VOIP QOS problems

Discussion in 'Cisco' started by Can2002, Jan 29, 2007.

  1. Can2002

    Can2002 Guest

    I've been trying to configure some QOS functions on my 877W. I've
    followed a number of examples and used the following (trimmed)
    configuration:

    class-map match-any VOIP-Data
    match dscp ef
    class-map match-any VOIP-Signalling
    match dscp cs3

    policy-map QOS-VOIP
    class VOIP-Signalling
    bandwidth 8
    class VOIP-Data
    bandwidth 96
    class class-default
    fair-queue

    Interface Dialer0
    service-policy output QOS-VOIP

    When I do 'show policy-map inter dial 0', I see the following:

    Dialer0

    Service-policy output: QOS-VOIP

    Class-map: VOIP-Signalling (match-any)
    0 packets, 0 bytes
    5 minute offered rate 0 bps, drop rate 0 bps
    Match: dscp cs3 (24)
    0 packets, 0 bytes
    5 minute rate 0 bps
    Queueing
    Output Queue: Conversation 73
    Bandwidth 8 (kbps)Max Threshold 64 (packets)
    (pkts matched/bytes matched) 0/0
    (depth/total drops/no-buffer drops) 0/0/0

    Class-map: VOIP-Data (match-any)
    0 packets, 0 bytes
    5 minute offered rate 0 bps, drop rate 0 bps
    Match: dscp ef (46)
    0 packets, 0 bytes
    5 minute rate 0 bps
    Queueing
    Output Queue: Conversation 74
    Bandwidth 96 (kbps)Max Threshold 64 (packets)
    (pkts matched/bytes matched) 0/0
    (depth/total drops/no-buffer drops) 0/0/0

    Class-map: class-default (match-any)
    0 packets, 0 bytes
    5 minute offered rate 0 bps, drop rate 0 bps
    Match: any
    Queueing
    Flow Based Fair Queueing
    Maximum Number of Hashed Queues 64
    (total queued/total drops/no-buffer drops) 0/0/0

    It's clearly not matching packets, VoIP or otherwise. It's probably a
    really stupid mistake, but I'd appreciate any ideas!

    Cheers,
    Chris

    p.s. I've doe a sniff on the VoIP PBX and can see it sending packets
    with the DSCP field set to EF (0xB8)
     
    Can2002, Jan 29, 2007
    #1
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  2. www.BradReese.Com, Jan 29, 2007
    #2
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  3. Can2002

    Can2002 Guest

    On 29 Jan, 05:01, "www.BradReese.Com" <> wrote:
    > Hi Chris,
    >
    > You may wish to investigate the Cisco Router Configure QoS Template:


    Hi Brad,

    Thanks for that.

    I got to the bottom of the problem after a bit more checking; I'd left
    a route-map entry on my internal interface that was stopping the
    service-policy on the dialer interface. Once I removed it I
    immediatly started getting matches. I can now properly experiment
    with QOS, so I'll definitely take a look at the template!

    Cheers,
    Chris
     
    Can2002, Jan 29, 2007
    #3
  4. Can2002

    Can2002 Guest

    OK, the policy-map is now picking up the traffic, but it's not doing
    much good if I kick off a large upstream file transfer.

    I'm using an ADSL 2048/256 service and I suspect I'm experiencing
    serialization delay. I'm wondering whether it's possible to use the
    policy map to drop packets over a certain size when a VoIP call is in
    progress. I can match packet size in a class-map, I'm just not sure
    how to link that into the policy-map (e.g. I don't want to block every
    large packet, just when a VoIP call is happening).

    Cheers,
    Chris
     
    Can2002, Jan 29, 2007
    #4
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