Advantages of Campus Wide VLANs

As the paragraphs that follow attest, there are some alluring aspects to the flat earth approach. First, the campus-wide VLANs model allows network designers to create a direct Layer 2 path from end stations to the most commonly used servers. By deploying Layer 2 switching in all three layers of the access distribution core model, campuswide VLANs should dramatically increase available bandwidth. The second advantage of the campus-wide VLANs model is that VLANs can be used to provide logical...

And Active Topology

The setup in Figure 6-21 clearly illustrates the basic objective of the Spanning-Tree Protocol make one bridge the center of the universe and then have all other bridges locate the shortest path to that location (all roads lead to Rome). This results in an active topology consisting of spoke-like branches that radiate out from the Root Bridge. Notice that the Root Bridge is acting as the central switching station for all traffic between the four branches and must be capable of carrying this...

Answers to Chapter 4 Review Questions

1 What happens if you replace the active Supervisor module A If you replace the active module, the standby becomes the active Supervisor module. If the configuration files differ between the two, the now active Supervisor updates the configuration on the replacement module. Likewise, if any software images differ, the now active module updates the replacement unit. 2 If your redundant Supervisor engines are running software version 4.1, the uplink ports on the standby engine are disabled until...

Answers to Chapter 5 Review Questions

1 Early in this chapter, it was mentioned that you can determine the extent of a broadcast domain in a switched network without configuration files. How do you do it A You can use a brute force approach where you systematically attach a traffic source on a port on a switch configured to generate broadcasts. With a network analyzer, you then check every port in the system to observe where the broadcast appeared. Every port where the broadcast is seen is a member of the same VLAN as the source....

Answers to Chapter 6 Review Questions

1 Summarize the three-step process that STP uses to initially converge on an active topology. A The three-step process is as follows Elect a single Root Bridge for the entire bridged network. Elect one Root Port for every non-Root Bridge. Elect one Designated Port for every segment. 2 How many of the following items does the network shown in Figure 6-24 contain Root Bridges, Root Ports, Designated Ports Assume all devices are operational. A The network in Figure 6-24 contains the following One...

ATM Core

The advantage of this approach is that it uses cost-effective Ethernet technology in the potentially large number of IDF closets. This design is often deployed using the campus-wide VLAN model to extend the speed of ATM through the Ethernet links. The downside is that it creates a large number of Layer 2 loops where redundant MDF-to-IDF links are used. Unfortunately, these links have been shown to create Spanning Tree loops that can disable the entire campus network. Furthermore, it is harder...

ATM Network

Ffpe Protein

Other VLAN types use combinations of Layer 2, Layer 3, or even Layer 4 to create shortcuts in a system. Layer 4 switching creates shortcuts based upon the Layer 3 addresses and upon the Layer 4 port values. This is sometimes called application switching and provides a higher level of granularity for switching. Chapter 11 provides a more thorough discussion on this subject in the context of MLS. Table 5-1 summarizes the various switch types found in the industry. Table 5-1 summarizes the various...

ATM Resiliency

ATM also provides physical layer recovery. However, the failover time is longer than for FDDI. In an ATM network, a cable or interface failure can occur at the Catalyst or between ATM switches. If the failure occurs between ATM switches, the Catalyst requests the ATM network to re-establish a connection to the destination client(s). The ATM network attempts to find an alternate path to complete the connection request. This happens automatically. Figure 8-18 shows a Catalyst attached to two ATM...

Attach to Three ELANs

You need the router shown in Figure 8-13 if workstations in one VLAN desire to communicate with workstations in another VLAN. The router can reside on the LAN side of the Catalysts, but this example illustrates the router on the ATM side. When a station in VLAN 1 attempts to communicate with a station in VLAN 2, the Catalyst bridges the frame out LEC 1 to the router. The router, which also has three clients, routes the frame out the LEC which is a member of ELAN 2 to the destination Catalyst....

B after a Link Failure

Therefore, the Spanning Tree Max Age and Forward Delay parameters can be safely reduced to 12 and 9 seconds, respectively (assuming the default Hello Time of 2 seconds). The safest and simplest way to accomplish this is to use the set spantree root macro to automatically modify the appropriate Spanning Tree parameters. As a result, convergence time can be reduced from a default of 30-50 seconds to 18-30 seconds. To further speed Spanning Tree convergence, UplinkFast, BackboneFast, and PortFast...

Backbone Fast

BackboneFast is a complementary (and patented) technology to UplinkFast. Whereas UplinkFast is designed to quickly respond to failures on links directly connected to leaf-node switches, it does not help in the case of indirect failures in the core of the backbone. This is where BackboneFast comes in. Don't expect BackboneFast to provide the two to three second rollover performance of UplinkFast. As a Max Age optimization, BackboneFast can reduce the indirect failover performance from 50 to 30...

Bottom line Controlling VTP in Large Networks

In large networks, these issues multiply and can develop into situations making you want to disable trunking, VTP, or other aspects of VLANs. Clearly, trunking remains as a necessary element of networking life. It is not practical to deploy a large network without trunks because of the number of resources that you consume with multiple access links. Therefore, trunks remain. However, as previously mentioned, we have methods of minimizing some of the negative side effects of trunking. VTP is...

Bridge Priority Load Balancing

How can Bridge Priority be used to accomplish load balancing in the two-building campus illustrated in Figure 7-17 As discussed in the previous section, the IDF switch (Cat-2C) found multiple equal cost paths to the Root Bridge. This caused the third decision criterion, Bridge ID, to be evaluated. Because Cat-2A and Cat-2B were using the default Bridge ID values, Cat-2A had the lower BID for all VLANs (32,768.AA-AA-AA-AA-AA-AA versus 32,768.BB-BB-BB-BB-BB-BB). This is precisely what ruined the...

Bundling Ports

When bundling ports for EtherChannel using early EtherChannel-capable line modules, you must follow a couple of rules Use contiguous ports for a bundle. All ports must belong to the same VLAN. If the ports are used for trunks, all ports must be set as a trunk. If you set the ports to trunk, make sure that all ports pass the same VLANs. Ensure that all ports at both ends have the same speed and duplex settings. You cannot arbitrarily select ports to bundle. See the following descriptions for...

Calculating Endto End BPDU Propagation Delay for Max

End-to-End BPDU Propagation Delay is the amount of time that it takes for a BPDU to travel from one edge of the network to the other edge of the network. The 802.1D specification assumes that up to three BPDUs can get lost along the way, the maximum distance between any two nodes in the network is seven bridge hops, and each bridge can take up to one second to propagate a BPDU after receiving it. Also, the default Hello Time interval of two seconds is assumed. Table 7-2 documents these...

Calculating Maximum Frame Lifetime

In addition to the delay that it takes for a bridge to close the door by blocking the port, the algorithm needs to account for frames that have already gone out the door and are running around the network looking for their final destination. This is done with the Maximum Frame Lifetime. Maximum Frame Lifetime can be calculated with the following formula (diax transit delay) + med access delay (7 x 1) + .5 8 seconds (rounded) The diax transit_de a part allows time for frames to die out, whereas...

Campus Wide VLANs Model

As people began to notice their router and hub networks struggling to keep up with traffic demands, they looked for alternate approaches. Many of these organizations decided to implement campus-wide VLANs, also known as the flat earth and end-to-end VLAN approach to network design. Campus-wide VLANs strive to eliminate the use of routers. Because routers had become a significant bottleneck in campus networks, people looked for ways to minimize their use. Because broadcast domains still needed...

Catalyst 50006000 CLI Syntax Conventions

All well-documented equipment uses a standard representation for interpreting commands. The Catalyst is no exception. Cisco documents how to interpret the printed commands of its documentation. Table 4-1 summarizes the command syntax conventions used in the Catalyst documentation and in this book. Table 4-1. Catalyst Syntax Conventions Commands and keywords that are entered literally as shown are in boldface. Arguments for which you supply values are in italics. Elements in square brackets are...

Catalyst VLAN Configuration

Some VLAN components assign stations to VLANs based upon MAC addresses. The Catalyst, on the other hand, associates ports to a VLAN. Any device attached to the port belongs to the VLAN describing the switch interface. Even if a shared hub attaches to the port, all stations on the hub belong to the same VLAN. This is called a port-centric approach to VLANs. To configure VLANs in a Catalyst, you must first plan the VLAN membership and then assign ports to the correct VLAN. Planning VLAN...

Changing Traffic Patterns

Any effective campus design must take traffic patterns into account. Otherwise, switching and link bandwidth are almost certainly wasted. The good news is that most modern campus networks follow several trends that create unmistakable flows. This section discusses the traditional campus traffic patterns and shows how popular new technologies have drastically changed this. The earliest seeds of today's campus networks began with departmental servers. In the mid-1980s, the growth of inexpensive...

Configuring the Catalyst

This chapter covers the following key topics Catalyst 5000 6000 CLI Syntax Conventions Provides the standard Cisco representation for interpreting commands administered on Catalyst switches. Catalyst 5000 Configuration Methods Provides information on how to operate under the Console, Telnet, and TFTP configuration modes for Catalyst configuration. Using the Catalyst 5000 6000 Command-Line Interface Describes command-line recall, editing, and help for the Catalyst 5000 series. Passwords Provides...

Understanding Spanning Tree

The authors would like to thank Radia Perlman for graciously contributing her time to review the material in this chapter. This chapter covers the following key topics What Is Spanning Tree and Why Use Spanning Tree Briefly explains the purpose of the Spanning-Tree Protocol (STP). Explains why some form of loop-prevention protocol is required to prevent broadcast storms and bridge table corruption. Four-Step STP Decision Sequence Describes the process that the Spanning-Tree Protocol uses for...

Trunking with LAN Emulation

This chapter covers the following key topics A Brief ATM Tutorial For engineers accustomed to working in frame-based technologies such as Ethernet, ATM can seem strange and mysterious. However, as this section discusses, it is based on many of the same fundamental concepts as technologies that are probably more familiar. LANE Theory of Operation Introduces the theory used by LAN Emulation (LANE) to simulate Ethernet and Token Ring networks over an ATM infrastructure. Explores the conceptual...

Connected

Figure 7-6 illustrates the conversation that ensues between Cat-C and Cat-B. Figure 7-6 Exception Processing of Configuration BPDUs Figure 7-6 Exception Processing of Configuration BPDUs As discussed in Chapter 6, Cat-C initially assumes it is the Root Bridge and immediately starts sending BPDUs to announce itself as such. Because the Root Bridge is currently down, Cat-B Port-1 2 has stopped sending Configuration BPDUs as a part of the normal processing. However, because Cat-B Port-1 2 is the...

Console Configuration

The Catalyst 5000 series Supervisor module has one physical console connection. For a Supervisor I or a Supervisor II, the connection is an EIA-232 25-pin connection. For a Supervisor III module, the connection is an RJ-45 connector. Make sure that you know which kind of Supervisor module you are working with to ensure that you can attach to the console. The console has an interesting feature in that it can operate in one of two modes either as a console or slip interface. When used as a...

Creation Process

Host-B receives the IP ARP request. Recognizing its IP address in the ARP packet, it builds an IP ARP reply packet. Figure 9-19 illustrates the reply. In this case, the ARP message contains the MAC address in question. Also notice that ARP unicasts the reply back to the source node it is not sent to all nodes via the broadcast address. The LEC-B Catalyst receives the IP ARP reply. Having just added a bridging table entry for AAAA.AAAA.AAAA in Step 5, the frame is forwarded to the LANE...

Design Alternatives

As with Design 1, hundreds of permutations are possible for Design 2. This section briefly discusses some of the more common alternatives. First, as shown in Figure 17-5, Design 2 calls for a pair of 8500s for the server farm. Figure 17-7 illustrates a potential layout for the server farm under Design 2. Figure 17-7 Detail of Server Farm for Design 2 Figure 17-7 Detail of Server Farm for Design 2 In this plan, a pair of Catalyst 6500 switches are directly connected to the backbone via Cat-B1-0B...

Design Discussion

This section introduces some of the design choices that were made for the first design. However, before diving into the specifics, it is worth pausing to look at the big picture of Design 1. As discussed earlier, both designs use Layer 3 switching in the MDF distribution layer devices. This isolates each building behind a Layer 3 barrier to provide scalability and stability. By placing each building behind the safety of an intelligent Layer 3 router, it is much more difficult for problems to...

Disabling STP

It might be necessary to disable Spanning Tree in some situations. For example, some network administrators disable STP in frustration after not being able to resolve STP bugs and design issues. Other people disable STP because they have loop-free topologies. Some shops resort to disabling STP because they are not aware of the PortFast feature (not to mention its interaction with PAgP as discussed earlier). If you do need to disable STP, Catalysts offer the set spantree disable command. On most...

Disadvantages of Campus Wide VLANs

There are also some significant downsides to the campus-wide VLANs model Large and overlapping Spanning Tree domains It is easy for a problem in one VLAN to deplete bandwidth in all VLANs across trunk links Many networks using campus-wide VLANs must resort toeliminating all redundancy to achieve network stability Most modern traffic violates the stay in one subnet rule employed by the campus-wide VLAN model Modern routers are not a bottleneck The paragraphs that follow provide more detailed...

Dont Forget PLANs

When creating a new design or when your first one or two attempts at solving a particular problem fail, redraw your VLAN design using physical LANs (PLANs). In other words, take the logical topology created through the use of virtual LANs and redraw it using PLANs. PLAN is a somewhat tongue-in-cheek term the author coined to describe a very serious issue. For some reason, the human brain is almost guaranteed to forget all knowledge of IP subnetting when faced with virtual LANs. People spend...

Duplicate Ring Protocol DRiP

In a Token Ring environment, each ring has a unique ring number identifying it for source-route bridging. Similarly, in a switched Token Ring, except for the default and backup TrCRFs mentioned earlier, each TrCRF has a unique ring number. If an administrator accidentally misconfigures another TrCRF with the same ring number, shown in Figure 3-11, the Token Ring switching process gets confused. Figure 3-11 Do not attempt this. Duplicate ring numbers are not allowed on multiple switches. Figure...

Endto End Distance

Another limitation on extending networks with repeaters focuses on distance. An Ethernet link can extend only so far before the media slotTime specified by Ethernet standards is violated. As described in Chapter 1, the slotTime is a function of the network data rate. A 10 Mbps network such as 10BaseT has a slotTime of 51.2 microseconds. A 100 Mbps network slotTime is one tenth that of 10BaseT. The calculated network extent takes into account the slotTime size, latency through various media such...

Ether Channel Development

EtherChannel defines a bundling technique for standards-based segments such as Fast Ethernet and Gigabit Ethernet. It does not cause the links to operate at clock rates different than they were without bundling. This makes the segments non Fast Ethernet- or Gigabit Ethernet-compliant. EtherChannel enables devices to distribute a traffic load over more than one segment while providing a level of resiliency that does not involve Spanning Tree or other failover mechanisms. The IEEE is examining a...

Ethernet Resiliency

Ethernet options (both Fast Ethernet and Gigabit Ethernet) rely upon Spanning Tree for resiliency. Spanning Tree, discussed in Chapter 6, Understanding Spanning Tree, operates at Layer 2, the data link layer. Components detect failures when they fail to receive BPDUs from the Root Bridge. Spanning Tree recovery can take as much as 50 seconds depending upon at what values you set the timers. EtherChannel, both Fast and Gigabit, provide local resiliency. Figure 8-19 shows two Catalysts...

Example 101 LANE and MPOA Component Addresses

Router show lane default interface ATM1 0 LANE Client LANE Server LANE Bus LANE Config Server note ** is the subinterface number byte in hex router show mpoa default interface ATM1 0 MPOA Server 47.009181000000009092BF7401. 0090AB16500C.** MPOA Client 47.009181000000009092BF7401. 0090AB16500D.** note ** is the MPS MPC instance number in hex Note that the esi portion highlighted in italics of the MPS and MPC NSAP continue to increment beyond the esi portion of the LECS NSAP address. The selector...

Example 1019 MPOA Resolution Reply from debug

MPOA CLIENT received a MPOA_RESOLUTION_REPLY packet of size 127 bytes on ATM1 0 vcd 832 dumping nhrp packet fixed part op_type 135 (MPOA_RESOLUTION_REPLY), shtl 20, sstl 0 mandatory part src_proto_len 4, dst_proto_len 4, flags 0, request_id 2 src_nbma_addr src_prot_addr 0.0.0.0 dst_prot_addr 3.0.0.1 cie 0 code 0, prefix_length 0, mtu 1500, holding_time 1200 cli_addr_tl 20, cli_saddr_tl 0, cli_proto_len 0, preference 0 cli_nbma_addr tlv 0 type 4097, length 4 data 15 05 00 01 tlv 1 type 4096,...

Example 107 Output from show mpoa server Command

Router show mpoa server MPS Name mps, MPS id 0, Interface ATM1 0, State up network-id 1, Keepalive 10 secs, Holding time 1200 secs Keepalive lifetime 35 secs, Giveup time 40 secs MPS actual operating address Lane clients bound to MPS mps ATM1 0.1 ATM1 0.2 Discovered neighbours MPC vcds 75(R,A) MPC vcds 77(R,A) In Example 10-7, the MPS sees two MPC neighbors. The output displays the virtual circuits used to communicate with each of the MPCs. These circuits should not experience idle timeouts and...

Example 1118 HSRP Configuration for RouterA

Interface EthernetO description Link to wiring closet Catalysts ip address 10.1.1.2 255.255.255.0 standby 1 priority 110 standby 1 preempt standby 1 ip 10.1.1.1 standby 1 track Ethernet1 15 interface Ethernet1 description Link to backbone ip address 10.1.2.2 255.255.255.0 The real IP address is assigned with the usual ip address command. HSRP parameters are then configured using various standby commands. The shared IP address is added with standby group_number ip ip_address command. This...

Example 1124 Using Bridge Groups to Bridge between VLANs

Interface FastEthernet0 0 0 no ip address interface FastEthernet0 0 0.1 encapsulation isl 1 ip address 10.1.1.1 255.255.255.0 interface FastEthernet0 0 0.2 encapsulation isl 2 ip address 10.1.2.1 255.255.255.0 ipx network 2 bridge-group 1 interface FastEthernet0 0 0.3 encapsulation isl 3 ip address 10.1.3.1 255.255.255.0 ipx network 3 bridge-group 1 interface FastEthernet0 0 0.4 encapsulation isl 4 ip address 10.1.4.1 255.255.255.0 ipx network 4 bridge 1 protocol ieee The configuration in...

Example 1126 Routing IP and IPX While Bridging All Other Protocols

Interface FastEthernet0 0 0 no ip address interface FastEthernet0 0 0.1 encapsulation isl 1 ip address 10.1.1.1 255.255.255.0 ipx network 1 bridge-group 1 interface FastEthernet0 0 0.2 encapsulation isl 2 ip address 10.1.2.1 255.255.255.0 ipx network 2 bridge-group 1 bridge 1 protocol ieee The configuration in Example 11-26 routes IP and IPX between VLANs 1 and 2 but also allows non-routable traffic such as NetBIOS NetBEUI to be bridged through the router. However, this also merges the Spanning...

Example 114 Using the RSM for Extended pings

RSM ping Protocol ip Target IP address 10.1.1.55 Repeat count 5 100000 Datagram size 100 1024 Timeout in seconds 2 Extended commands n y Source address or interface Type of service 0 Set DF bit in IP header no y Validate reply data no y Data pattern 0xABCD 0000 Loose, Strict, Record, Timestamp, Verbose none Sweep range of sizes n Type escape sequence to abort. Sending 100000, 1024-byte ICMP Echos to 10.1.6.100, timeout is 2 seconds Packet has data pattern 0x0000 Example 11-4 illustrates the use...

Example 124 show vtp domain Output

Console> (enable) show vtp domain Domain Name Domain Index VTP Version Local Mode ---------wally 1 2 server - Vlan-count Max-vlan-storage Config Revision 5 1023 0 disabled Last Updater V2 Mode Pruning PruneEligible on ----------------------- 0.0.0.0 disabled disabled 2-1000 Console> (enable) For example, in the highlighted portion of Example 12-4, the Catalyst's display indicates that it belongs to the domain wally. If the Domain Name field is blank, the domain is NULL. VTP domain names are...

Example 125 Clearing a VLAN in a Management Domain

Console> (enable) clear vlan 10 This command will deactivate all ports on vlan 10 in the entire management domain Do you want to continue(y n) n y Vlan 10 deleted Console> (enable) Clearing a VLAN does not cause the ports in the management domain to reassign themselves to the default VLAN 1. Rather, the Catalysts keep the ports assigned to the previous VLAN, but in an inactive state. You need to reassign ports to an active VLAN before the attached devices can communicate again.

Example 163 Output from show port counters

Console> show port counters Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize -- 1 1 0 0 0 0 0 1 2 0 0 0 0 0 4 1 0 0 0 0 0 4 2 0 0 0 0 0 4 3 0 0 0 0 0 4 4 0 0 0 0 0 Port Single-Col Multi-Coll Late-Coll Excess-Col Carri-Sen Runts --------------------1 1 12 0 0 0 0 0 - 1 2 0 0 0 0 0 0 0 4 1 0 0 0 0 0 0 0 4 2 0 0 0 0 0 0 0 4 3 0 0 0 0 0 0 0 4 4 0 0 0 0 0 0 0 Ler Port CE-State Conn-State Type Neig Con Est Alm Cut Lem-Ct Lem-Rej-Ct ------------------------------3 1 isolated connecting A U no 9 9 7...

Example 1710 SNMP Trap Configuration

Cat-B2-1A> (enable) set snmp trap 10.100.100.21 trapped SNMP trap receiver added. Cat-B2-1A> (enable) set snmp trap enable module SNMP module traps enabled. Cat-B2-1A> (enable) set snmp trap enable chassis SNMP chassis alarm traps enabled. Cat-B2-1A> (enable) set snmp trap enable bridge SNMP bridge traps enabled. Cat-B2-1A> (enable) set snmp trap enable auth SNMP authentication traps enabled. Cat-B2-1A> (enable) set snmp trap enable stpx SNMP STPX traps enabled. Cat-B2-1A>...

Example 1714 Spanning Tree Configuration

Cat-B2-0B> (enable) set spantree root 20 dia 3 hello 2 VLAN 20 bridge priority set to 8192. VLAN 20 bridge max aging time set to 12. VLAN 20 bridge hello time set to 2. VLAN 20 bridge forward delay set to 9. Cat-B2-0B> (enable) Cat-B2-0B> (enable) set spantree root secondary 21 dia 3 hello 2 VLAN 21 bridge priority set to 16384. VLAN 21 bridge max aging time set to 12. VLAN 21 bridge hello time set to 2. VLAN 21 bridge forward delay set to 9. Cat-B2-0B> (enable) Cat-B2-0B> (enable)...

Example 1715 Port and Trunk Configuration

Cat-B2-0B> (enable) set port name 5 1 Gigabit link to Cat-B2-1A Port 5 1 name set. Cat-B2-0B> (enable) set port name 5 2 Gigabit link to Cat-B2-2A Port 5 2 name set. Cat-B2-0B> (enable) set port name 5 3 Gigabit link to Cat- B2-0A Port 5 3 name set. Cat-B2-0B> (enable) Cat-B2-0B> (enable) set port speed 1 1 100 Port(s) 1 1 speed set to 100Mbps. Cat-B2-0B> (enable) set port duplex 1 1 full Port(s) 1 1 set to full-duplex. Cat-B2-0B> (enable) set port name 1 1 Link to Cat-B2-3A Port...

Example 1716 Configuring Passwords Banner System Information Dns Ip Permit List IGMP Snooping SNMP and Syslog

Cat-B2-0B> (enable) Cat-B2-0B> (enable) set password Enter old password Enter new password Retype new password Password changed. Cat-B2-0B> (enable) Cat-B2-0B> (enable) set enablepass Enter old password Enter new password Retype new password Password changed. Cat-B2-0B> (enable) Cat-B2-0B> (enable) Cat-B2-0B> (enable) set banner motd PRIVATE NETWORK -- HACKERS WILL BE SHOT MOTD banner set Cat-B2-0B> (enable) set system location Building 2 MDF System location set. Cat-B2-0B>...

Example 1717 Full Catalyst Configuration for CatB20B

Begin set password 1 FMFQ HfZR5DUszVHIRhrz4h6V70 set enablepass 1 FMFQ HfZR5DUszVHIRhrz4h6V70 set prompt Cat-B2-0B> set length 24 default set logout 20 set banner motd CPRIVATE NETWORK -- HACKERS WILL BE SHOTM C system set system baud 9600 set system modem disable set system name Cat-B2-0B set system location Building 2 MDF set system contact Joe x111 snmp set snmp community read-only lesspublic set snmp community read-write moreprivate set snmp community read-write-all mostprivate set snmp...

Example 1718 Full RSM Configuration for CatB20B

service timestamps log datetime localtime service password-encryption hostname Cat-B2-0B-RSM enable secret 5 1 JiA8 oFVSrScIZX2BnqDV W9m11 ip domainname happy.com ip name-server 10.100.100.42 ip name-server 10.100.100.68 ipx routing 00e0.4fb3.68a0 mls rp ip clock timezone EST -5 clock summer-time EDT recurring interface Vlan20 ip address 10.2.20.3 255.255.255.0 ip helper-address 10.100.100.33 ip helper-address 10.100.100.81 no ip redirects mls rp vtp-domain Happy-B2 mls rp management-interface...

Example 172 VTP Configuration

Cat-B2-1A> (enable) set vtp domain Happy-B2 VTP domain Happy-B2 modified Cat-B2-1A> (enable) set vtp mode server VTP domain Happy-B2 modified Cat-B2-1A> (enable) set vlan 20 name B2_Management Vlan 20 configuration successful Cat-B2-1A> (enable) set vlan 21 name B2_Sales Vlan 21 configuration successful Cat-B2-1A> (enable) set vlan 22 name B2_Marketing Vlan 22 configuration successful Cat-B2-1A> (enable) set vlan 23 name B2_Engineering Vlan 23 configuration successful Cat-B2-1A>...

Example 1722 VTP and VLAN Configration

Cat-B2-1A> (enable) set vtp mode transparent VTP domain Happy modified Cat-B2-1A> (enable) Cat-B2-1A> (enable) set vlan 2 name Engineering Vlan 2 configuration successful Cat-B2-1A> (enable) The SC0 interface also uses a different configuration under Design 2. First, the IP address and netmask are obviously different. Second, SC0 is left in VLAN 1, the default. Third, Design 2 calls for two default gateway addresses to be specified with the ip route command (this feature was first...

Example 1724 Spanning Tree Configuration

Cat-B2-1A> (enable) set spantree root 1 dia 2 hello 2 VLAN 1 bridge priority set to 8192. VLAN 1 bridge max aging time set to 10. VLAN 1 bridge hello time set to 2. VLAN 1 bridge forward delay set to 7. Switch is now the root switch for active VLAN 1. Cat-B2- 1A> (enable) Cat-B2-1A> (enable) set spantree root 2 dia 2 hello 2 VLAN 2 bridge priority set to 8192. VLAN 2 bridge max aging time set to 10. VLAN 2 bridge hello time set to 2. VLAN 2 bridge forward delay set to 7. Switch is now the...

Example 174 Spanning Tree Configuration

Cat-B2- 1A> (enable) set spantree portfast 3 1-24,4 1-24,5 1-24,6 124,7 1-24 enable Warning Spantree port fast start should only be enabled on ports connected to a single host. Connecting hubs, concentrators, switches, bridges, etc. to a fast start port can cause temporary Spanning Tree loops. Use with caution. Spantree ports 3 1-24,4 1-24,5 1-24,6 1-24,7 1-24 fast start enabled. Cat-B2-1A> (enable) Cat-B2-1A> (enable) set spantree backbonefast enable Backbonefast enabled for all VLANs...

Example 1811 Placing Two Interfaces in the Same VLAN Default VLAN

NativeMode configure terminal NativeMode(Config) interface FastEthernet5 1 NativeMode(Config-if) switchport NativeMode(Config-if) interface FastEthernet5 2 NativeMode(Config-if) switchport NativeMode(Config-if) end NativeMode Switchports automatically default to VLAN 1 (although this assignment is not made until after the switchport command has been entered). To alter this assignment, you can use additional switchport commands. First, decide if you want the interface to be an access port (one...

Example 1813 Creating Two SVI Interfaces

NativeMode config t NativeMode(Config) interface vlan 1 NativeMode(Config-if) ip address 10.0.1.1 255.255.255.0 NativeMode(Config-if) ipx network 0A000100 NativeMode(Config-if) interface vlan 2 NativeMode(Config-if) ip address 10.0.2.1 255.255.255.0 NativeMode(Config-if) ipx network 0A000200 NativeMode(Config-if) end NativeMode Although all ports are assigned to VLAN 1 by default, the VLAN 1 SVI does not exist by default. To assign Layer 3 attributes to VLAN 1, you must create this SVI.

Example 1822 Configuring the SVI Interfaces

NativeMode(config) interface vlan 1 NativeMode(config-if) ip address 10.0.1.2 255.255.255.0 NativeMode(config-if) ipx network 0A000100 NativeMode(config-if) standby 1 timers 1 3 NativeMode(config-if) standby 1 priority 200 preempt NativeMode(config-if) standby 1 ip 10.0.1.1 NativeMode(config-if) interface vlan 2 NativeMode(config-if) ip address 10.0.2.2 255.255.255.0 NativeMode(config-if) ipx network 0A000200 NativeMode(config-if) standby 2 timers 1 3 NativeMode(config-if) standby 2 priority...

Example 411 Modifying a Catalysts Passwords

Console> (enable) set enablepass Enter old password cntgetin Sorry password incorrect. Console> (enable) set enablepass Enter old password cantgetin Enter new password stillcantgetin Retype new password stillcantgetin Password changed. Console> (enable) set password Enter old password guessthis Enter new password guessthis2 Retype new password guessthis2 Password changed. Console> (enable) Note that italicized text is not displayed in real output. In Example 4-11, the user types in the...

Example 46 Annotated Supervisor Configuration File

Console> (enable) show config begin set password 1 FMFQ HfZR5DUszVHIRhrz4h6V70 set enablepass 1 FMFQ HfZR5DUszVHIRhrz4h6V70 set prompt Console> set length 24 default set logout 20 set banner motd C C system set system baud 9600 set system modem disable set system name set system location set system contact snmp set snmp community read-only public set snmp community read-write private set snmp community read-write-all secret Other SNMP commands deleted IP This sets up the console or slip...

Example 51 Router on a Stick Configuration File

Interface fastethernet 2 0.1 ip address 172.16.10.1 255.255.255.0 ipx network 100 encapsulation isl 100 interface fastethernet 2 0.2 ip address 172.16.20.1 255.255.255.0 ipx network 200 encapsulation isl 200 interface fastethernet 2 0.3 ip address 172.16.30.1 255.255.255.0 encapsulation isl 300 Example 5-1 sets up a trunk between a device and the router. Trunks and InterSwitch Link (ISL) encapsulation are discussed in more detail in Chapter 8. Trunks allow traffic from more than one VLAN to...

Example 53 Assigning Ports to a VLAN

Console> (enable) set vlan 2 2 1-1 8 Usage set vlan < vlan_num> < mod ports > (An example of mod ports is 1 1,2 1-12,3 1-2,4 1-12) Console> (enable) set vlan 2 2 1-2 8 VLAN 2 modified. VLAN 1 modified. VLAN Mod Ports ---------------------------2 2 1-8 Console> (enable) After the port designation is corrected, the Catalyst successfully reassigns the block of ports to VLAN 2. When designating ports, remember that you can assign a block by using hyphens and commas. Do not insert any...

Example 55 VLAN Database Example

PART 1 GLOBAL SETTINGS vmps domain < domain-name> The VMPS domain must be defined. vmps mode open secure The default mode is open. vmps fallback < vlan-name> vmps no-domain-req allow deny The default value is allow. The VMPS domain name MUST MATCH the VTP domain name. vmps domain testvtp vmps mode open vmps fallback default vmps no-domain-req deny PART 2 MAC ADDRESS DATABASE MAC Addresses vmps-mac-addrs address < addr> vlan-name < vlan_name> address 0060.0893.dbc1 vlan-name...

Example 57 Displaying Dynamic Ports

Console> show port Port Name Status Vlan Level Duplex Speed Type 1 1 connect dyn-3 normal full 100 100 BASE-TX 1 2 connect trunk normal half 100 100 BASE-TX 2 1 connect trunk normal full 155 OC3 MMF ATM 3 1 connect dyn- normal half 10 10 BASE-T 3 2 connect dyn-5 normal half 10 10 BASE-T 3 3 connect dyn-5 normal half 10 10 BASE-T Console> (enable) Note the entry for Port 1 1. It has a dynamic VLAN assignment. But the highlighted Port 3 1 is a dynamic port without a VLAN assignment. The...

Example 64 Locating the Root Bridge with show spantree on Cat4 for VLAN

Cat-4 (enable) show spantree VLAN 1 Spanning tree enabled Spanning tree type ieee Designated Root 00-e0-f9-16-28-00 Designated Root Priority 100 Designated Root Cost 19 Designated Root Port 2 1 Root Max Age 10 sec Hello Time 1 sec Forward Delay 10 sec Bridge ID MAC ADDR 00-e0-f9-52-ba-00 Bridge ID Priority 32768 Bridge Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec Port Vlan PortState Cost Priority Fast-Start -------------------- 1 1 1 forwarding 19 32 disabled 1 2 1 forwarding 100 32...

Example 65 Locating the Root Bridge with show spantree on Cat3 for VLAN

Cat-3 (enable) show spantree VLAN 1 Spanning tree enabled Spanning tree type ieee Designated Root 00-e0-f9-16-28-00 Designated Root Priority 100 Designated Root Cost 0 Designated Root Port 1 0 Root Max Age 10 sec Hello Time 1 sec Forward Delay 10 sec Bridge ID MAC ADDR 00-e0-f9-16-28-00 Bridge ID Priority 100 Root Max Age 10 sec Hello Time 1 sec Forward Delay 10 sec Port Vlan Port-State Cost Priority Fast-Start --------- 1 1 1 forwarding 100 32 disabled 1 2 1 forwarding 19 32 disabled Several...

Example 713 Only the Most Recently Specified PortVLAN Cost Value Is Used

Console> (enable) show spantree 1 1 Port Vlan Port-State Cost Priority Fast-Start 1 forwarding 19 31 disabled 1 1 2 forwarding 2000 31 disabled 1 1 3 forwarding 2000 31 disabled 1 1 4 forwarding 19 31 disabled 1 1 5 forwarding 2000 31 disabled 1 1 6 forwarding 19 31 disabled 1 1 7 forwarding 19 31 disabled 1 1 8 forwarding 19 31 disabled 1 1 9 forwarding 19 31 disabled 1 1 10 forwarding 19 31 disabled Poof The cost of 1000 is gone. As mentioned in the Port VLAN Priority Load Balancing section...

Example 76 Selecting Cat1CPort12 As the Preferred Path for VLAN 3 By Manually Specifying a Lower Cost on Port

Console> (enable) set spantree portvlancost 1 2 cost 14 3 Port 1 2 VLANs 12,4-1005 have path cost 19. Port 1 2 VLANs 3 have path cost 14. This lowers the cumulative Root Path Cost on Port 1 2 to 18 (14+4) and causes it to win out against the cost of 19 on Port 1 1. However, this approach might not be stable in the long run. What if the link between Cat-1A and Cat-1B is replaced with Fast Ethernet or Fast EtherChannel Or what if an additional switch is added in the middle of this link In fact,...

Example 86 Sample Router Configuration for 8021Q

Specify the interface to configure interface fastether 2 0.1 ip address 172.16.10.1 255.255.255.0 ipx network 100 encapsulation dot1q 200 The number at the end of the encapsulation statement specifies the VLAN number. The 802.1Q specification allows VLAN values between 0 and 4095 (with reserved VLAN values as discussed previously). However, a Catalyst supports VLAN values up to 1005. Generally, do not use values greater than 1005 when specifying the 802.1Q VLAN number to remain consistent with...

Example 915 LEC Cant Contact LES

ATM show lane client LE Client ATM0.1 ELAN name ELAN1 Admin up State initialState Client ID unassigned Next join attempt in 10 seconds Join Attempt 8 Last Fail Reason Control Direct VC being released HW Address 0010.2962.e430 Type ethernet Max Frame Size 1516 VLANID 1 ATM Address VCD rxFrames txFrames Type ATM Address 0 0 0 configure 0 0 0 direct 0 0 0 distribute 0 0 0 send 0 0 0 forward The output in Example 9-15 shows most of the same symptoms as the output in Example 9-14 however, the first...

Example A5 Sample Configuration for CatARSM for HandsOn

Hostname Cat-A-RSM interface Vlan1 ip address 10.1.1.252 255.255.255.0 no ip redirects standby 1 priority 101 standby 1 preempt standby 1 ip 10.1.1.254 interface Vlan2 ip address 10.1.2.252 255.255.255.0 no ip redirects standby preempt standby 2 ip 10.1.2.254 interface Vlan3 ip address 10.1.3.252 255.255.255.0 no ip redirects standby 3 priority 101 standby 3 preempt standby 3 ip 10.1.3.254 router rip network 10.0.0.0 no ip classless line con 0 line aux 0 line vty 0 4 login end 1 A network...

Existing Infrastructure

Your trunk choice might be limited to whatever technology you currently deploy in your network. If your Catalyst interfaces are Ethernet and Fast Ethernet, and your cabling is oriented around that, you probably elect to use some form of Ethernet for your trunk lines. The question becomes one, then, of how much bandwidth do you need to support your users. If your backbone infrastructure currently runs FDDI, you might not be able to do much with other trunk technologies without deploying some...

Facilitates Multiservice Traffic

One of the most touted benefits of ATM is its capability to simultaneously support voice, video, and data traffic over the same switching infrastructure. Cells play a large part in making this possible by allowing all types of traffic to be put in a single, ubiquitous container. Part of this multiservice benefit is derived from points already discussed. For example, one of the biggest challenges facing voice over IP is the large end-to-end latency present in most existing IP networks. The low...

FDDI Resiliency

FDDI probably has the quickest failover rate because its resiliency operates at Layer 1, the physical layer. FDDI operates in a dual counter-rotating ring topology. Each ring runs in the opposite direction of the other ring. If a cable breaks between Cat-A and Cat-B as in Figure 8-17, both Catalysts see the loss of optical signal and enter into a wrapped state. Data continues to flow between all components in the network in spite of the cable outage. The cutover time is extremely fast because...

Figure 101 A MultiELAN Network Data Flow

Load Balancing Data Flow

Each hop through a router introduces additional latency and consumes routing resources within each router. Some of the latency stems from the segmentation reassembly process. Another latency factor includes the route processing time to determine the next hop. This element can be less significant in routers that do hardware routing (as opposed to legacy software-based routers). The hop-by-hop approach was necessary when networks interconnected with shared media systems such as Ethernet. Physical...

Figure 102 MPOA Model

Note also the presence of LANE components. MPOA depends upon LANE for intraELAN communications. Communication between a Multiprotocol Client (MPC) and a Multiprotocol Server (MPS) occurs over an ELAN. Communication between adjacent Next Hop Servers (NHSs), another MPOA component discussed later in the section on Next Hop Resolution Protocol (NHRP), also occurs over ELANs. Finally, MPSs also communicate over ELANs. Additionally, if frames are sent between MPCs before a shortcut is established,...

Figure 103 Control Flow Sequence in an MPOA System

The message sequence occurs as follows 1. The ingress MPC sends an MPOA resolution request to the ingress MPS. 2. The ingress MPS translates the request into an NHRP request that gets forwarded toward the egress MPS. 3. The egress MPS issues an MPOA cache imposition request to the egress MPC. 4. The egress MPC responds back to the egress MPS with an MPOA cache imposition reply. 5. The egress MPS returns an NHRP resolution to the ingress MPS. 6. The ingress MPS sends an MPOA resolution reply to...

Figure 104 MPS Anatomy

The MPS has a set of interfaces attached to the ATM cloud and at least one interface for internal services. The external connections pointing to the ATM cloud consist of LANE client(s) and an MPS interface. The LANE clients support the MPOA device discovery protocol described later, and the actual flow of data before the shortcuts are established. The MPS also uses the LEC to forward resolution requests to the next NHS in the system. The service interface interacts with internal processes such...

Figure 105 MPOA Host Device Anatomy

Like the MPS, the MPC host device has internal and external interfaces. The external interfaces include the LEC and the MPC. The MPC communicates to the LES through the LEC to detect MPOA neighbors. Also, traffic transmissions that are initiated before a shortcut is established will pass through the LEC. The MPC interface, on the other hand, is used for shortcuts. When the MPC detects a flow, it issues a resolution request through its MPC interface. The MPC receives the resolution reply through...

Figure 107 MPOA Data Flow Summary

(1)Before the ingress MPC requests a shortcut, the MPC forwards frames through the LEC interface to the ATM cloud to the MPS. The MPS receives the flow on its LEC interface, performs routing and (2) forwards the frame to the next MPS. This continues until the frame reaches the egress MPS where the frame is forwarded (3) over the ELAN to the egress MPC. Until the ingress MPC establishes a shortcut, all frames pass through LECs at each device. When the ingress MPC detects a flow that exceeds the...

Figure 111 Routerona Stick Design

In this approach, traditional routers are connected via one or more links to a switched network. Figure 11-1 shows a single link, the stick, connecting the router to the rest of the campus network. Inter-VLAN traffic must cross the Layer 2 backbone to reach the router where it can move between VLANs. It then travels back to the desired end station using normal Layer 2 forwarding. This out to the router and back flow is characteristic of all router-on-a stick designs. Figure 11-1 portrays the...

Figure 1114 Each Catalyst Contains Only a Single VLAN

The results in Figure 11-14 are very similar to those in Figure 11-13. Cat-A sees the candidate packet, but only Cat-B sees the enable packet. Shortcut switching is not possible. MLS requires that the same NFFC or MSFC PFC must see the flow traveling to and from the router. This can require careful planning and design work in certain situations. However, simply placing both VLANs on both switches does not necessarily solve the problem. In Figure 11-15, both Cat-A and Cat-B contain the Red and...

Figure 1119 HostA Communicating with HostB via MLS

First, look at the case of Host-A sending traffic to Host-B. The traffic from Host-A to the router travels up the ISL links connecting the Catalysts and the router to each other. As the first packet hits the NFFC in each Catalyst, it is recognized as a candidate packet and three partial shortcut entries are created (one per Catalyst). As the packet travels back down from the router to reach Host-B, all three NFFC cards see the enable packet and complete the shortcut entries. However, as...

Figure 112 One LinkperVLAN

In this case, the switched network carries three VLANs Red, Blue, and Green. InterSwitch Link (ISL) trunks are used to connect the three switches together, allowing a single link to carry all three VLANs. However, connections to the router use a separate link for every VLAN. Figure 11-2 illustrates the use of 10 Mbps router ports however, Fast Ethernet, Gigabit Ethernet, or even other media such as Asynchronous Transfer Mode (ATM) or Fiber Distributed Data Interface (FDDI) can be used. There...

Figure 1123 A Large MLS Network

As you can see, the net effect is a huge, flat network with lots of routers sitting on the perimeter. The RSM and the MLS processing are not creating any Layer 3 barriers. The VLAN Trunking Protocol (VTP) discussed in Chapter 12, VLAN Trunking Protocol, automatically puts all 50 VLANs on all 50 switches by default (even if every switch only uses two or three VLANs). Every switch then starts running 50 instances of the Spanning-Tree Protocol. If a problem de velops in a single VLAN on a single...

Figure 1124 Using MLS to Create Layer 3 Partitions

In this case, VLANs have not been allowed to spread throughout the campus. Assume that that the campus represents two buildings. VLANs 1-10 have been contained with Building 1. VLANs 11-20 have been placed in Building 2. A pair of links connects the two buildings. Rather than simply creating ISL links that trunk all VLANs across to the other building, non-trunk links have been used. By placing each of these links in a unique VLAN, you are forcing the traffic to utilize Layer 3 switching before...

Figure 114 Sample MLS Network

This network consists of two VLANs, VLAN 1 (Red) and VLAN 2 (Blue). Two end stations have been shown. Host-A has been assigned to the Red VLAN, and Host-B has been assigned to the Blue VLAN. An ISL-attached router has also been included. Its single Fast Ethernet interface (Fast Ethernet1 0) has been logically partitioned into two subinterfaces, one per VLAN. The IP and MAC addresses for all devices and subinterfaces are shown. Figure 11-4 portrays the router as an ISL-attached external device...

Figure 117 Candidate Packet Fields

Poadcr Elhemel Hinder IF Heiidw Pflfiko Poadcr Elhemel Hinder IF Heiidw Pflfiko The ISL header contains a VLAN ID of 1. The Ethernet header contains a source MAC address equal to Host-A and a destination MAC address equal to 00-00-0C-11-11-11, the MAC address of subinterface 1 0.1 on the router. The source and destination IP addresses belong to Host-A and Host-B, respectively. The switch uses the destination MAC address to perform two actions It forwards the packet out Port 1 1 toward the...

Figure 12 Four Ethernet Frame Formats

The frame formats developed as the LAN industry evolved and differing requirements arose for protocols. When XEROX developed the original Ethernet (which was later adopted by the industry), a frame format like the Ethernet frame in Figure 1-2 was defined. The first 6 octets contain the destination's MAC address, whereas the next field of 6 octets contain the source's MAC address. Two bytes follow that indicate to the receiver the correct Layer 3 protocol to which the packet belongs. For...

Figure 1214 Flooding in a Multiple Domain Network

AW 1.3,3 A iivsVUANc 1,9,6 Actvo VI. AW 1.3,3 There are methods of controlling the distribution of flooded traffic throughout the network. These methods include the features of VTP pruning to control flooding, and modifications to the multicast behavior through Cisco Group Management Protocol (CGMP). VTP pruning is discussed in the section in this chapter, VTP Pruning Advanced Traffic Management. Details on controlling multicast with CGMP is described in Chapter 13,...

Figure 123 A Multiple VTP Domain Network

Whenever a Catalyst makes a VTP announcement, it includes the VTP domain name. If the receiving Catalyst belongs to a different management domain, it ignores the announcement. Therefore, VTP announcements from the wally domain on the left of the drawing are never seen by the Catalysts in the wally domain on the right of the drawing. If you are installing a domain border switch that connects two domains, it becomes a member of the management domain that it first hears from. Therefore, be sure to...

Figure 127 VTP Summary Advertisement Format

Each row in Figure 12-7 is four octets long. The Version, Type, Number of Subnet Advertisement Messages, and Domain Name Length Fields are all one octet long. Some of the fields can extend beyond four octets and are indicated in the figure. A description of each of the fields follows the decode in Figure 12-8. Figure 12-8 decodes a summary advertisement packet encapsulated in an ISL trunking protocol frame. If the trunk uses 802.1Q rather than ISL, the VTP message is exactly the same, only...

Figure 128 VTP Summary Advertisement Analyzer Decode

StiflSi -----ISL Protocol Packct ----- J ISL Destination Address OlOOUCOOOO S ISL Source Address 0DEQF7E D5D1 , ) IBL Constant value 0kAAAAD3 J IBL Virtual LAN ID (VLAN) 1 J ISL Dndsc Protocol Data Unit (PPDU) - I J. IBL Port Indes 1 J ETHER Destination Multicast OlGOOCCCOCCC -O ETHER Source Station GDE0F7E6DBFB JJ ETHER SO . 3 length - 63 Q ETHER LLC C > -AA S-AA , SNAP ID Cisco Tj pe 20Q3 (VTP) VTP -----Cisco Virtual Trunk Protocol (VTP) Packet----- nnbor ot Subset- Ad 'ort rv.es Length a...

Figure 129 VTP Subset Advertisement Format

The VLAN-info Field Contains Information for Each VLAN and is Formatted as Follows V LAN-name (Padded with zeros to Multiple of 4 Bytes) The summary advertisement has a Seq-Number field in the header indicating the number of subset advertisements that follow. If you have a long VLAN list, VTP might need to send the entire list over multiple subset advertisements. Figure 12-10 shows a subset advertisement (partial listing). As with the summary advertisement, the message includes the VTP version...

Figure 13 A Worst Case Collision Example

Ethernet rules state that a station must detect and report collisions between the furthest points in the network before the source completes its frame transmission. Specifically, for a legacy 10 Mbps Ethernet, this must all occur within 51.2 microseconds. Why 51.2 microseconds The time is based on the smallest frame size for Ethernet, which corresponds to the smallest time window to detect and report collisions. The minimum frame size for Ethernet is 64 bytes, which has 512 bits. Each bit time...

Figure 1310 Switches and Multicast Traffic

When the router sends a general membership query, it uses the MAC multicast address 01 -00-5E-00-00-01. This multicast address forces the switch to send the frame to all ports. When a host responds to the query with a report, the report goes to all ports. Clearly, though, it would be nice to restrict the distribution of multicast frames in the switched network to only those hosts that really want the traffic. In a Catalyst, you have three potential ways of limiting the multicast scope static...

Figure 1311 CGMP Operation Example

In Figure 13-11, a Cisco router receives IGMP membership reports from PC-1 and PC-2. The router sends a CGMP configuration message to the Catalyst telling it about the source MAC address of the host and the multicast group from which it wants to receive traffic. For example, PC-1 asks to join 224.1.10.10. The router tells the Catalyst to send multicast traffic with the destination MAC address of 01-00-5E-01-0A-0A to the host with the source MAC address 00-60-08-93-DB-C1. The Catalyst searches...

Figure 1314 A Detailed CGMP Exchange

GDA1 01-00- 5E-01-OA-OA USA1 00-60-08-93-DB-C1 PC-1 wants to join multicast group 224.1.10.10. It sends an IGMP membership report informing routers that it wants to see these frames. The router creates a CGMP join message with a GDA of 01-00-5E-01-0A-0A and a USA with PC-1's source address. The router sends the frame as a CGMP multicast (01 -00-0C-DD-DD-DD). The Catalyst detects the CGMP join message, looks in its bridge table for the host, adds the GDA to the port bridge table, and starts to...

Figure 132 IGMP Version 1 Frame Format

The first field of the frame indicates what version of IGMP generated the frame. For version 1, this value must be 1. The next field specifies the message type. Version 1 defines two messages a host membership query and a host membership report. The Checksum field carries the checksum computed by the source. The receiving device examines the checksum value to determine if the frame was corrupt during transmission. If the checksum value doesn't match, the receiver discards the frame. The source...

Figure 137 An IGMP Version 2 Leave Demonstrated

The router currently forwards frames for both groups on the segment. The host currently subscribed to 224.2.20.20 decides that it no longer wants to receive the multicast stream for this group, so it transmits a leave message. The router receives this message and checks its multicast table to see if there are any other hosts on the segment that want the stream. In this example, there are no other hosts in the group. The router sends a group specific query message to the group 224.2.20.20 to...