QoS for Voip

[marman]

Hi,

Please see the output below. As you can see the amount of packets is 11840, and these are marked however in the queue the amount of packets matched is just 179. On my other policies these two figures are the same....could this be a cause of dropping voice calls??

Service-policy output: PIPER-POLICY

Class-map: voice-traffic (match-all)

11840 packets, 781453 bytes

30 second offered rate 22000 bps, drop rate 0 bp

Match: access-group 102

QoS Set

precedence 5

Packets marked 11840

Queueing

Strict Priority

Output Queue: Conversation 72

Bandwidth 100 (kbps) Burst 20000 (Bytes)

(pkts matched/bytes matched) 179/39466

(total drops/bytes drops) 0/0

[r.samuelpeter]

If you are using CBWFQ , QoS will come in to effect in the event of congestion. Although you may mark all the packets but you may not match all the marked packets if there is no congestion in egress interface.

Rob

[marman]

Thanks for the response, we are using LLQ on CBWFQ, please see the class-maps and poliy we have.

class-map match-any decnet

match access-group 111

class-map match-all voice-traffic

match access-group 102

class-map match-all RADAR

match access-group 110

class-map match-all voice-signalling

match access-group 103

class-map match-any VCC

match access-group 112

class-map match-all voice

!

!

policy-map PIPER-POLICY

class voice-traffic

set ip precedence 5

priority 150 20000

class voice-signalling

set ip precedence 5

bandwidth 8

class decnet

police 32000 6000 12000 conform-action transmit exceed-action transmit viol

ate-action drop

class VCC

set ip precedence 4

priority 256 72000

class class-default

fair-queue

!

CAn you see anything that may be causing an issue - thanks

[michael_davis]

marman,

Place your 'marking' policy, where you set ip prec 5, on an ingress interface (service-policy input ...)instead of an egress. And place your queuing policy on egress interfaces (service-policy output ...).

Assuming your access-list 102 is good, you can still match on the same criteria. However, this way, traffic coming into the router is marked, and when it exits, it hits the egress policy and will be priority queued.

However, the best way to do this is match your access-list for the marking policy, and match precedence for queueing.

If I were to guess why you're PQing any ip prec 5 (dscp ef) traffic, I'd guess it is because this router is a Gateway as well. And by default, it will generate rtp traffic with ef/ip-prec 5 set. Such traffic will be priority queued.

Another protocol that Cisco automatically marks prec 5 is DLSW.

Let me know if this helps.

[nchidamb]

" 11840 packets " were classified and put into 'voice-traffic' queue. ' Pkts matched 179 ' means that due to congestion 179 packets were queued. So, the less you see in ' pkts matched ' is better for the voice. Based on your brief desription I would say look for other things if voice calls are dropping.

-Nat