QOS for VOICE

 I want to confirm my approach for QOS over VOICE.

If i come across a question in CCIE R/S lab exam asking to Gaurantee 40% of
banwidth for VOICE Traffic, i would use the following solution :

First, i will classify RTP VOICE payload packets either by:

match ip rtp 16384 16383 ----> This will match all the EVEN UDP ports in
the range 16384 - 32767 ( It does NOT classify RTCP 1720)

or

match protocol rtp audio ----- > this will serve the same funcionality as
of "match ip rtp 16384 16383"

Then, i will apply policy map to the VOICE class-map by using "bandwidth
percent 40"

lastly, i will appy the Service Policy in the appropriate directon.

Please note that i am not classifying RTCP port 1720(TCP Port) for VOICE as
its a TCP port and it will get Reliable service by Acknowledgment,
Re-transmission in case if there is Drop.

But the Voice Payload traffic is UDP, and there is no benefit of
retransmission for dropped packets. Thats the reason i Classify and
Gaurantee Bandwidth to VOICE Payload Packets.

Please give me feedback if my approach is valid?

Also, suggest if there is any need to classify and gaurantee bandwitch to
RTCP 1720 traffic??

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Received on Thu Jul 23 2009 - 13:23:55 ART