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New Member

Multicast routing

Hello.

I try to configure multicast routing based on PIM Dense mode on two catalyst 3750 (C3750-ADVIPSERVICESK). Catalysts connects to each other through L3 interfaces.

all catalyst are multicast enabled routers. When I ping multicast group from source computer, i recieve icmp reply from all multicast subscribers in all network segments. (i view this through sniffer). But then i try send Video to multicast group (UDP Packets), packets recieves only subscribers in same network segment as source.

sh ip mroute <Group ip> shows correct information on both catalysts (i think :-) )

sh ip pim ne shows correct neighbour

mtrace passed OK.

I have't any ACL for inbound IGMP access group and for interfaces.

i don't understand this behavior.:-(

any suggestion ? Thanks

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Multicast routing

hi dimitavton,

with your posting i had come to know that ppl. in the same network can able to receive the video stream & rest of the network cannot receive the video stream, though they are in the same multicast group isn't? if that is the case, you need increase your TTL value in the video streaming server, by default the value is "O"

you would need to increase based on how many routers it has to stream.

hope this helps.

rate this post.

5 REPLIES

Re: Multicast routing

hi dimitavton,

with your posting i had come to know that ppl. in the same network can able to receive the video stream & rest of the network cannot receive the video stream, though they are in the same multicast group isn't? if that is the case, you need increase your TTL value in the video streaming server, by default the value is "O"

you would need to increase based on how many routers it has to stream.

hope this helps.

rate this post.

New Member

Re: Multicast routing

thanks for quick response.

i thought about ttl.

ttl=200. these is enough to pass two routers

Re: Multicast routing

since it is passing 2 routers, you can set the TTL=2.

forgot to rate the post.

New Member

Re: Multicast routing

You're right!!!! Thanks.

My video server is VLC media player. I set up ttl for my video stream (this is feature of program), but general programs settings TTL (ttl=1) overrided my setting.

Re: Multicast routing

by any chance the group you're using is 224.0.0.x? Routers should not forward packets for this group.

Sniffer might be deceptive since at least with some catalyst software enabling 'ip igmp snooping' has strange side effect - interVLAN hopping for mcast traffic (but not for unicast).

Could you post output of 'sh ip mroute ' command from each switch/router?

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