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multicast packet totaly flood my network...


I have a 7206 vxr router and 4506 switch and cisco call manager in my HO. 25 branch office is connected with HO via 2mbps point to point lease line through EIGRP routing protocol. In branch office 2811 router, 2950 switch and cisco ip phone are there. I have a video conferencing server at HO , its working in multicasting mode. That's why I am defining a RP at central location and enable multicasting at every ports of all routers. Also voice and data are running. All are working fine. But problem is that at time of Video conference, multicast packet totally block the band width, I want to save bandwidth,

I want to create separate VLAN for voice, video and data, enable the qos… .. CGMP or IGMP spoofing…………. basically I am totally confused, please help me…..

Please send me some configuration file if possible


Tirtha Sarathi

Hall of Fame Super Silver

Re: multicast packet totaly flood my network...

Hello Tirtha,

you need to implement at least QoS.

Verify also the configuration of the videoconferencing server because they can default to high bit rate codec.

So setting a default codec that uses less bandwidth is important.

Also you should look for some control mechanisms like CAC = Call admission control so that no more then X distinct multicast sessions can be setup.

configuration of IGMP snooping on switches can be a benefit but it is important to verify that the implementation is efficient and doesn't load too much the switch cpu (some investigation on C2950 capabilities is needed).

Using separate Vlans can help but you should be able to implement modular QoS checking the L4 information in packets.

You should provide a LLQ class for VoIP, a class for video, a class for VoIP signalling, a class for data (at least one). CBWFQ can be the right tool to manage BW resources on 2 Mbps links.

Hope to help


Community Member

Re: multicast packet totaly flood my network...

can u provide any sample configuration?



Hall of Fame Super Silver

Re: multicast packet totaly flood my network...

Hello Tirtha,

sorry for late answer.

C2950 supports igmp snooping and it is enabled by default.

about QoS I would suggest to have a look at this SRND about QOS

there is a chapter about branch routers and the examples include a class for video.

You can start from these examples and customize them to your needs.

Video conferencing server tuning is important too as I explained in my first post.

Hope to help


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