Jitter

Unanswered Question
Jun 28th, 2007

We have LLQ on all our WAN links (E3) to prioritize the voice traffic, but we still seeing high Jitter, it can reach as high as 98ms. The voice quality is very poor (breakups). How should we solve that?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
Paolo Bevilacqua Thu, 06/28/2007 - 05:13

You can use QoS / LLQ on the points of congestion, but what are the voice endpoints that you are using, and what codec? 98ms should be easily dealt with, by cisco phones and routers with recent IOS and DSP firmware.

Ahmede Thu, 06/28/2007 - 05:23

We are using G729 and we are already have QoS/LLQ end to end, but we are still seeing the problem..

Paolo Bevilacqua Thu, 06/28/2007 - 05:27

Hi,

the thing is that g.729 is very sensitive to both jitter and packet loss. In that sense, G.711 would give you much better results.

In any case, if you observe jitter and/or packet loss, it means that QoS/LLQ in some point is not working, so should you should go step by step to find where and why.

vdilys Thu, 07/05/2007 - 21:25

Have you try to post "sh run"?

Looks like policy-map configuration issue.

Are fool E3 is used for IP traffic?

Stoyan Stoitsev Thu, 07/05/2007 - 22:40

What WAN are you using?

On your router issue

sh policy-map interface fastEthernet 0/1

with the interface that has the

service-policy output

You should get a similar output:

sh policy-map interface fastEthernet 0/1

FastEthernet0/1

Service-policy output: NET

Class-map: WEB (match-any)

7759 packets, 5701469 bytes

1 minute offered rate 406000 bps, drop rate 0 bps

Match: protocol http

6527 packets, 4962271 bytes

1 minute rate 359000 bps

Match: protocol secure-http

1153 packets, 703001 bytes

1 minute rate 47000 bps

and so on.

Basically you should see some packets being matched. If you don't, then you have a configuration problem.

If you are using some access lists to define interesting traffic try

sh ip access-list Emule

Extended IP access list Emule

10 permit tcp any eq 4662 any (161451 matches)

20 permit tcp any any eq 4662 (169896 matches)

Again you should see matching packets.

Would be easier if we could see your QoS config.

BR

Stoyan

Prakash Chauhan Thu, 07/05/2007 - 23:16

Hi,

I believe 98 ms jitter will be controllable as thumbrule for voice is 150ms round trip will be acceptable...

well did u check voice quiatly... is it poor??? and also confirm whether packet drop is there or not in whole network.... well as suggested if your configuration is alright then there must not any packet loss or jitter... also u need to chek physical connecitity with network and might other interfaces also do congestion if switch is used in network for connecitivity...

well waiting for configuration from end to end as well as n/w diagram if possible...

BR

Prakash Chauhan

Actions

This Discussion