Symptom:
Aug 23 17:06:31.631 SHYMKEN: %MCAST-SP-STDBY-6-GC_LIMIT_EXCEEDED: IGMP snooping was trying to allocate more Layer 2 entries than what allowed (100000)
Aug 23 17:07:24.427 SHYMKEN: %MCAST-SP-STDBY-6-GC_LIMIT_EXCEEDED: IGMP snooping was trying to allocate more Layer 2 entries than what allowed (100000)

After checking the Mcast MAC addresses and GCE on both Active and standby SP I see following:



On Active Sup SP there are about 10000   static Multicast MAC records like:

SHM-AMTS-PE-01#remote command switch sh mac-address-table static | in 0100.5e
No  Yes  No   997    0100.5e15.057f        static          0   0x4C00
No  Yes  No   997    0100.5e03.438b        static          0   0x3DA8


On Standby SP:

About 13000 so almost equal:

SHM-AMTS-PE-01#remote command standby-sp sh mac-address-table static | in 0100.5e
No  Yes  No   997    0100.5e33.0556        static          0   0x58C0
No  Yes  No   997    0100.5e15.057f        static          0   0x4C00



On Active SP there are about 10000 GCE:

SHM-AMTS-PE-01#remote command switch show mmls verbose gc gce


@@@(C:3121,g:0100.5e7f.fffe):10588430 ltl_bpr: 0x281C, ltl_bpt: 0x281D ltl_bp_nfpoe: 0xFFFFFFFF
Flags: Valid, Hw,         v4,    Proto:0,Oif:0x0
Hardware Ports: 1/147 7/1
IGMP Ports: 1/147
IP groups: 239.255.255.254


On standby SP just above 100000

SHM-AMTS-PE-01#remote command standby-sp show mmls verbose gc gce
@@@(C:3121,g:0100.5e7f.fffe):2294BC58 ltl_bpr: 0x281C, ltl_bpt: 0x281D ltl_bp_nfpoe: 0xFFFFFFFF
Flags: Valid, Hw,         v4,    Proto:0,Oif:0x0
Hardware Ports: 1/147 7/1
IGMP Ports: 1/147
IP groups: 239.255.255.254

Conditions:
Standby Supervisors receiving PIM joins