General

Multicast Data packet came into the device interface properly but drop with following log 2020 Aug 5 18:12:05.277795 mcastfwd [28387]: [28476]: Discarding the packet with src ip x.x.x.x dst ip 239.x.x.x rcvd on ip_msg_l2_iod c Etherneta/b/c vlan m. Mcastfwd not initialized to OTV or ORIB This log means Multicast packet punt to CPU and Drop. Therefore IP Pim register never sent. S,G is not in the MRIB even though RP has the *,g

Symptom

S,G never built even though the data packet is hitting the L2 interface. IP PIM register is never generated by CPU due to data packet getting dropped inside CPU.

Conditions

N3K-C3172PQ-10GE as transition switch between L3 PIM and L2 Multicast. Data packet hitting L2 interface. L3 connected to the RP with PIM enabled No OTV enabled at all

Workaround

Flapping the corresponding SVI M will fix the issue or use static OIL. Applying static OIL makes it work. Even after static OIL removal, the working state still remains. The issue will trigger once again, after the sender stops sending packets for a while and the S,G timed out.

Further Problem Description