Add VLAN to trunk causes switch to drop

[Terren_Crider]

Hi all, I've got two switches separated by about 7 miles of fiber and an Internet link at each site. I need a certain number of VLANs to extend between the sites for HA purposes. VLANs: tagged 243, 923-925, 927, 1000, untagged 4040 All of these VLANs span the trunk no problem except for 927. When I apply 927 the distant switch drops. When I remove 927, it comes back. Spantree is applied and enabled at the HA site, but not the main site. Where do I need to look to solve this problem?

[Drew_C]

Hi Terren, Do you have anything from GTAC that you can share with the group?

[Terren_Crider]

Negative. The resolution I'm pursuing is to institute a new VLAN to carry 927s current load. It seems to work. The true scope of the issue would likely involve a re-engineering of sorts.

[Jeremy_Gibbs]

How do you have STP configured on that Avaya device? Is it running STP or is it broadcasting out BPDUs of its own with itself labeled as the root bridge?

I am suspecting it is some weird STP config on a device.

[Jeremy_Gibbs]

Weird.. do share the results!