In Cisco 3550 configuration guide, I have found that maximum spanning tree supported instances are 128. What if you got above 128 VLANS and using default PVST.
Cisco quote "Note: The switch supports up to 128 spanning-tree instances." I guess that if you are going to use more than 128 VLANs you might need to use MST so that you can have multiple VLANs in single spanning tree instance. Regards, Masood Ahmad Shah BLOG: http://www.weblogs.com.pk/jahil/
