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Multicast flood.


Very strange thing happening:

Several servers sourcing groups from to range. This range contains several groups widely spreaded within it.. Distance between source and destination is 1 hop in the middle (6509). Interface according tcpdump are only receiving join for let's say 230.5.x.x group range, but all groups are represented in this segment and it looks like that router simply join them for no reason. IGMP access list which are applied to the interface giving ability to join only 230.5.x.x range. All interfaces are working in sparse-dense mode of PIM and have right neighbors. Access list which is appied to the intefaces of the client networks giving ability only to join and reply to IGMP query, but not source particular group. CGMP is off.

Question: May be it would be wise idea to enable only sparse mode?

Best regards Matvey.


Re: Multicast flood.

Since there has been no response to your post, it appears to be either too complex or too rare an issue for other forum members to assist you. If you don't get a suitable response to your post, you may wish to review our resources at the online Technical Assistance Center ( or speak with a TAC engineer. You can open a TAC case online at

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

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