Spanning-Tree instance does not exist for active vlan

dcheney4133 · ‎07-17-2017

Vlan 72. It exists on the switch and is active, but there are no spanning-tree instances for it. It's HSRP brother has an instance for spanning-tree on vlan 72 and seems to be working fine. It makes no sense to me, hoping someone can help!

CHS-MDF-3850A#show spanning-tree vlan 72

Spanning tree instance(s) for vlan 72 does not exist.

CHS-MDF-3850A#
CHS-MDF-3850A#
CHS-MDF-3850A#show vlan bri

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Gi1/0/10, Gi1/0/11, Gi1/0/13, Gi1/0/14, Gi1/0/15, Gi1/0/16
Gi1/0/17, Gi1/0/18
20 VoIP active
30 Printer active
40 Server active Gi1/0/12
50 Cameras active
60 APs active
64 Wireless-Hidden active
72 Wireless-Staff active

------------------------------------------------------------------------------------------------

On the HSRP brother:

CHS-MDF-3850B#show spanning-tree vlan 72

VLAN0072
Spanning tree enabled protocol rstp
Root ID Priority 28744
Address 204c.9e22.8400
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 28744 (priority 28672 sys-id-ext 72)
Address 204c.9e22.8400
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/1 Desg FWD 4 128.1 P2p
Gi1/0/3 Desg FWD 4 128.3 P2p
Gi1/0/5 Desg FWD 4 128.5 P2p
Gi1/0/6 Desg FWD 4 128.6 P2p
Gi1/0/7 Desg FWD 4 128.7 P2p
Gi1/0/8 Desg FWD 4 128.8 P2p
Gi1/0/9 Desg FWD 4 128.9 P2p
Po1 Desg FWD 3 128.2027 P2p Peer(STP) *****This is the switch that doesn't have an instance for vlan 72

CHS-MDF-3850B#show vlan bri

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Gi1/0/2, Gi1/0/4, Gi1/0/10, Gi1/0/11, Gi1/0/12, Gi1/0/13, Gi1/0/14
Gi1/0/15, Gi1/0/16, Gi1/0/17, Gi1/0/18
20 VoIP active
30 Printer active
40 Server active
50 Cameras active
60 APs active
64 Wireless-Hidden active
72 Wireless-Staff active

GRANT3779 · ‎07-17-2017

On the switch that doesn't have the instance -

Do you have a trunk port with that vlan allowed on it or an actual port in up/up state and placed in that vlan?

What is the output from

show interfaces trunk

As an example from one of my own switches -

show interfaces trunk

Port Mode Encapsulation Status Native vlan
Gi0/7 on 802.1q trunking 998
Gi0/8 on 802.1q trunking 998

Port Vlans allowed on trunk
Gi0/7 500,502,600,780-781
Gi0/8 1-4094

Port Vlans allowed and active in management domain
Gi0/7 500,502,600,780-781
Gi0/8 1,70,500,502,600,780-781,971-972

Port Vlans in spanning tree forwarding state and not pruned
Gi0/7 500,502,600,780-781
Gi0/8 1,70,500,502,600,780-781,971-972

I believe you need to have a port in an up/up state for that vlan, whether that be an access port or trunk port allowing that vlan.

MAHRISH · ‎10-30-2019

Hello, I have the same problem. When I issued "Show spanning-tree" it came up with the same result, "No spanning-tree instances exist." I'm sure that I have VLAN assigned and the status of the ports is up/up. (This is a packet tracer project)

As you mentioned above to issue "show interfaces trunk" I did and nothing came up but when I issue the show interface on the other switches I do see the results of the trunked interfaces and VLANs section. What could the problem be? Is it the packet tracer issue or maybe, there is something that I forgot.

Note: All the Switches are configured the same way.