08-03-2010 03:26 AM - edited 03-06-2019 12:17 PM
Hi,
I white the command on Switch 1 is Primary root bridgeVLAN 10 and Secondary root bridge 1001.
But now problem is both VLAN is show "This bridge is the root" but not showing the primary or secondary.
I know I have to concentrate on BID and RID value so escape this, how I can see which primary and secondary by another method.
!
spanning-tree vlan 1001 priority 28672
spanning-tree vlan 10 priority 4096
!
SW1#sh spanning-tree
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 000a.4152.b880
Cost 19
Port 48 (FastEthernet0/48)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 000a.f41a.5180
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/48 Root FWD 19 128.48 P2p
VLAN0010
Spanning tree enabled protocol ieee
Root ID Priority 4106
Address 000a.f41a.5180
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 4106 (priority 4096 sys-id-ext 10)
Address 000a.f41a.5180
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/48 Desg FWD 19 128.48 P2p
VLAN1001
Spanning tree enabled protocol ieee
Root ID Priority 29673
Address 000a.f41a.5180
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 29673 (priority 28672 sys-id-ext 1001)
Address 000a.f41a.5180
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/48 Desg FWD 19 128.48 P2p
Solved! Go to Solution.
08-03-2010 08:38 AM
Sorry just 'show spanning-tree root' you should get something like this ===>
Switch#sh spanning-tree root
Root Hello Max Fwd
Vlan Root ID Cost Time Age Dly Root Port
---------------- -------------------- --------- ----- --- --- ------------
VLAN0001 4097 000e.8338.0100 0 2 20 15
VLAN0019 4115 000e.8338.0100 0 2 20 15
VLAN0020 4116 000e.8338.0100 0 2 20 15
VLAN0021 4117 000e.8338.0100 0 2 20 15
VLAN0022 4118 000e.8338.0100 0 2 20 15
VLAN0023 4119 000e.8338.0100 0 2 20 15
VLAN0254 33022 0008.21b2.b300 23 2 20 15 Gi0/12
VLAN0994 33762 0008.21b2.b300 23 2 20 15 Gi0/12
Regards.
08-03-2010 06:26 AM
What is priority for VLANs 10 and 1001 on another switches?
08-03-2010 06:32 AM
lets consider I am using only one switch
!
spanning-tree vlan 1001 priority 28672
spanning-tree vlan 10 priority 4096
!
08-03-2010 06:34 AM
If have only one switch, it is a root for all VLANs.
08-03-2010 06:59 AM
Hello Abhinay,
From a Cisco switch If you want to have a summarized view of who is root for each vlan => show spanning-tree root will give a clear view of the Root bridge ID per vlan.
About secondary root, there is no way to query or listen to the network to find another potential secondary root simply because there are no advertisements or elections of secondary root bridges (only for the root).
==> Indeed in the BPDU configuration message content there is a "Root Bridge ID" field (which is exchanged and known by every switch participating in the STP instances) which identifies who is the root for each vlan, but there is no 'secondary root bridge ID' or any relative field.
As you may know for the command : " spanning-tree vlan vlan-id root {primary | secondary} [diameter diameter] " is a macro command that executes several other commands.
=> This command logic applies when the configuration command is executed; it does not dynamically change the priority if another switch later advertises a better priority.
Hope it helps.
Kind regards.
Karim
08-03-2010 08:34 AM
SW1#sh spanning-tree vlan 1 root ?
address Mac address of the root bridge
cost Path cost from this bridge to the root
detail Detailed of the status and configuration
forward-time Forward delay interval for the spanning tree topology
hello-time Hello time for the spanning tree topology
id Spanning tree root bridge identifier
max-age Max age for the spanning tree topology
port Root port
priority Bridge priority of the root bridge
| Output modifiers
after SW1#sh spanning-tree vlan 1 root no command support.
08-03-2010 08:38 AM
Sorry just 'show spanning-tree root' you should get something like this ===>
Switch#sh spanning-tree root
Root Hello Max Fwd
Vlan Root ID Cost Time Age Dly Root Port
---------------- -------------------- --------- ----- --- --- ------------
VLAN0001 4097 000e.8338.0100 0 2 20 15
VLAN0019 4115 000e.8338.0100 0 2 20 15
VLAN0020 4116 000e.8338.0100 0 2 20 15
VLAN0021 4117 000e.8338.0100 0 2 20 15
VLAN0022 4118 000e.8338.0100 0 2 20 15
VLAN0023 4119 000e.8338.0100 0 2 20 15
VLAN0254 33022 0008.21b2.b300 23 2 20 15 Gi0/12
VLAN0994 33762 0008.21b2.b300 23 2 20 15 Gi0/12
Regards.
08-03-2010 10:53 AM
heyyy Thanks...
I didn't get exact answer but it's ok coz root bridge cost is always 0 and others are different depend on topology.
then we can trace how many 0 cost of vlan and in between we can see which is primary and secondary.
Thanks once...
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide