 to set up the configuration shown in figure 17 : 1 configure the vlans define vlan 2 on the switch. Vlan 1 is the default vlan and already exists. 2 add ports to the vlans add ports 10, 11 and 12 of the switch as untagged members to vlan 2. You can use the switch web i...
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66 c hapter 8: s etting u p v irtual lan s.
Page 67: Sing
9 u sing a utomatic ip c onfiguration this chapter explains more about ip addresses and how the automatic configuration option works. It covers the following topics: ■ how your switch obtains ip information ■ how automatic ip configuration works ■ important considerations for detailed information on...
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68 c hapter 9: u sing a utomatic ip c onfiguration how automatic ip configuration works when your switch is powered up for the first time the ip configuration setting is set to auto — this is the default setting. If your switch has been powered up before, whichever of the three options for ip config...
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Important considerations 69 if you want dhcp to be the method for automatic configuration, make sure that your dhcp servers are operating normally before you power on your switch..
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70 c hapter 9: u sing a utomatic ip c onfiguration.
Page 71: Aking
10 m aking y our n etwork s ecure this chapter outlines the port security and switch management login features, explains the key benefits of using these features, and gives examples of how and why you would use them in your network. For detailed descriptions of the web interface operations and the c...
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72 c hapter 10: m aking y our n etwork s ecure interface of the switch using console port, even if you have denied all access to the switch using the trusted ip feature. Securing access to the web interface the switch 3226 and switch 3250 support https, allowing secure access to the web interface of...
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Securing access to the command line interface 73 has not been certified by a certificate authority (ca) but security will not be otherwise affected. If you cannot generate an x.509 certificate yourself, you can buy one from one of the certifying authorities or your isp. Each switch requires its own ...
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74 c hapter 10: m aking y our n etwork s ecure a maximum of 32 access lists can be applied under the current operating system. Access list rules can be applied and traffic is forwarded at wire speed using layer 3 destination ip addresses and network ports. How access control list rules work when a p...
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What is network login? 75 the port. The source mac address in received packets is used to determine this; all traffic from other network devices is filtered. What is network login? Network login controls user access at the network edge by blocking or unblocking access on a per-port basis. When a cli...
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76 c hapter 10: m aking y our n etwork s ecure switch, as shown in figure 19 . The switch does not interpret or store this information. Figure 19 network login operation when the client device and radius server have exchanged authentication information, the switch receives either an authentication s...
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What is switch management login? 77 ■ the radius server in your network is operational. ■ if the radius server fails or is unavailable, client devices will be unable to access the network. ■ network login is not supported on ports configured to operate as members of an aggregated link. ■ some client...
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78 c hapter 10: m aking y our n etwork s ecure manageable network device is a commonplace security measure. If the local switch database is enabled, the network administrator must have local access to each switch to securely change user name and password information. This can be time consuming, tedi...
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What is switch management login? 79 figure 20 radius authentication operation important considerations this section contains some important considerations when using radius authentication of switch management login on the switch 3226 and switch 3250. ■ before you enable radius authentication you mus...
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80 c hapter 10: m aking y our n etwork s ecure what is radius? Remote authentication dial-in user service (radius) is an industry standard protocol for carrying authentication, authorization and configuration information between a network device and a shared authentication server. Transactions betwe...
Page 81: Ip R
11 ip r outing routing is a method for distributing traffic throughout an ip network. It is used to join lans at the network layer (layer 3) of the open systems interconnection (osi) model. A router provides both filtering and bridging functions across the network. This chapter explains routers, pro...
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82 c hapter 11: ip r outing what is routing? Routing distributes packets over potentially dissimilar networks. A router is the device that accomplishes this task. Your switch, as a layer 3 device, can act as a router. Routers typically: ■ connect networks. ■ connect subnetworks (or client/server net...
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What is ip routing? 83 what is ip routing? An ip router, unlike a bridge, operates at the network layer of the osi reference model. The network layer is also referred to as layer 3. An ip router routes packets by examining the network layer address (ip address). Bridges use data link layer mac addre...
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84 c hapter 11: ip r outing benefits of ip routing ip routing provides the following features and benefits: ■ economy — because you can connect several segments to the same subnetwork with routing, you can increase the level of segmentation in your network without creating new subnetworks or assigni...
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Ip routing concepts 85 figure 23 routing interfaces routing tables with a routing table, a router or host determines how to send a packet toward its ultimate destination. The routing table contains an entry for every learned and locally defined network. The size of the routing table is dynamic and c...
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86 c hapter 11: ip r outing routing table data is updated statically or dynamically: ■ statically — you manually enter static routes in the routing table. You can define up to 10 (maximum) static routes. Static routes are useful in environments where no routing protocol is used or where you want to ...
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Multiple ip interfaces per vlan 87 this model allows the switch to route the packet first, and then if the packet cannot be routed, give the packet to layer 2 to be bridged by the vlan. This scheme gives you the flexibility to define router interfaces on top of several bridge ports. The “routing ove...
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88 c hapter 11: ip r outing implementing ip routing to route network traffic using ip, you must perform these tasks in the following order: 1 configure vlans. 2 establish ip nterfaces on those vlans. Configuring ip vlans if you want to use ip routing, you must first configure the vlan to use ip. You...
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Implementing ip routing 89 defining an ip interface after you decide the vlan index, ip address, and subnet mask for each ip interface you want to create, you can define each interface using the command line interface or the web interface. Before you assign ip addresses, map out the entire network a...
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90 c hapter 11: ip r outing ■ static routes take precedence over dynamically learned routes to the same destination. ■ static routes are included in periodic rip updates sent by your layer 3 switch. Ip routing protocols ip protocols are a set of uniquely defined interactions that allow data communic...
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Ip routing protocols 91 router mode the available settings for router mode are as follows: ■ disabled — the switch ignores all incoming rip packets and does not generate any rip packets of its own. ■ enabled — the switch broadcasts rip updates and processes incoming rip packets. Update time this swi...
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92 c hapter 11: ip r outing ■ ripv1 – route information is broadcast periodically to other routers on the network using the advertisement list for rip-1 updates. ■ ripv2 – route information is multicast periodically to other routers on the network using the multicast address of 224.0.0.9. This metho...
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Ip routing protocols 93 advertisement address the switch uses the advertisement address to advertise routes to other stations on the same network. Each interface that you define uses a directed broadcast address as the advertisement address. The switch uses this address for sending updates. Rip-1 ve...
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94 c hapter 11: ip r outing network. Udp packets that rely on the bootp relay agent are modified and then forwarded through the router. ■ dynamic host configuration protocol (dhcp) a host can retrieve its own configuration information including ip address, from a dhcp server through the ip network. ...
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Ip routing protocols 95 figure 25 example of an arp cache if the ip address does not have a corresponding mac address, the host or router broadcasts an arp request packet to all the devices on the network. The arp request contains information about the target and source addresses for the protocol (i...
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96 c hapter 11: ip r outing figure 27 example of arp cache updated with arp reply after the mac address is known, the host or router can send the packet directly to the next hop. Arp proxy arp proxy allows a host that has no routing ability to determine the mac address of a host on another network o...
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Advanced ip routing options 97 figure 28 arp proxy internet control message protocol (icmp) because a router knows only about the next network hop, it is not aware of problems that may be closer to the destination. Destinations may be unreachable if: ■ hardware is temporarily out of service. ■ you s...
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98 c hapter 11: ip r outing.
Page 99: Onfiguration
A c onfiguration r ules configuration rules for gigabit ethernet gigabit ethernet is designed to run over several media: ■ single-mode fiber optic cable, with connections up to 5 km (3.1 miles). Support for distances over 5 km is supported depending on the module specification. ■ multimode fiber opt...
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100 a ppendix a: c onfiguration r ules configuration rules for fast ethernet the topology rules for 100 mbps fast ethernet are slightly different to those for 10 mbps ethernet. Figure 29 illustrates the key topology rules and provides examples of how they allow for large-scale fast ethernet networks...
Page 101
Configuration rules for fast ethernet 101 ■ a total network span of 325 m (1066 ft) is allowed in single-repeater topologies (one hub stack per wiring closet with a fiber link to the collapsed backbone). For example, a 225 m (738 ft) fiber link from a repeater to a router or switch, plus a 100 m (32...
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102 a ppendix a: c onfiguration r ules.
Page 103: Etwork
B n etwork c onfiguration e xamples this chapter contains the following sections: ■ simple network configuration example ■ desktop switch example ■ advanced network configuration example ■ edge switch example.
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104 a ppendix b: n etwork c onfiguration e xamples simple network configuration example the following illustration shows how the switch 3226 and switch 3250 can be used in your network. Desktop switch example the example in figure 30 shows how a switch 3226 can be used for a group of users that requ...
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Advanced network configuration example 105 advanced network configuration example the following illustration shows a network example that illustrates how you can set up your network for optimum performance using some of the features supported by your switch. Edge switch example the example in figure...
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106 a ppendix b: n etwork c onfiguration e xamples.
Page 107: Ip A
C ip a ddressing this chapter provides some background detail on the ip information that needs to be assigned to your switch to enable you to manage it across a network. The topics covered are: ■ ip addresses ■ subnets and subnet masks ■ default gateways ip addressing is a vast topic and there are w...
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108 a ppendix c: ip a ddressing 192.168.100.X (where x is a number between 1 and 254) with a subnet mask 255.255.255.0. These suggested ip addresses are part of a group of ip addresses that have been set aside specially for use “in house” only. Caution: if your network has a connection to the extern...
Page 109
Ip addresses 109 referred to as a field or an octet. Decimal notation converts the value of each field into a decimal number, and the fields are separated by dots. Figure 33 dotted decimal notation for ip addresses the decimal value of an octet whose bits are all 1s is 255. Network portion the locat...
Page 110
110 a ppendix c: ip a ddressing subnets and subnet masks you can divide your ip network into sub-networks also known as subnets. Support for subnets is important because the number of bits assigned to the device part of an ip address limits the number of devices that may be addressed on any given ne...
Page 111
Subnets and subnet masks 111 as shown in this example, the 32 bits of an ip address and subnet mask are usually written using an integer shorthand. This notation translates four consecutive 8-bit groups (octets) into four integers that range from 0 through 255. The subnet mask in the example is writ...
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112 a ppendix c: ip a ddressing the subnet mask 255.255.255.255 identifies a specific host. The ip address 255.255.255.255 is reserved as the default broadcast address. Default gateways a gateway is a device on your network which is used to forward ip packets to a remote destination. An alternative ...
Page 113: Dvanced
D a dvanced ip r outing c oncepts this chapter provides some additional background detail on the ip information that can be assigned to your switch to enable you to manage it across a network. These are advanced features and are not required for operating your switch in your network. The topics cove...
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114 a ppendix d: a dvanced ip r outing c oncepts maintenance and the risk of creating erroneous addresses unless you plan the addressing scheme properly. Guidelines for using vlsms consider the following guidelines when you implement vlsms: ■ when you design the subnetwork scheme for your network, d...
Page 115: 11111100
Supernetting 115 routing table entry. (see rfc 1519 for detailed information about supernetting.) to do this, supernet addressing does something very different from traditional tcp/ip routing (which allows only one netmask per network). In supernet routing, each supernet can be assigned its own netm...
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116 a ppendix d: a dvanced ip r outing c oncepts supernet twice as large. So, a supernet composed of 8 class c networks would actually have 3 zeroes (8 = 2 3 ). This would seem very limited since it restricts you to using groups that nicely fit into a power of 2 (1, 2, 4, 8, 16...). However, inconve...
Page 117: 255.255.252.0
Supernetting 117 figure 37 selecting a range of addresses supernet example the four networks in figure 38 are all connected to the same internet service provider (isp). The isp has decided to use supernetting to reduce the size of the routing tables and improve throughput. Figure 38 supernet example...
Page 118
118 a ppendix d: a dvanced ip r outing c oncepts ■ supernet 3 requires 7 class c address spaces. Since 7 isn't a power of 2, we have to round it up to eight. This gives it a netmask of 255.255.248.0. ■ supernet 4 is a single class c network, making it’s netmask 255.255.255.0 now, assign ranges of ad...
Page 119: Lossary
G lossary 3com network supervisor the 3com network management application used to manage 3com’s networking solutions. 10base-t the ieee specification for 10 mbps ethernet over category 3, 4 or 5 twisted pair cable. 100base-fx the ieee specification for 100 mbps fast ethernet over fiber-optic cable. ...
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120 g lossary bandwidth the information capacity, measured in bits per second, that a channel can transmit. The bandwidth of ethernet is 10 mbps, the bandwidth of fast ethernet is 100 mbps, and the bandwidth of gigabit ethernet is 1000 mbps. Baud the signalling rate of a line, that is, the number of...
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121 devices transmit simultaneously, a collision occurs and the colliding devices delay their retransmissions for a random length of time. Dhcp dynamic host control protocol. A protocol that lets you centrally manage and automate the assignment of internet protocol (ip) addresses in an organization'...
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122 g lossary ftp file transfer protocol. A protocol based on tcp/ip for reliable file transfer. Full duplex a system that allows packets to be transmitted and received at the same time and, in effect, doubles the potential throughput of a link. Gateway see router . Gigabit ethernet ieee standard 80...
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123 ieee std 802.1w-2001 a standard that defines rapid spanning tree protocol (rstp) behavior. Ieee std 802.1x-2001 a standard that defines port-based network access control behavior. Ietf internet engineering task force. An organization responsible for providing engineering solutions for tcp/ip net...
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124 g lossary lan local area network. A network of endstations (such as pcs, printers, servers) and network devices (hubs and switches) that cover a relatively small geographic area (usually not larger than a floor or building). Lans are characterized by high transmission speeds over short distances...
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125 multicast a packet sent to a specific group of endstations on a network. Multicast filtering a system that allows a network device to only forward multicast traffic to an endstation if it has registered that it would like to receive that traffic. Nic network interface card. A circuit board insta...
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126 g lossary rip routing information protocol. An interior gateway protocol for tcp/ip networks. Rip uses distance-vector algorithms (dva) to calculate least-hops routes to a destination. Rmon ietf remote monitoring mib. A mib that allows you to remotely monitor lans by addressing up to nine differ...
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127 ssl secure sockets layer. A protocol used for encrypting network traffic. It is commonly used to encrypt http traffic between and browser and a web server. Standby port the port in a resilient link that takes over data transmission if the main port in the link fails. Stp see spanning tree protoc...
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128 g lossary unicast a packet sent to a single endstation on a network. Variable length subnet mask (vlsm) a suffix to an ip address that indicates the size of the subnet that contains it. Taking the address 192.168.1.1/24 as an example, the vlsm is /24 and indicates that the first 24 bits of the a...
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I ndex 129 i ndex numbers 802.1d priority levels 48 traffic classification 48 a access control lists 73 addresses classes 109 ip 88, 107 advertise rip mode 91 advertisement address 93 aggregated links 14, 23 aging time, definition 46 alarm events 58 alarms (rmon group) 56, 57 arp (address resolution...
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130 i ndex i icmp (internet control message protocol) description 97 location in osi reference model 83 ieee std 802.1q-1998 61 ieee std 802.3-2002 flow control 15, 22 igmp multicast filtering 31 index, vlan interface 88 interfaces ip 89 internet addresses 107 internic 108 ip (internet protocol) add...
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I ndex 131 r radius 77, 80 authentication 77 rapid spanning tree protocol (rstp) 16, 36 registered ip address, obtaining 108 remote monitoring. See rmon restore 15 rip (routing information protocol) advertisement address 93 defined 90 location in osi reference model 83 poison reverse 92 route config...
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132 i ndex.