I have to inject traffic in a dot1q-tunnel and this has to happen in a redundant way. The structure of the underlying network is the following:
There are 2 pairs of switches the first one consists of 2 Catalyst 6509-E which both belong to 1 mst region and the second one is made up of 2 Catalyst 4948 which don't run any kind of spanning-tree. The 2 switches of each pair are connected to each other and this link should be the primary one. There are also 4 connections acting as trunks between these two pairs of switches, so that each switch has one direct connection to each one of the 2 switches of the opposite pair.
To inject the traffic into the Q-in-Q tunnel this structure of 4 direct connections between the switches is repeated. But this time the interfaces of the Catalyst 4849 terminate these links configured with "switchport mode dot1q-tunnel". At the other side the interfaces of the 2 Catalyst 6509-E are configured as trunk with allows only the vlans which had to be insert into the dot1q-tunnel.
My problem is that I can't get this running. With just one of the 4 Q-in-Q links active this works. But if I activate just one of the other 3 Q-in-Q connections this stops working properly. I lose the remote connection to the 2 Catalyst 6509-E and it seems there is a loop. But "debug spanning-tree all" won't show any thing at all at the 2 Catalyst 6509-E.
Has someone of you been able to setup a similar scenario? And/Or can give me some kind of hind in the right direction?
thanks in advance