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New Member

Packet Drops from Priority Queue causing Choppy Voice

Hi all,

I am experiencing voice quality issue at one of my remote sites, when I talk to a user at this remote site I notice the call was cuting in and out but the user at the remote does not experience the issue (call quality is fine for user at remote site), so I am pretty confident the packet drops occur at the remote site and I can see packet drops from the priority queue in "show policy-map interface" command outputs. I've checked and double checked my QoS policy and I couldn't see anything wrong with it and I know bandwidth is not a concern, traffic load is pretty light.

anyone has any idea what would cause packet drops from the priority queue ? Could it be code related ?

I have a 3725 router running IOS version 12.3(14)T7 at this remote site with 4 bonded T1s. Below is the show "policy-map interface" outputs. You can see the total drops at the bottom.

sh policy-map interface atm0/ima0.1

ATM0/IMA0.1: VC 10/50 -

Service-policy output: voice_over_wan

Class-map: voice (match-any)

40631229 packets, 2925446180 bytes

5 minute offered rate 247000 bps, drop rate 0 bps

Match: ip dscp ef (46)

40572438 packets, 2921215020 bytes

5 minute rate 247000 bps

Match: protocol rtp audio

58785 packets, 4230440 bytes

5 minute rate 0 bps

Match: ip precedence 5

5 packets, 648 bytes

5 minute rate 0 bps

Match: access-group 100

0 packets, 0 bytes

5 minute rate 0 bps


Strict Priority

Output Queue: Conversation 136

Bandwidth 65 (%)

Bandwidth 3900 (kbps) Burst 97500 (Bytes)

(pkts matched/bytes matched) 384830/27707760

(total drops/bytes drops) 28704/2066688

Thanks in advance !!!


  • IP Telephony

Re: Packet Drops from Priority Queue causing Choppy Voice

Hi Danny,

I see match ip dscp ef ok,

can you clean statistics, and place some calls to see during that time packet drops increase?

can you check we r not re-writing rtp dscp value before?

Let us know

New Member

Re: Packet Drops from Priority Queue causing Choppy Voice

Hi Gonzalo,

The issue seems to only happens when there is a high call volume but I am confident that bandwidth is not a concern. Should I increase the Queue-limit size for the priority queue ?

Thank you !


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