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Chapter 5
Using Spanning Tree with VLANs
1/1 1005 not-connected 10 4 disabled
Todd5000> (enable) sh spantree 1/2
Port Vlan Port-State Cost Priority Fast-Start
--------- ---- ------------- ----- -------- ----------
1/2 1 forwarding 19 32 disabled
1/2 2 forwarding 19 32 disabled
1/2 3 forwarding 19 16 disabled
1/2 4 forwarding 19 16 disabled
1/2 1003 not-connected 19 32 disabled
1/2 1005 not-connected 19 4 disabled
Todd5000> (enable)
We want to set the VLAN port priority on the 1900 switch now. Notice
in the following switch output that f0/26 is in forwarding mode and f0/27 is
blocking. Remember that we changed the port cost to 20 for f0/27, which
makes port f0/26 more desirable to the switch:
Port FastEthernet 0/26 of VLAN1 is Forwarding
Port path cost 10, Port priority 128
Designated root has priority 8192, address
00E0.3488.FC00
Designated bridge has priority 8192, address
00E0.3488.FC00
Designated port is 2, path cost 0
Timers: message age 10, forward delay 7, hold 1
Port FastEthernet 0/27 of VLAN1 is Blocking
Port path cost 20, Port priority 128
Designated root has priority 8192, address
00E0.3488.FC00
Designated bridge has priority 8192, address
00E0.3488.FC00
Designated port is 1, path cost 0
Timers: message age 10, forward delay 7, hold 1
You can change the priority of the port, but not the VLAN priority as you
can with the 5000 series switch. The command is spantree priority:
1900A#config t
1900A(config-if)#int f0/27
1900A(config-if)#spantree priority 16
1900A(config-if)#
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