nat and asymmetric routing

Discussion in 'Cisco' started by linguafr, Apr 23, 2007.

  1. linguafr

    linguafr Guest

    Is it possible to nat outbound (using same addresses) out a different
    interface than the incoming interface? The lan default gw is on the
    preferred outbound path so traffic would have to reflect off that int
    and get natted. The ISP for the outbound path is partnered with the
    service provider providing the inbound path so they'll honor the
    "foreign" block.

    thanks
     
    linguafr, Apr 23, 2007
    #1
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  2. I'm not sure if I understand your question correctly, but most likely you
    need a feature named "nat on a stick". It allows you to do NAT translation
    to a packets BEFORE they hit the "outside" interface.

    Briefly, how it works:

    1. You create a loopback interface, configure it with IP address, and define
    as "ip nat outside"
    2. You create PBR (policy based routing), to send a packets to loopback
    interface.
    3. After packet hits a loopback interface, and get NATed, packet gets back
    to a routing engine to be routed normal way.
    4. You create another PBR for returning traffic.

    Good luck,

    Mike
    CCNP, CCDP, CCSP, Cisco Voice, MCSE W2K, MCSE+I, Security+, etc.
    CCIE R&S (in progress), CCIE Voice (in progress)
     
    headsetadapter.com, Apr 24, 2007
    #2
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  3. linguafr

    linguafr Guest

    Thanks mike. That's what TAC suggested as well. Pretty clever.
     
    linguafr, Apr 24, 2007
    #3
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