Tuesday, June 9, 2009

Cisco Lab 2 : Spanning-tree

1. Spanning tree protocol (STP)
2. Root bridge and port election
3. Rapid STP (RSTP)

Spanning Tree Protocol (STP)
1. Show STP
switch#show spanning-tree
- Root bridge has lowest bridge ID (bridge priority+MAC address)
- All ports of root bridge is designated port
- Root port is the port with the lowest path cost or lowest port ID (port priority+port number) to the root bridge

Root bridge and port election
1. Changing bridge priority
switch#spanning-tree vlan "vlan number" priority "possible priority number"
switch#spanning-tree vlan "vlan number" root primary --> bridge priority=24586
2. Changing default path cost
switch(config-if)#spanning-tree vlan "vlan number" cost "path cost number"
3. Changing port ID
switch(config-if)#spanning-tree vlan "vlan number" port-priority "port priority number"

Rapid spanning tree (RSTP)
1. Enable RSTP
switch(config)#spanning-tree mode rapid-pvst

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