BROCADE IP PRIMER

SummaryWe need to define this on both switches. For Core Switch A:CoreSwitchA(config)#vlan 10CoreSwitchA(config-vlan-10)#vsrp vrid 1CoreSwitchA(config-vlan-10-vrid-1)#backupCoreSwitchA(config-vlan-10-vrid-1)#enableWe arbitrarily chose a VRID of 1. Notice that we defined Core Switch A as“backup.” All switches participating in the same VRID must be defined asBackups. The election will promote the one switch to Master. Finally, weenabled VSRP. Now, for this to function, we must configure Core Switch B aswell:CoreSwitchB(config)#vlan 10CoreSwitchB(config-vlan-10)#vsrp vrid 1CoreSwitchB(config-vlan-10-vrid-1)#backupCoreSwitchB(config-vlan-10-vrid-1)#enableNow an election will be held, Core Switch A will be declared Master (let's say),and the design will continue as we've illustrated earlier in the Chapter. LikeSTP, this is an active/standby configuration. One is active. The others are inactive.VSRP is simply another method to provide redundancy to your networkinfrastructure.Summary• Spanning Tree Protocol prevents Layer 2 loops• A Layer 2 loop may cause a broadcast storm, which will cause theswitches' CPUs to be overwhelmed• Spanning Tree Protocol is defined in IEEE 802.1d• Spanning Tree Protocol uses BPDU frames to discover loops andexchange information• An election decides which switch is the root switch• The root switch interfaces are never in “Blocking” state• Configuring a switch's priority allows the engineer to manipulate theelection• IEEE 802.1d Spanning Tree goes through four states before the interfacemay pass traffic:— Blocking - preventing all traffic, aside from BPDUs— Listening - listening for BPDUs returning (indicating a loop); this takes15 seconds— Learning - learning the Layer 2 infrastructure including MACaddresses and the root switch; this takes 15 seconds— Forwarding/Blocking - allowing (or preventing) traffic based on theresult of the first three statesBrocade IP Primer 213