Spanning tree instance for vlan xxx does not exist

[sadqazi]

Hello,

The 3750 series Catalyst switch in our lab has five ports that are up and four of them are in forwarding state with their LED lights blinking green. One port (Gi1/0/7) is blinking amber and is not forwarding although it is up. Output for sh ip int br

Switch#sh ip int br
Interface              IP-Address      OK? Method Status                Protocol
Vlan1                  unassigned      YES NVRAM  up                    down
FastEthernet0          unassigned      YES NVRAM  down                  down
GigabitEthernet1/0/1   unassigned      YES unset  up                    up
GigabitEthernet1/0/2   unassigned      YES unset  up                    up
GigabitEthernet1/0/3   unassigned      YES unset  up                    up
GigabitEthernet1/0/4   unassigned      YES unset  up                    up
GigabitEthernet1/0/5   unassigned      YES unset  down                  down
GigabitEthernet1/0/6   unassigned      YES unset  down                  down
GigabitEthernet1/0/7   unassigned      YES unset  up                    up
GigabitEthernet1/0/8   unassigned      YES unset  down                  down
GigabitEthernet1/0/9   unassigned      YES unset  down                  down
GigabitEthernet1/0/10  unassigned      YES unset  down                  down
GigabitEthernet1/0/11  unassigned      YES unset  down                  down

Gi1/0/1, 1/0/2, 1/0/3, and 1/0/4 are up and connected. Gi1/0/7 is up but is not working and has blinking amber light. I read that blinking light most probably means STP blocking. When I checked STP status for vlan 105 (which is for Gi1/0/7), here is what I got:

Switch#show spanning-tree vlan 105

Spanning tree instance(s) for vlan 105 does not exist.

where as for the working vlans, it gives me:

Switch#show spanning-tree vlan 103

VLAN0103
  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     xxxx.xxxx.xxxx
             Cost        8
             Port        3 (GigabitEthernet1/0/3)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32871  (priority 32768 sys-id-ext 103)
             Address     xxxx.xxxx.xxxx
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Doing sh vlan and sh spanning-tree summary gives the output:

Switch#sh vlan

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Gi1/0/18, Gi1/0/19, Gi1/0/20
                                                Gi1/0/21, Gi1/0/22, Gi1/0/23
103  VLAN0103                         active    Gi1/0/3
119  VLAN0119                         active    Gi1/0/4
120  VLAN0120                         active    Gi1/0/1
127  VLAN0127                         active    Gi1/0/2
1002 fddi-default                     act/unsup
1003 trcrf-default                    act/unsup
1004 fddinet-default                  act/unsup
1005 trbrf-default                    act/unsup

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
1    enet  100001     1500  -      -      -        -    -        0      0
103  enet  100103     1500  -      -      -        -    -        0      0
119  enet  100119     1500  -      -      -        -    -        0      0
120  enet  100120     1500  -      -      -        -    -        0      0
127  enet  100127     1500  -      -      -        -    -        0      0
1002 fddi  101002     1500  -      -      -        -    -        0      0
1003 trcrf 101003     4472  1005   3276   -        -    srb      0      0

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
1004 fdnet 101004     1500  -      -      -        ieee -        0      0
1005 trbrf 101005     4472  -      -      15       ibm  -        0      0

VLAN AREHops STEHops Backup CRF
---- ------- ------- ----------
1003 7       7       off

Remote SPAN VLANs
------------------------------------------------------------------------------

Primary Secondary Type              Ports
------- --------- ----------------- ------------------------------------------

Switch#sh spanning-tree summary
Switch is in pvst mode
Root bridge for: none
EtherChannel misconfig guard is enabled
Extended system ID           is enabled
Portfast Default             is disabled
PortFast BPDU Guard Default  is disabled
Portfast BPDU Filter Default is disabled
Loopguard Default            is disabled
UplinkFast                   is disabled
BackboneFast                 is disabled
Configured Pathcost method used is short

Name                   Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0103                     0         0        0          2          2
VLAN0119                     0         0        0          2          2
VLAN0120                     0         0        0          2          2
VLAN0127                     0         0        0          2          2
---------------------- -------- --------- -------- ---------- ----------
4 vlans                      0         0        0          8          8
Switch#

As it can be seen only the vlans that are connected to the network are the ones being shown here. My question is how do I get the vlan 105 to be in the Forwarding state? I tried

Switch(config)#spanning-tree vlan 105
Switch(config)#end

but that didn't fix the issue. Any help would be appreciated. 

Thank you.

[Peter Paluch · Accepted solution]

Hi,

According to the show vlan output, VLAN 105 is not created. Thus, no STP instance can be started for it.

Simply create the VLAN 105 - this should hopefully solve the issue.

Best regards,
Peter

[sadqazi]

Hi Peter,

Creating the Vlan worked. Although the Vlans were being shown in the config, when I re created the Vlan, it came up.

Thank you so much.

Best,

Sadaf.

[SoumenBhattacharjee2845]

---

I am facing a problem in 7k Nexus..... New created vlan 4 is not taking part of spanning tree as showing spanning tree instance does not exist for the vlan...... In show vlan it's exist and port also trunk..... Need assistance if I am doing something wrong

[ehayric1320]

I am seeing this same issue on a switch but the vlans are there...

Switch#sh spanning-tree vlan 21

Spanning tree instance(s) for vlan 21 does not exist.

Switch#sh vlan br
21 PRTG_VMHOSTS_10.X.X.X/29 active

[Giuseppe Larosa]

Hello @ehayric1320 ,

how many VLANs are defined in the VLAN database ?

what model of switch is this device ?

There are some low end switches that have a limited number of concurrent STP instances that can run on them like 64 or 128.

use

show spanning-tree summary t

o check how many VLANs have an STP instance and compare it with show vlan output .

you are likely using PVST+ or Rapid PVST

Hope to help

Giuseppe

[MHM Cisco World]

Make new post it better 

MHM

[ehayric1320]

So I think the issue may be that the VLANs are being pruned (blocked with 'trunk allowed' statements).

It's the only thing that makes sense. This is Rapid-PVST on a 6500 switch.