[c-nsp] Strange 7200 Ethernet issue over Metro E

[Scott Granados]

So I'm not sure where to start with this one, any pointers would be appreciated.  I'd be happy to google but I'm not sure what the condition is here at all, I'm pretty baffled.

Here's the setup.

A Single 7200 with an NPE400 and a few fast E interfaces.  I have two metro Ethernet pretty standard connections terminated on fast 1/0 and fast 3/0.  Each has trunking enabled and different VLAN tags on each although they share destinations in common.  Our colocation on VLAN 600 on fast 1/0 for example would be 800 on fast 3/0.  There's no overlap in VLAN tags.  On each is attached a /30.  So the config looks something like this.

int fast 1/0
no ip address
no ip proxy arp
no ip directed broadcast
speed 100
duplex full

int fast 1/0.600
encapsulation dot1q 600
ip address 192.168.1.1/30
desc colo

(and so on)
both the same on each interface with the same type of setup just with different tags.

Ok, the problem.

If I bring up link 2 on fast 3/0 all the traffic moves in the outbound direction from fast 1/0 to 3/0 until 1/0 finally settles at 0 bits per second.  No matter whether I play with the routing weights or preferences the traffic still prefers the second interface.  To be honest, I don't even know how traffic on 1/0 would even arrive on 3/0.  This happens even if I shut down the individual sub interfaces, leave only the interface itself up and disable all the routing protocols by hand bound to each neighbor address.  What gives?  Obviously something on layer 2 is going squarely  but with the sub interfaces disabled I don't understand how my traffic redirecting and stranger still arriving at the far end.  What am I missing, I'm quite confused!  I'm guessing something on the carrier providing the Metro E but I'm not sure where to start diagnosing this issue.  Any ideas would be appreciated.

Thanks
Scott