I've got a C3560 with Enhanced (IPSERVICES) image, routing multicast between its VLANs with no external multicast router. It's serving a test environment where developers may generate multicast traffic on arbitrary addresses. Everything is working fine except when someone sends out multicast traffic with TTL=1, in which case the multicast packet suppression fails and the traffic is broadcast to all members of the VLAN.
It looks to me like because the TTL is 1, the multicast routing subsystem doesn't see the packets, so it doesn't create a mroute table entry. If I send out packets with TTL=2 briefly, then switch to TTL=1 packets, they are filtered correctly until the mroute entry expires.
My question: is there some trick to getting the switch to filter the TTL=1 packets, or am I out of luck?
Below are the relevant parts of the config, with a representative VLAN interface. I can provide more info as needed.
#show run ... ip routing ip multicast-routing distributed no ip igmp snooping report-suppression ! interface Vlan44 ip address 172.23.44.1 255.255.255.0 no ip proxy-arp ip pim passive ... #show ip igmp snooping vlan 44 Global IGMP Snooping configuration: ------------------------------------------- IGMP snooping : Enabled IGMPv3 snooping (minimal) : Enabled Report suppression : Disabled TCN solicit query : Disabled TCN flood query count : 2 Robustness variable : 2 Last member query count : 2 Last member query interval : 1000 Vlan 44: -------- IGMP snooping : Enabled IGMPv2 immediate leave : Disabled Multicast router learning mode : pim-dvmrp CGMP interoperability mode : IGMP_ONLY Robustness variable : 2 Last member query count : 2 Last member query interval : 1000