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Chapter 5
Using Spanning Tree with VLANs
Bridge Max Age 10 sec Hello Time 2 sec Forward Delay 7 sec
Port Vlan Port-State Cost Priority Fast-Start
--------- ---- ------------- ----- -------- ----------
1/1 1 forwarding 19 32 disabled
1/2 1 forwarding 19 32 disabled
2/1 1 not-connected 100 32 disabled
2/2 1 not-connected 100 32 disabled
2/3 1 not-connected 100 32 disabled
2/4 1 not-connected 100 32 disabled
2/5 1 not-connected 100 32 disabled
--More--
Notice that the bridge IP priority is set to 8192; the designated root and
bridge IP MAC ADDR is the same because this is the root bridge. The Port-
States are both 19, which is the default for 100Mbps. Because both ports are
in forwarding state, the 1900 switch must have one of its FastEthernet ports in
blocking mode. Let's take a look by using the show spantree command on
the 1900 CLI:
Port FastEthernet 0/26 of VLAN1 is Blocking
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 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 1, path cost 0
Timers: message age 10, forward delay 7, hold 1
Notice that port f0/26 is in blocking mode and port f0/27 is in forwarding
mode. If we want port f0/26 to be in forwarding mode and f0/27 in blocking
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