simple qos config on cisco router for voice traffic

Unanswered Question
Mar 18th, 2009

Hi all, can anyone give me a simple config for qos for my voice traffic, I need to prioritize the signalling for af21 and payload for ef46

please help



I have this problem too.
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Joseph W. Doherty Wed, 03/18/2009 - 12:54

(For many routers.)

class-map match-any payload

match dscp ef46

class-map match-any signalling

match dscp af21

policy-map simple

class payload

priority . . .

class signalling

bandwidth . . .

interface ?

service-policy output simple

carl_townshend Wed, 03/18/2009 - 14:35

can you tell me what config you would out in these ?

class payload

priority . . .

class signalling

bandwidth . . .


Joseph W. Doherty Wed, 03/18/2009 - 16:44

Unsure what you're asking. If you're wondering about the " . . . ", that's where you specify the bandwidth allocations. Syntax depends on IOS version and how you desire to specify bandwidth; value depends on what your VoIP traffic needs.

carl_townshend Thu, 03/19/2009 - 03:46


thanks for the reply

so, would this be the minimum bandwidth allowed ,what would you normally put for this?

carl_townshend Thu, 03/19/2009 - 04:19


voip codec, g729

max calls say 20

concurrent 10

call signalling h323

dont know about voip keepalives

Joseph W. Doherty Thu, 03/19/2009 - 06:04

According to the following,, G729 uses 24 Kbps per call.

Somewhere on Cisco's site, I recall there's better documentation for bandwidth requirements, but unable to find it at the moment. Hopefully such documentation would also provide bandwidth needed for signalling, although generall that's not too much (10% to 20% of the bearer bandwidth?)

Joseph W. Doherty Thu, 03/19/2009 - 06:50

For the voice bearer traffic, both. (The sample config I provide uses CBWFQ and places the voice bearer traffic into LLQ, which sends its traffic first, but also polices the maximum bandwidth when there's congestion.)

For the signally traffic, bandwidth reservation. (Normal CBWFQ classes, should guarantee a minimum defined bandwith when there's congestion, although more might be used.)


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