VLAN pruned and then not pruned on SW4, vtp transparent mode
I'm trying to figure out what I just encountered. I'm running through WB1 MPLS, and at the very first task I hit a snag - for some reason I can't ping across vrf VPN_B. I spent quite a while TSing my configs and vrf since I assumed I had done something stupid there.
After quadruple checking everything, I started looking elsewhere. Looking on switches 1 - 4, I looked at the vlans to make sure I had added VLAN 76 (required for the vrf) and sure enough I had. I then looked at interface trunk, and sure enough, there on sw4 in the "forwarding state and not pruned" list, 76 is missing.
I do a show run to make sure there's nothing sneaky on the interfaces, and there's not - just totally standard config. I then do a show vtp status to verify that info - it's running vtp v1 in transparent state. I then run show int trunk again, just to make sure I wasn't seeing things, and all of a sudden, vlan 76 is there and I can ping across my vrf.
Now, clearly, I should have looked at vlans a lot earlier than I did, but I'm trying to figure out what would have caused pruning on a transparent switch to begin with, and more to the point, what would have caused it to suddenly include the vlan. I'm used to occasionally having to clear stuck routes by clearing them - is there a similar command to "clear ip route *" for vlans that I don't know about?