Two ISPs, One 3640 Router, and PIX 515 with one outside interface

Discussion in 'Cisco' started by TechGuy, Aug 2, 2004.

  1. TechGuy

    TechGuy Guest

    Where do I begin explaining the problem and what we are trying to do.

    We have a internet T1 coming into a Cisco 3640 which then heads over
    to our PIX before hitting out LAN.

    The outside interface on the PIX uses one of our external IP's given
    by our ISP.

    Now we have a second internet connection terminating in our 3640, with
    a different ISP and different set of external IPs obviously. Our
    problem is with getting traffic to and from the PIX due to the single
    outside interface on the PIX having an external IP of our original

    We have tried doing nat on the PIX and the router but it is becoming
    to problematic and difficult.

    One idea was to put another interface in on the PIX and make it an
    outside interface as well having it connected to the 3640.

    We are not looking to send our default route (internet traffic) out of
    the new interface. Instead we just want to use it for static
    mappings. Just not sure if you can even have multiple outside
    interfaces on the PIX.

    Any ideas and thoughts on this would be appreciated.
    TechGuy, Aug 2, 2004
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  2. Run BGP w/ both ISP's and save yourself the anguish of coming up with
    complex configs which will be less than reliable.
    Joseph Finley, Aug 2, 2004
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  3. TechGuy

    PES Guest

    I would do nat in the Pix. Make sure that the router has a route to the
    external interface of the Pix for all ip addresses that are not included in
    the subnet of its ethernet interface. Set the default route to the default
    ISP. Create the static mappings as desired. Use policy routing on the 3640
    to send the packets sourced from the ip's that are statically nat'd to the
    proper isp. I would go ahead and create the policy to send anything sourced
    from the entire address pool assigned by the isp for the static nats to use
    the policy.
    PES, Aug 3, 2004
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