Symptom
After exhausting the multicast hardware resources (RSC_RIL INDEX by m-cast adjacencies) the standby switch experiences unicast connectivity issues on layer 3 interfaces.
The TCAM doesn’t seem to be exhausted by multicast entries. However, RSC_RIL INDEX is almost completely depleted.
WEB43951-WEB43952#show platfo hardw fed sw sta fwd-asic reso tcam utili
CAM Utilization for ASIC [0]
Table Max Values Used Values
--------------------------------------------------------------------------------
Unicast MAC addresses 65536/1024 4070/21
L3 Multicast entries 16384/1024 1248/9
L2 Multicast entries 16384/1024 176/11
Switch#show platform hardware fed sw sta fwd-asic resource uti | in RSC_RIL_INDEX
Resource Name Allocated Free
------------------------------------------
RSC_RIL_INDEX 32765 3
RSC_RIL INDEX can be seen as the resource that handles the m-cast adjacencies in hardware and it’s directly related to the number of OIFs, SVI interfaces and multicast groups. The higher number of OIFs and m-cast groups, the higher number of RSC_RIL indexes the switch will require to handle the traffic.
The problem takes about 5 days to appear.
Conditions
C9500 in StackWiseVirtual mode.
The problem was reported in IOS-XE release 16.12.2.
Workaround
Track and address the root cause that triggers the multicast hardware exhaustion.
Further Problem Description
This problem has not been seen if the maximum hardware capacity is not exceeded.
