Clock Source Questions for T1 WAN Links

Discussion in 'Cisco' started by news.east.cox.net, Aug 29, 2006.

  1. Hello. We have a Cisco 3640 router at one of our hub sites. It has four
    network modules with two 2MFT-T1 WIC modules each (16 ports total). We
    continuously have timing-related problems (slips, Line Code Violations, Path
    Code Violations) with some of the T1 circuits that are attached. We have
    confirmed that our telco provider does not provide any clocking on our T1
    circuits so we typically pull clock source from one side or ther other, then
    pull it from the line on the other side.

    It seems that the options available "clock source line", "clock source line
    primary" and "clock source internal" all depend on which port the T1 is
    connected to, or what other T1s are connected in the same WICs, or in the
    same network modules.

    Has anyone ever understood the clock source options and how they relate to
    WICs, Network Modules, etc.? If so, I would love to know if there is any
    type of definitive guide available.

    Thank you in advance.

    Tony
     
    news.east.cox.net, Aug 29, 2006
    #1
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  2. news.east.cox.net

    Thrill5 Guest

    "news.east.cox.net" <> wrote in message
    news:5HYIg.6292$SZ3.1963@dukeread04...
    > Hello. We have a Cisco 3640 router at one of our hub sites. It has four
    > network modules with two 2MFT-T1 WIC modules each (16 ports total). We
    > continuously have timing-related problems (slips, Line Code Violations,
    > Path Code Violations) with some of the T1 circuits that are attached. We
    > have confirmed that our telco provider does not provide any clocking on
    > our T1 circuits so we typically pull clock source from one side or ther
    > other, then pull it from the line on the other side.
    >
    > It seems that the options available "clock source line", "clock source
    > line primary" and "clock source internal" all depend on which port the T1
    > is connected to, or what other T1s are connected in the same WICs, or in
    > the same network modules.
    >
    > Has anyone ever understood the clock source options and how they relate to
    > WICs, Network Modules, etc.? If so, I would love to know if there is any
    > type of definitive guide available.
    >
    > Thank you in advance.
    >
    > Tony
    >


    All voice circuits (i.e. a T1) need a clock, but clock is a misnomer for
    what is really needed, which is a stable oscillator, or a common source for
    recovering the "clock" of the circuit. Circuits from the SAME carrier can
    generally share a clock because the carrier will generally have a single
    "clock source" for all their circuits. If you have 3 T1 from the same
    carrier, on one of the T1's you would configure "clock source primary" and
    the rest could be "clock source internal", because the internal clock would
    be synced to the "primary" line. You can also configure each interface as
    "clock source line" which is the default. All T1's need a clock source,
    either your end or their end, and if this is a carrier circuit, than they
    provide the clock and you need either "clock source line" or "clock source
    primary" on one T1, and "clock source internal" on the others. The only
    time you would provide clock by NOT configuring "clock source line" or
    "clock source primary" is if you were connecting a to a PBX and it was
    configure to recover clock for that circuit on that T1, or you were running
    a T1 over your own copper to another device. Since you have the errors
    described above, you do a clocking issue, and they should be configured as
    "clock source line".

    Scott
     
    Thrill5, Aug 30, 2006
    #2
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  3. news.east.cox.net

    Guest

    Thrill5 wrote:
    > "news.east.cox.net" <> wrote in message
    > news:5HYIg.6292$SZ3.1963@dukeread04...
    > > Hello. We have a Cisco 3640 router at one of our hub sites. It has four
    > > network modules with two 2MFT-T1 WIC modules each (16 ports total). We
    > > continuously have timing-related problems (slips, Line Code Violations,
    > > Path Code Violations) with some of the T1 circuits that are attached. We
    > > have confirmed that our telco provider does not provide any clocking on
    > > our T1 circuits so we typically pull clock source from one side or ther
    > > other, then pull it from the line on the other side.
    > >
    > > It seems that the options available "clock source line", "clock source
    > > line primary" and "clock source internal" all depend on which port the T1
    > > is connected to, or what other T1s are connected in the same WICs, or in
    > > the same network modules.
    > >
    > > Has anyone ever understood the clock source options and how they relate to
    > > WICs, Network Modules, etc.? If so, I would love to know if there is any
    > > type of definitive guide available.
    > >
    > > Thank you in advance.
    > >
    > > Tony
    > >

    >
    > All voice circuits (i.e. a T1) need a clock, but clock is a misnomer for
    > what is really needed, which is a stable oscillator, or a common source for
    > recovering the "clock" of the circuit. Circuits from the SAME carrier can
    > generally share a clock because the carrier will generally have a single
    > "clock source" for all their circuits. If you have 3 T1 from the same
    > carrier, on one of the T1's you would configure "clock source primary" and
    > the rest could be "clock source internal", because the internal clock would
    > be synced to the "primary" line. You can also configure each interface as
    > "clock source line" which is the default. All T1's need a clock source,
    > either your end or their end, and if this is a carrier circuit, than they
    > provide the clock and you need either "clock source line" or "clock source
    > primary" on one T1, and "clock source internal" on the others. The only
    > time you would provide clock by NOT configuring "clock source line" or
    > "clock source primary" is if you were connecting a to a PBX and it was
    > configure to recover clock for that circuit on that T1, or you were running
    > a T1 over your own copper to another device. Since you have the errors
    > described above, you do a clocking issue, and they should be configured as
    > "clock source line".
    >
    > Scott


    I have never heard of an E1 where the provider did not
    provide the clock, although I am not that widely experienced
    in this area. T1 is very like an E1.

    You do not say what there T1s are exactly but if they are simple
    data circuits then you definately should try clock source line
    everywhere and see what happens.

    Make sure that you do not cut yourself off from the remote site.
    If desperate consider "reload in x".


    circuits

    Definately try
     
    , Aug 30, 2006
    #3
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