BROCADE IP PRIMER

IEEE 802.1s (MST)another instance of Spanning Tree (in a different VLAN). In fact, you can mixand match further. For example, one VLAN's Spanning Tree may be using802.1d. Another VLAN's Spanning Tree may be using 802.1w.You will hear MST sometimes referred to as Per VLAN Spanning Tree (PVST).PVST is a predecessor to what has evolved into IEEE 802.1s.There is nothing to consciously configure to “enable” 802.1s. It's there for youto use. All you need to do is define it at the VLAN config level:Switch(config)#vlan 10Switch(config-vlan-10)#spanning-treeYou could also configure 802.1w:Switch(config-vlan-10)#spanning-tree 802-1wYou can configure your switch's priority, as it pertains to your VLAN's SpanningTree:Switch(config-vlan-10)#spanning-tree priority 10You can adjust timers (again, unique to your VLAN's Spanning Tree):Switch(config-vlan-10)#spanning-tree max-age 15If you're using RSTP, you can define ports as “admin-pt2pt-mac” or “adminedge-port”:Switch(config-vlan-10)#spanning-tree 802-1w e 9 admin-pt2ptmacSwitch(config-vlan-10)#spanning-tree 802-1w e 15 admin-edgeportOr, if you prefer, you can disable Spanning Tree all together, for your particularVLAN:Switch(config-vlan-10)#no spanning-treeThe important thing to remember is that all of these commands are beingissued within the Vlan Config mode. It's your own global Spanning Tree encapsulatedin your VLAN. You can do anything with it that you would normally havedone on the global level.STP Load SharingLet's say you have four switches fully meshed. Let's say you are running atleast two VLANs on all four of these switches. If we left the Spanning Tree electionsto their natural state, both VLANs would most likely choose the samelinks to be in Forwarding and Blocking.Brocade IP Primer 209