04-16-2007 01:28 AM - edited 03-05-2019 03:28 PM
Hi,
I thought priority for building Bridge ID within STP defaults to 32,768.
I have created 4 vlans, and the default priority for vlan 2 and 3 for example is: 32770 and 32771. Why is not the default one? The switch is with its default config.
Thanks in advance.
Jorge
Solved! Go to Solution.
04-16-2007 01:57 AM
Hi Jorge
This is probably because you have spanning-tree system extend-id turned on.
Taken from one of our switches :-
HQ-FTZ-F00-SW1#sh spanning-tree vlan 30
VLAN0030
Spanning tree enabled protocol ieee
Root ID Priority 32798
Address 000a.b8b3.a980
Cost 19
Port 24 (FastEthernet0/24)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32798 (priority 32768 sys-id-ext 30)
Address 000e.84e1.f680
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/16 Desg FWD 19 128.16 Edge P2p
Fa0/17 Desg FWD 19 128.17 Edge P2p
Fa0/24 Root FWD 19 128.24 P2p
This switch has "spanning-tree system extend-id" turned on. This output is for vlan 30 and the priority is
32768 + 30 = 32798.
So in your case
32768 + 2 = 32770
32768 + 3 = 32771
HTH
Jon
04-16-2007 01:57 AM
Hi Jorge
This is probably because you have spanning-tree system extend-id turned on.
Taken from one of our switches :-
HQ-FTZ-F00-SW1#sh spanning-tree vlan 30
VLAN0030
Spanning tree enabled protocol ieee
Root ID Priority 32798
Address 000a.b8b3.a980
Cost 19
Port 24 (FastEthernet0/24)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32798 (priority 32768 sys-id-ext 30)
Address 000e.84e1.f680
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/16 Desg FWD 19 128.16 Edge P2p
Fa0/17 Desg FWD 19 128.17 Edge P2p
Fa0/24 Root FWD 19 128.24 P2p
This switch has "spanning-tree system extend-id" turned on. This output is for vlan 30 and the priority is
32768 + 30 = 32798.
So in your case
32768 + 2 = 32770
32768 + 3 = 32771
HTH
Jon
04-16-2007 02:15 AM
Thanks a lot Jon, I had it turned on, but as it is the defautl config, I didnt realize about it.
didnt know about it.
Best regards,
Jorge
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