%SPANTREE_VLAN_SW-2-MAX_INSTANCE

[mahesh18]

                   Hi Everyone,

On 3550 switch i see logs below

%SPANTREE_VLAN_SW-2-MAX_INSTANCE: Platform limit of 128 STP instances exceeded. No instance created for VLAN95 (port Gi0/1).

Need to  know what does this log mean?

Regards

Mahesh

[Rolf Fischer · Accepted solution]

Hi Mahesh,

there's a platform limitation of  max 128 Spanning-Tree instances for the 2k and 3k platforms.

When you create more than 128 VLANs (e.g. on a 4k or 6k which is the VTP server), the new VLANs are created but there is no spanning-tree instance for this VLANs on those platforms. Without manual pruning the uplink-ports (switchport trunk allowed vlan ) there's a serious risk of a bridging-loop!

System Message Guide

Best Regards

Rolf

[Rolf Fischer · Accepted solution]

Here are two similar discussions which give very detailed explanation:

https://supportforums.cisco.com/thread/2132702

https://supportforums.cisco.com/thread/2047402

Hope that helps

Rolf