load-balancing t1s

Discussion in 'Cisco' started by Steve Wolfe, Aug 30, 2005.

  1. Steve Wolfe

    Steve Wolfe Guest

    I have two point-to-point t1 lines, with a 1720 and a 2621 on the ends. I
    was under the impression that by simply having routes of equal costs going
    through both t1s, that packets would be spread among them, at least to some
    extent.

    However, in practice it doesn't work that well. Any one host only seems
    to be able to use a max of about 1.5mbits, and even with multiple
    connections from various hosts, I never get to more than about 2.0 or 2.3
    mbits total throughput. Looking around, I see that nearly all references to
    load-balancing t1s as using CIF, and our feature set (or IOS version)
    doesn't appear to support the commands that they utilize.

    So... do I need a certain feature set in order to make this work, or will
    I need to look at upgrading the IOS version, along with accompanying flash
    and memory?

    steve
     
    Steve Wolfe, Aug 30, 2005
    #1
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  2. Steve Wolfe

    Everton Guest

    In order to run per-packet load-sharing,
    1720 will need either to support CEF
    or have fast-switching disabled.

    So, try disabling fast-swiching, like:

    interface Serial0
    no ip route-cache
    ip load-share per-packet

    Regards,
    Everton
     
    Everton, Aug 30, 2005
    #2
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  3. Steve Wolfe

    Wayne Guest

    "Steve Wolfe" <> wrote in message
    news:...
    >
    > I have two point-to-point t1 lines, with a 1720 and a 2621 on the ends.
    > I
    > was under the impression that by simply having routes of equal costs going
    > through both t1s, that packets would be spread among them, at least to
    > some
    > extent.
    >
    > However, in practice it doesn't work that well. Any one host only seems
    > to be able to use a max of about 1.5mbits, and even with multiple
    > connections from various hosts, I never get to more than about 2.0 or 2.3
    > mbits total throughput. Looking around, I see that nearly all references
    > to
    > load-balancing t1s as using CIF, and our feature set (or IOS version)
    > doesn't appear to support the commands that they utilize.
    >
    > So... do I need a certain feature set in order to make this work, or will
    > I need to look at upgrading the IOS version, along with accompanying flash
    > and memory?
    >
    > steve
    >
    >


    I prefer to use Multilink PPP in this scenario.
     
    Wayne, Aug 31, 2005
    #3
  4. Steve Wolfe

    jsalminen Guest

    Agreed. I tried both solutions and had better results with mppp in regards
    to voip jitter and etc.



    "Wayne" <> wrote in message
    news:%b6Re.291824$x96.234639@attbi_s72...
    >
    > "Steve Wolfe" <> wrote in message
    > news:...
    >>
    >> I have two point-to-point t1 lines, with a 1720 and a 2621 on the ends.
    >> I
    >> was under the impression that by simply having routes of equal costs
    >> going
    >> through both t1s, that packets would be spread among them, at least to
    >> some
    >> extent.
    >>
    >> However, in practice it doesn't work that well. Any one host only seems
    >> to be able to use a max of about 1.5mbits, and even with multiple
    >> connections from various hosts, I never get to more than about 2.0 or 2.3
    >> mbits total throughput. Looking around, I see that nearly all references
    >> to
    >> load-balancing t1s as using CIF, and our feature set (or IOS version)
    >> doesn't appear to support the commands that they utilize.
    >>
    >> So... do I need a certain feature set in order to make this work, or
    >> will
    >> I need to look at upgrading the IOS version, along with accompanying
    >> flash
    >> and memory?
    >>
    >> steve
    >>
    >>

    >
    > I prefer to use Multilink PPP in this scenario.
    >
     
    jsalminen, Sep 5, 2005
    #4
  5. Steve Wolfe

    Ken Johnson Guest

    Just a minor note ...

    per-destination is the Cisco recommended method for voice using IP CEF
    load balancing. Per-destination always uses the same path. Per-packet
    could result in out of order packets.

    If you want to check for yourself, look for the Cisco document
    'Troubleshooting Load Balancing Over Parallel Links Using Cisco Express
    Forwarding'
     
    Ken Johnson, Sep 6, 2005
    #5
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