Symptom
HSRP/VRRP transit traffic for certain HSRP groups/VRRP sessions is dropped on the ingress interface even though the groups/sessions are in the Active/Master state.
To operate correctly HSRP and VRRP have to allocate a virtual mac address on the linecards for each HSRP group and VRRP session.
On an ASR9K router running IOS-XR 5.1.0 if HSRP or VRRP are configured with more groups or sessions than the underlying linecard can support, then a virtual mac address will not be allocated for the excess HSRP groups/VRRP sessions, but the groups/sessions will move out of the Init state.
If these groups/sessions get into the Active/Master state the router may start to receive transit traffic that has been forwarded to the groups'/sessions' virtual mac address, but this traffic will be dropped due to the lack of an allocated virtual mac address on the linecard.
Workaround
None
Expected Resolution: Bugfix
Reproducibility (%): 100%
