SSM Multicast Group Verification
When using source specific multicast it is possible to determine if a multicast group is using SSM or not by using the following commands:
R2#show ip mroute 232.1.1.1 IP Multicast Routing Table Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected, L - Local, P - Pruned, R - RP-bit set, F - Register flag, T - SPT-bit set, J - Join SPT, M - MSDP created entry, X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement, U - URD, I - Received Source Specific Host Report, Z - Multicast Tunnel, z - MDT-data group sender, Y - Joined MDT-data group, y - Sending to MDT-data group Outgoing interface flags: H - Hardware switched, A - Assert winner Timers: Uptime/Expires Interface state: Interface, Next-Hop or VCD, State/Mode (192.168.12.1, 232.1.1.1), 00:00:18/00:03:10, flags: sT Incoming interface: FastEthernet0/0, RPF nbr 192.168.12.1 Outgoing interface list: FastEthernet0/1, Forward/Sparse, 00:00:18/00:03:10
Note that the route has flags "sT". The "s" indicates that this belongs to an SSM group.
Similarly, additional information about the SSM status of a group can be found using the following IGMP command:
R3#show ip igmp groups 232.1.1.1 detail Flags: L - Local, U - User, SG - Static Group, VG - Virtual Group, SS - Static Source, VS - Virtual Source, Ac - Group accounted towards access control limit Interface: FastEthernet0/0 Group: 232.1.1.1 Flags: L SSM Uptime: 00:04:30 Group mode: INCLUDE Last reporter: 192.168.23.3 Group source list: (C - Cisco Src Report, U - URD, R - Remote, S - Static, V - Virtual, M - SSM Mapping, L - Local, Ac - Channel accounted towards access control limit) Source Address Uptime v3 Exp CSR Exp Fwd Flags 192.168.12.1 00:04:30 00:02:34 stopped Yes RL
Notice here the "SSM" flag that appears for the group, indicating that it is an SSM multicast group.
Links
https://networklessons.com/multicast/source-specific-multicast-ssm