IMA Group Cisco 3660

[jps3700]

I am in the process of migrating a 6MB (4 T1) IMA Circuit from a 3640 to 3660 to facilitate an upcoming bandwdith increase on this group and have run into a problem.

On the 3640, if I unplug one of T1's assigned to the IMA group, the group remains up (as it should). However when I perform the same test on the 3660, the entire IMA Group goes down.

The configuration is idential between the 3640 and 3660, the only difference is the IMA card, its a 4-port on the 3640 and an 8-port on 3660.

When issuing a show ima interface command it shows insufficent links, so I set minium links to 2 and still the same issue occurs.

Configuration is as follows:

interface ATM1/0
no ip address
no atm oversubscribe
no atm ilmi-keepalive
ima-group 0
no scrambling-payload
!
interface ATM1/1
no ip address
no atm oversubscribe
no atm ilmi-keepalive
ima-group 0
no scrambling-payload
!
interface ATM1/2
no ip address
no atm oversubscribe
no atm ilmi-keepalive
ima-group 0
no scrambling-payload
!
interface ATM1/3
no ip address
no atm oversubscribe
no atm ilmi-keepalive
ima-group 0
no scrambling-payload

interface ATM1/IMA0
no ip address
ip route-cache flow
no atm ilmi-keepalive
ima active-links-minimum 2
!
interface ATM1/IMA0.777 point-to-point
ip address x.x.x.x 255.255.255.252
pvc ATT-IMA 1/777
vbr-nrt 6000 6000
oam-pvc manage 0
encapsulation aal5snap

Any assistance would be greatly appreciated.