Some users experiencing echo/bad quality voice

[Ken Lee]

Hi,

Anyone has comments for the configuration below?

policy-map CBQ_2M
class class_Net_Critical
    bandwidth remaining percent 6
    queue-limit 64 packets
class class1-voice
    priority 570
class class1-video
    bandwidth remaining percent 22
    queue-limit 128 packets
class class2-signalling
    bandwidth remaining percent 6
    queue-limit 64 packets
class class2
    bandwidth remaining percent 31
    queue-limit 75 packets
class class4
    bandwidth remaining percent 6
    queue-limit 64 packets
class class-default
    bandwidth remaining percent 25
    queue-limit 95 packets
policy-map shape_2M
class class-default
    shape average 1900000 19000
  service-policy CBQ_2M
!
!

Sh policy-map as below:

   Class-map: class1-voice (match-any)
          4363727 packets, 369848116 bytes
          30 second offered rate 29000 bps, drop rate 0 bps
          Match:  dscp ef (46)
            4363727 packets, 369848042 bytes
            30 second rate 29000 bps
          Priority: 570 kbps, burst bytes 14250, b/w exceed drops: 3933
       

Users are experiencing echo and bad quality.. I am not sure if it is the configuration on the QoS side or it is a pure bad quality. The thing is there is no over-subscribe bandwitdh as the maximum bandwitdh for the day it reaches is 1.5M out of 2M. The users based are around 55 users.

Any advise will be great!!

Thanks in advance!

KA

[sean_evershed]

It looks like that you are getting dropped packets in your priority queue.

How are you measuring the bandwidth? Is it a 1 minute or 5 minute polling interval?

Do the local phones need to register with a remote PABX / Call Manager server in another office?

Can you post the config of your class maps as well?

On the outbound interface, when you issue the command Show Interface, what figure do you get for Available Bandwidth? Up to 25% of your bandwidth can be reserved by the router for overhead traffic such as routing protocols etc.

[Ken Lee]

  Sean,

As below: Where can i get Available bandwitdh?

30 second input rate 178000 bits/sec, 71 packets/sec
  30 second output rate 72000 bits/sec, 69 packets/sec

Class Map match-any class-video (id 3)
   Match   dscp cs4 (32)
   Match   dscp af41 (34)
   Match   dscp af42 (36)
   Match   dscp af43 (38)

Class Map match-any class-voice (id 2)
   Match   dscp ef (46)

Class Map match-any class-Network-Critical (id 1)
   Match access-group name acl-Routing

Class Map match-any class-default (id 0)
   Match any

Class Map match-any class4 (id 6)
   Match   dscp cs1 (8)
   Match   dscp af11 (10)
   Match   dscp af12 (12)
   Match   dscp af13 (14)

Class Map match-any class02(id 5)
   Match   dscp af31 (26)
   Match   dscp af32 (28)
   Match   dscp af33 (30)

Class Map match-any class02-signal (id 4)
   Match   dscp cs3 (24)

[Edison Ortiz · Accepted solution]

Increase the Priority Queue value, 570kbps doesn't seem to be enough.

Your calculation must be based on the number of phones the location has and the codec that is used.

Your VoIP vendor should have bandwidth requirement for each unit.

[Ken Lee]

Edison ,

Thanks for your advise! there are 55 IP phones at the branch. The codec is G.729.

Are you able to advise what is the best priority queue I can go with?  Appreciate that..

Sean,

Thanks too! I will post the config to you soon by removing the sensitive info on the config. So you and Edison can run through again.

Thanks,

Regards,

KA

[cadet alain · Accepted solution]

Hi,

To calculate bandwidth requirements you can use this tool if you have a valid cco login:

http://tools.cisco.com/Support/VBC/do/CodecCalc1.do

You can also look here: http://www.voip-info.org/wiki/view/Bandwidth+consumption

Regards.

Alain.