Voice priority

Unanswered Question

Hi ,

i am running voice using 1751 routers with FXS cards in voip mode.I want to voice to prioritise over data, cos i observe voice breaking when using data at the same time.

I am unable to set "ip precedence' in dial-peer is there any alternate method or what could be the reason i am unable to set ip precenence ?

Also i tried ip qos dscp cs5 mdedia and signalling in dial-peer and still observe the same problem ??

Any suggestions ??


Raj

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rlyons Thu, 05/29/2003 - 10:16
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Hello Susan,


Why can’t you set the IP Precedence in the dial peer? Below is part of a configuration that works perfectly well on 2610’s and 3620’s many IOS versions.


dial-peer voice 22 voip

destination-pattern 56...

session target ipv4:10.88.3.26

ip precedence 5


I guarantee you that the voice packets heading to 10.88.3.26 are marked with an IP Precedence of 5.


Were you trying to put the “precedence” command on the voice over POTS dial peer?


Regards,

Bob


thusain Fri, 05/30/2003 - 10:08
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Raj,


The ip precedence 5 command was replaced with the dscp command. I would set the dscp to ef for media.

ALong with ip precedecne i suggest you use LLQ on your router. THat will give the voice priority over the data.


First lets make an access-list to match the rtp packets :


access-list 101 permit udp any any range 16384 32767


Then we need to apply this to a class-map :


class-map voice

match access-group 101


After that, you have to create a policy map that we will later apply to the interface :


policy-map policy1

class voice

priority 150 <----------- This number should be how much bandwidth you want the voice traffic to reserve for itself.

class class-default

fair-queue



Now all we have to do is apply this to our interface. So under the interface going to the remote side, apply this command :


service-policy output policy1


Hope that answers your question.

rlyons Sun, 06/01/2003 - 12:07
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Hello,


The IP precedence command has not been replaced DSCP marking. DSCP is a more sophisticated and newer method of marking packets that is backward compatible with IP precedence. If you need a finer granularity of packet classification DSCP gives that to you. If you do not need that degree granularity, IP precedence still works just fine.


WFQ, I might add, still prioritizes (actually services that stream) based on IP precedence but does not reserve bandwidth. If you mark via DSCP, WFQ will still recognize the IP precedence bits (of the DSCP classification) and prioritize accordingly.


Regards,

Bob



Anonymous (not verified) Mon, 08/04/2003 - 00:22
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Im having the same problem also.. could you pls elaborate further on how to create policy? where to put and everything? thanks a lot.

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