Diffserv marked pockets

Discussion in 'Cisco' started by Alex Turtois, Mar 14, 2006.

  1. Alex Turtois

    Alex Turtois Guest

    Dear All,

    I was reading through the groups archive looking for information on
    setting diffserv on cisco routers. I have only one question stayed

    I have a bunch of VoIP boxes eg sipura, grandstream, audiocodes here to
    test with. each of them has different style of setting up diffserv
    values. one needs 43, the other 0xb8, etc etc,

    Are all different boxes marking pockets different ways? What I'm
    missing here?

    The question is how can I set up the cco to match up these values? has
    anyone did it previously?

    Any help is greatly appreciated,
    Alex Turtois, Mar 14, 2006
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  2. Alex Turtois

    Merv Guest

    For VOIP, the correct DiffServ value is EF (Expedited Forwarding).

    The EF DiffServ also contains the ToS Low Delay bit, which is treated
    by many routers without any configuration. This is called PFIFO
    (Priority Fist In First Out, or FIFO with Priority).

    EF DiffServ decimal: 184
    EF DiffServ hexadecimal: 0xb8
    EF DiffServ binary: 10111000

    EF DSCP decimal: 46
    EF DSCP hexadecimal: 0x2e
    EF DSCP binary: 101110

    Remark: The DSCP field is contained within the 6 first bits of the
    DiffServ byte.

    The recommended DSCP value for EF PHB is 101110.

    For more information about EF PHB, refer to RFC 2598, An Expedited
    Forwarding PHB.

    Vendors may be configuring the EF value in different way - i.e. in hex
    which would be 0xb8.

    The bottom line is when the VOIP packet are put on the wire the Differv
    value should be EF.

    When acquiring VOIP phones, ensure they are RFC 2598 compliant.
    Merv, Mar 14, 2006
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  3. Alex Turtois

    Alex Turtois Guest

    Thanks a LOT, that made my mind clear.
    Alex Turtois, Mar 14, 2006
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