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Discussion in 'Cisco' started by Ryan, Nov 9, 2007.

  1. Ryan

    Ryan Guest

    I'm pretty new to the world of BGP. I have two main routers as a
    small ISP, each with a connection to an upstream carrier. I'm using
    address space provided by one of those carriers and the two main
    routers are on different subnets. All appears well with the eBGP
    configuration with each router to the upstream carrier. An iBGP
    session is established between my two routers, but I'm confused about
    the iBGP.

    Say I have a client at 2.2.2.2 and I've assigned him address space
    such as 2.2.2.10/29. Previously I would add a route the main router
    which serves as that client's gateway such as:

    ip route 2.2.2.10 255.255.255.248 2.2.2.2

    On my other main router, so that the client subnet was reachable from
    there too, I would add:

    ip route 2.2.2.10 255.255.255.248 <ip of the first main router I
    mentioned>

    This has always worked and continues to work. My question is, now
    that the iBGP session is established, shouldn't a static route on one
    router automatically propagate over to the other router so that I
    don't have to add a static route to the second router? I have no
    prefix-lists in place over the iBGP session. I guess I was expecting
    that all of one routers static routes would propagate over to the
    other router. If that's not the case, how do I control that?
    Ryan, Nov 9, 2007
    #1
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  2. In article <>,
    Ryan <> wrote:

    > I'm pretty new to the world of BGP. I have two main routers as a
    > small ISP, each with a connection to an upstream carrier. I'm using
    > address space provided by one of those carriers and the two main
    > routers are on different subnets. All appears well with the eBGP
    > configuration with each router to the upstream carrier. An iBGP
    > session is established between my two routers, but I'm confused about
    > the iBGP.
    >
    > Say I have a client at 2.2.2.2 and I've assigned him address space
    > such as 2.2.2.10/29. Previously I would add a route the main router
    > which serves as that client's gateway such as:
    >
    > ip route 2.2.2.10 255.255.255.248 2.2.2.2
    >
    > On my other main router, so that the client subnet was reachable from
    > there too, I would add:
    >
    > ip route 2.2.2.10 255.255.255.248 <ip of the first main router I
    > mentioned>
    >
    > This has always worked and continues to work. My question is, now
    > that the iBGP session is established, shouldn't a static route on one
    > router automatically propagate over to the other router so that I
    > don't have to add a static route to the second router? I have no
    > prefix-lists in place over the iBGP session. I guess I was expecting
    > that all of one routers static routes would propagate over to the
    > other router. If that's not the case, how do I control that?


    You need a "redistribute static" statement in your BGP configuration to
    tell it to propagate all the static routes through BGP.

    --
    Barry Margolin,
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***
    Barry Margolin, Nov 9, 2007
    #2
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