VTP PRUNNING BROUGHT NETWORK DOWN!!!

Guys, bizzare situation for one of my clients.

4 7600 switches, 2 L3 (acting as) and 2 L2 (acting as) all in HSRP mode. Few VLANs on L2 are also L3, and there is a VLAN 500 that is setup between these routers as a default gateway. HERE

L3: R1---R2
    | |
    R3 R4

so R3, and R4 in HSRP theyhave 10 vlans that have not been migrated to L3 yet, so in order to go out to the internet they have to go through R1 or R2,

there is a VLAN 500 on all of the routers, and R3,and R4 have ip route 0.0.0.0 0.0.0.0 10.5.100.1 (HSPR ip address for R1 and R2)

when we enable VTP pruning and L2 R3 is the server, VLAN 500 got pruned and internet went down. R1 and R2 are setup in transparent mode.

Why would that vlan get pruned from the trunk?

any ideas..

Marcin Zgola
Internetwork Lead
CCIE #18676
Netrix, LLC
http://www.netrixllc.com
Ph. 847-964-5300
Fax.: 847-964-5350

Blogs and organic groups at http://www.ccie.net
Received on Sun Oct 24 2010 - 03:42:52 ART