From: Pang Alan (alanpang2002@hotmail.com)
Date: Fri Dec 27 2002 - 23:45:00 GMT-3
Hi Group,
When I set the vlan priority to 0, the priority changes to 2. If I view the
priority from another switch, the priority is also 2.
The following is the related config and show commands. I see the line
Bridge ID Priority 2 (priority 0 sys-id-ext 2)
It just like the extended system id is added to the priority.
However, you can see that I have no extended vlans.
The questions:
1.Why the priority is different from the config and how to correct it?
2.How is the sys-id-ext derived?
Thank you very much.
Regards,
Alan
c3550#sh run
!
hostname c3550
!
enable secret level 14 5 $1$dpBd$QoyMzvsI6NkcSmji.tUO31
enable secret 5 $1$1J29$9XO/XWKVgjs3T11T0llap0
!
!
spanning-tree extend system-id
spanning-tree vlan 2 priority 0
!
!
c3550#sh span root
Root Hello Max Fwd
Vlan Root ID Cost Time Age Dly Root Port
---------------- -------------------- --------- ----- --- --- ------------
VLAN0001 32768 0004.c13b.0100 19 2 20 15 Fa0/10
VLAN0002 2 0009.b7e1.6b80 0 2 20 15
VLAN0003 32771 0009.b7e1.6b80 0 2 20 15
VLAN0068 32768 0004.c13b.0102 19 2 20 15 Fa0/10
VLAN0814 32768 0004.c13b.0103 19 2 20 15 Fa0/10
c3550#sh span vlan 2
VLAN0002
Spanning tree enabled protocol ieee
Root ID Priority 2
Address 0009.b7e1.6b80
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 2 (priority 0 sys-id-ext 2)
Address 0009.b7e1.6b80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Port ID Designated Port
ID
Name Prio.Nbr Cost Sts Cost Bridge ID
Prio.Nbr
---------------- -------- --------- --- --------- --------------------
--------
Fa0/10 128.10 19 FWD 0 2 0009.b7e1.6b80
128.10
Try to view the priority from another switch.
cat3500#sh span vlan 2
Spanning tree 2 is executing the IEEE compatible Spanning Tree protocol
Bridge Identifier has priority 20480, address 0004.c13b.0101
Configured hello time 2, max age 20, forward delay 15
Current root has priority 2, address 0009.b7e1.6b80
Root port is 23, cost of root path is 19
Topology change flag not set, detected flag not set, changes 6
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0
Interface Fa0/10 (port 23) in Spanning tree 2 is FORWARDING
Port path cost 19, Port priority 127
Designated root has priority 2, address 0009.b7e1.6b80
Designated bridge has priority 2, address 0009.b7e1.6b80
Designated port is 10, path cost 0
Timers: message age 1, forward delay 0, hold 0
BPDU: sent 19435, received 666
cat3500#?
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