09-20-2021 07:47 AM
I need your help as by default cisco switches have only 3 modes (pvst+ ,pvst ,MST) and i have more than 200 vlans per switch when i configured the below spanning-tree it shows no spanning-tree on some vlans although i need to be enabled for all of the, same happened on all other switches and when i tried to
#show spanning-tree vlan 198
#Spanning tree instance(s) for vlan 198 does not exist.
spanning-tree mode rapid-pvst
spanning-tree extend system-id
no spanning-tree vlan 198-201,789-790,831,930,932-933
spanning-tree vlan 2-4094 priority 28672
Is there any workaround for this
09-20-2021 07:55 AM
Spanning tree instance(s) for vlan 198 does not exist
Make sure VLAN 198 actually exists on the switch, if not, created it and then try the command again.
config t
vlan 198
description a test vlan
exit
show spanning-tree vlan 198
HTH
09-20-2021 08:37 AM
I did that and it's exist but not included in spanning tree
09-20-2021 09:06 AM
Can you post the output of "show vlan"?
HTH
09-20-2021 09:42 AM
according to the config snippet in your post, this is normal as you have told the switch to NOT run spanning tree on vlan 198
09-20-2021 10:37 AM
09-20-2021 11:25 AM
the line
spanning-tree vlan 2-4094 priority 28672
is only setting the priority for these vlans if they exist and are keeping a tree
the line right above that
no spanning-tree vlan 198-201,789-790,831,930,932-933
says don't keep a tree for these vlans
09-20-2021 12:11 PM
09-20-2021 12:40 PM
Hello
What type of switches are your running, As with that amount of vlans its possible you may have exceeded your vlan or logical stp virtual port limitation!
sh ver
sh vlan brief
sh spanning-tree summary total
09-20-2021 02:03 PM
#show version
Switch Ports Model SW Version SW Image Mode
------ ----- ----- ---------- ---------- ----
* 1 52 WS-C3650-48TD 03.06.04.E cat3k_caa-universalk9 INSTALL
Also i have cisco 9300 series and the same issue as all the models for cisco switches no longer support more than 3 modes for STP
#show vlan brief \\ i have more than 200 due to my environment needed and spanning-tree is running on most of them and not the others up to 128 only as per instance.
#show spanning-tree summary totals
Switch is in pvst mode
Root bridge for: VLAN0012, VLAN0030
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
EtherChannel misconfig guard is enabled
UplinkFast is disabled
BackboneFast is disabled
Configured Pathcost method used is short
Name Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
128 vlans 0 0 0 258 258
09-20-2021 04:23 PM - edited 09-20-2021 04:24 PM
Hello
The reason why its not showing is youve disabled spanning-tree for vlan 198 also other vlans, its need to be enabled and either allowed over the trunk or assigned to an active access-port for it to show active
@Eng_manar88 wrote:
the line
spanning-tree vlan 2-4094 priority 28672 <-- this justs provides an stp priority to vlans it doesnt make them active
is only setting the priority for these vlans if they exist and are keeping a tree
the line right above that
no spanning-tree vlan 198-201,789-790,831,930,932-933 <- stp for these vlans is disabled
says don't keep a tree for these vlans
Name Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
128 vlans 0 0 0 258 258
looks like you have 128 vlans with 2x trunks and maybe 2 x non trunking ports on this switch totalling 258 active logical stp instances
09-21-2021 04:06 AM
no spanning-tree vlan 198-201,789-790,831,930,932-933
Again, I didn't place that configuration it has been done by the switch itself.Also i configured not only the priority but also
spanning-tree vlan 2-4094 root-primary ----> per root switch and similarly on the secondary switch but it will not show on the running configuration.
Meanwhile i have many trunk ports some of them allow specific vlans and others 4 links must pass the trunks as simple as the below topology
03-06-2022 10:01 AM
Hi,
there is actually a limit for the maximum number of spanning-tree instance the switch can run on PVST+ or rapid-PVST+.
For example on some platforms you can't exceed the amount of 128 vlan spanning-tree instances (3560, 3750, 3850...)
Beyond that, vlans can still be created, but without any spanning-tree protection. Beware of the loops then
C.
08-31-2023 09:52 AM
IF YOU issue #spanning-tree Vlan X BUT the Vlan instance doesn't exist
====>>> the simple fix to this issue is that all the interconnected switches must be in a trunk mode
09-01-2023 03:20 AM
The Catalyst 3650 has a limit of 128 STP instances when in Rapid PVST+ mode.
You can create more than 128 VLANs, however STP won't run on any over 128 when in Rapid PVST+ mode.
Why do you need so many VLANs on a C3650?
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