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Advertise NAT pools to BGP

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  • 1.  Advertise NAT pools to BGP

    Posted 09-01-2010 06:08

    NAT Pools:

    1.1.1.0/24

    2.2.2.0/24

    3.3.3.0/24

     

    SRX has interface in only one of these networks (1.1.1.1) with a BGP peer at 1.1.1.254.

     

    Since 1.1.1.0/24 is active in our routing table, no problem getting that into our BGP advertisement.

     

    What is the most appropriate way to inject the 2.2.2.0/24 and 3.3.3.0/24 NAT pools into BGP?

     

    Static route with discard action? Static route with receive action? Other?


    #static
    #JUNOS
    #advertise
    #NAT
    #SRX
    #BGP
    #pool


  • 2.  RE: Advertise NAT pools to BGP
    Best Answer

    Posted 09-01-2010 08:07

    My standard method is to create a discard static route and use that for the BGP export.

     

    There are other methods. Choose one you like best. I like discard, it's worked well for me.

     

    Like this:

     

    routing-options {
        static {
            route 2.0.0.0/24 discard;

      }

    }

     

    policy-options {
        policy-statement public-to-bgp {
            from {
                protocol static;
                route-filter 2.0.0.0/24 exact;
            }
            then accept;
        }
    }

     

    protocols {
        bgp {
            export public-to-bgp;

      }

    }



  • 3.  RE: Advertise NAT pools to BGP

    Posted 06-29-2015 23:50

    Hey

    Is there a more specific route installed?

    If I look at the flow-chart for sessions:

    https://kb.juniper.net/InfoCenter/index?page=content&id=KB16110&smlogin=true

     

    - then source-NAT comes after route-lookup



  • 4.  RE: Advertise NAT pools to BGP

     
    Posted 05-04-2017 05:33

    Just saw your response (I know it's been a few years), but I've been working through the same solution for a customer that has two upstream routers:

     

    I think the reason that this works is that traffic TO the source-nat prefix would always be part of an existing session (eg: outbound traffic has already been source-NATted, return traffic is coming back to the advertised prefixes), so in the SRX Order of Operations, it would skip straight to the Existing Sessions section and avoid route look-up.



  • 5.  RE: Advertise NAT pools to BGP

    Posted 09-01-2010 11:46
    That works. I guess the NAT process grabs it before it actually discards it. It seemed to work that way but it felt counter-intuitive to tell it to discard traffic destined for a network for which I wanted to receive traffic. Thanks for the reply.