Simple answer is that the group matches up to the link local MAC address block which is always used for 224.0.0.0/24 groups. Unfortunately the 7600/6500 does the filtering at layer two still, newer platforms typically do l3 filtering. Groups x.0.0.0 x.128.0.0 match to the 00-01-5e-00-00-xx range. There is a 32:1 overlap on MAC addresses for the mulicast addresses. These are always flooded. Best practice is to never use these ranges.
Hope this helps. On Sep 3, 2010 7:26 AM, "Artyom Viklenko" <[email protected]> wrote: > Hi, List! > > I need some help solving strange problem with multicast > traffic forwarding. > > At the main POP we have 7600 router which connected with > two TenGig interfaces to the main backbone ring in the > city. Port Gi3/2 connected to 3560G switch acting as a > multicast router for IPTV. Several PIM neigbors connected > to it via vlans passing through 7600 router. Yesterday > one customer bring up his PIM router and join > all multicast groups (total of 90 in range of 239.0.0.1 > through 239.0.0.90). This lead to 400Mbit/s traffic from > 3560G switch through 7600 router in the customer's vlan. > > Backbone ring include other 7600 router and several 3750E > switches. This ring is L2 with MSTP. > > Later I found that main 7600 router sends all this multicast > traffic to all trunk ports containing customer's vlan including > two TenGig backbone ports and two other GigE ports. > > 7600 router runs 12.2(33)SRD4 Adv. IP Services. > > Mod Ports Card Type Model > --- ---- -------------------------------------- ------------------ > 1 48 CEF720 48 port 1000mb SFP WS-X6748-SFP > 2 8 CEF720 8 port 10GE with DFC WS-X6708-10GE > 3 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX > 5 2 Route Switch Processor 720 (Active) RSP720-3CXL-GE > > Also, ip multicast routing switched on and MVPN vrf configured > on it - have plans to dismiss 3560G as multicast router. > > I try to find any glue in Cisco docs and google - no luck. > > Is it expected behavior or a bug, or misconfig of something. > Why router sends multicast traffic to all ports which members > of customer vlan? There is no igmp joins nor PIM traffic through > some of these ports. > > Please, point me in right direction. > Thanks! > > -- > Sincerely yours, > Artyom Viklenko. > ------------------------------------------------------- > [email protected] | http://www.aws-net.org.ua/~artem > [email protected] | ================================ > FreeBSD: The Power to Serve - http://www.freebsd.org > _______________________________________________ > cisco-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ > _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
