Voip and QoS problems!!!!

Unanswered Question
Aug 28th, 2008


I'm working in deploying QoS in a branch office

but I'm getting poor voice quality on calls.

here is the configuration of the QoS parameters

*****************************************class-map match-all VOZ

match dscp ef

class-map match-all VOZ(SIGNAL)

match dscp af31

class-map match-all APLICACION-CRITICA

match access-group name AS400



policy-map POLITICAS-QoS

class VOZ

priority percent 60


bandwidth percent 5


bandwidth percent 10

class class-default






interface FastEthernet0/0

description LAN

ip address

speed auto


interface Serial0/0

description Link to HQ

bandwidth 128

ip address

service-policy output POLITICAS-QoS

load-interval 60

compress stac


interface BRI1/0

no ip address



ip classless

ip route Serial0/0

ip route Serial0/0

no ip http server


ip access-list extended AS400

permit ip any host

Now take a look at the Output of the show policy-map interface serial 0/0

CS-1760-PN#show policy-map interface serial 0/0


Service-policy output: POLITICAS-QoS

Class-map: VOZ (match-all)

1034703 packets, 66220992 bytes

1 minute offered rate 147000 bps, drop rate 71000 bps

Match: dscp ef


Strict Priority

Output Queue: Conversation 40

Bandwidth 60 (%)

Bandwidth 76 (kbps) Burst 1900 (Bytes)

(pkts matched/bytes matched) 1034703/66220992

(total drops/bytes drops) 530418/33946752

Class-map: VOZ(SIGNAL) (match-all)

0 packets, 0 bytes

1 minute offered rate 0 bps, drop rate 0 bps

Match: dscp af31


Output Queue: Conversation 41

Bandwidth 5 (%)

Bandwidth 6 (kbps) Max Threshold 64 (packets)

(pkts matched/bytes matched) 0/0

(depth/total drops/no-buffer drops) 0/0/0

Class-map: APLICACION-CRITICA (match-all)

1423 packets, 84273 bytes

1 minute offered rate 0 bps, drop rate 0 bps

Match: access-group name AS400


Output Queue: Conversation 42

Bandwidth 10 (%)

Bandwidth 12 (kbps) Max Threshold 64 (packets)

(pkts matched/bytes matched) 1423/84273

(depth/total drops/no-buffer drops) 0/0/0

Class-map: class-default (match-any)

38296 packets, 21064743 bytes

1 minute offered rate 47000 bps, drop rate 0 bps

Match: any


Flow Based Fair Queueing

Maximum Number of Hashed Queues 32

(total queued/total drops/no-buffer drops) 11/130/0


As you can see there are A LOT of packets being dropped

related to DSCP ef (voice bearer packets) but there are

actually 0 (ZERO!!) calls being place at this time

Notice that there is also 0 packets matching DSCP af31 (voice signaling)

Can anyone tell me what might be happeing here ??

Why am I getting so many drops ?


I have this problem too.
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