IP planning for 2 connections to the ISP

Discussion in 'Cisco' started by Gary, Oct 17, 2003.

  1. Gary

    Gary Guest

    We are the ISp and the customer currently has one T1 to us using unnumbered
    interfaces. Simple.

    We are installing an additional link using LES(Lan Extension Servces) or
    10MB Ethernet.

    The questions is can I run the Ethernet as unnumbered also ??? or should I
    just give it any old ip address

    If I create static route statements at our end (ISP) saying send some
    traffic down the serial link and some down the ethernet link what should I
    use for the ethernet link in my route statements

    For the serial line we just use the serial name etc, so I guess for the
    ethernet we just use the ethernet

    i.e
    ip route 1.2.3.0 255.255.255.0 serial 0 with one low weight
    ip route 1.2.3.0 255.255.255.0 ethernet 0 with a higher weighting

    and do the same thing in reverse at the customer site.

    i.e
    ip route 0.0.0.0 0.0.0.0 serial 0 with one low weight
    ip route 0.0.0.0 0.0.0.0 ethernet 0 with a higher weighting
     
    Gary, Oct 17, 2003
    #1
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  2. Gary

    ZeroKool Guest

    You should be able to however its advised to use small /30 subnet if
    possible on each end.
    if you are trying to load balance traffic it would work like this. You might
    have to use CEF or someother way to load balance however I am not sure why
    would you load blanace a 10mbps connection with T-1?


    I would sugdest to use IP's rather than interfaces when you are using ip
    route command it will make life easier and also if have to do hardware
    upgrades later you wouldn't have to worry about route comamnds.
     
    ZeroKool, Oct 19, 2003
    #2
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  3. Gary

    shope Guest

    Agreed - trying to load balance 2 dissimilar speed links like this doesnt
    tend to work well, as the load balancing doesnt understand the relative
    speeds of the circuits.

    Either it works out you have 10m and 1.5 M in parallel - so you get 15% more
    throughput in perfect conditions (unbelievably unlikely), or it treats the 2
    links as equivalent, and slows the Ethernet to the speed of the T1.
    1 further issue - i dont think that you can rely on the Ethernet interface
    going down if you loose IP access via the LES circuit - which means that the
    router wont invalidate the static route when the link fails.

    If you want to have resiliencethat reacts to link failure you may need to
    run a routing protocol over the link - with the co-operation of your ISP.
     
    shope, Oct 19, 2003
    #3
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