Problems with RTP Header Compression

Sep 15, 2005 4 Replies
B

Has anyone had problems with RTP Header Compression. A customer is running Voice over IP over our MPLS VPN. They are experiencing packet loss and the interfaces are incrementing flushes and output drops. I have run SAA and seen some SAA packets dropped also. The circuits tested clean so I am beginning to suspected RTP Header Compression. It is enabled on all interfaces and it causes the router to process switch so I am thinking this is creating delays and leads to the flushes and the drops.



Am I on the right path? Has anyone else seen a problem with RTP Header Compression?



Bruce snipped-for-privacy@atx.com



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M

process switching would be VERY bad

what IOS version is being used ?

is CEF enabled ?

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B

Yes, CEF is enabled. However, when RTP Header compression is enabled on the interface, packets are process switched. That is why I think RTP Header Compression is causing the voice quality problems we are having.

What do you think?

Merv wrote:

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M

it is a distinct possiblility

check out bug CSCee88022

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W

I'm not too familiar with the topic, but if applying RTP header compression causes process switching to the point of packet loss, maybe it should be removed...seems like the cost far outways the benifits. I guess the real question is how to track it down. How often does it occur? Can they quickly let you know if it's resolved? How many core hops apart are their VPN sites? If they are not too many apart and can schedule some time for testing, remove RTP header compression on the hops that they normally traverse and during a maintenance window and let them test during that time frame.

Regards, Steve

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