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Forum Replies

  1. Nicholas,
    The reason for this is why BGP is different from other routing protocols. In fact, it is legitimate to view BGP not as a routing protocol at all, but instead as an application that supplies you with what’s called NLRI (Network Layer Reachability Information). Think of it this way: While routing protocols tell you HOW to get somewhere (they are always concerned with the next hop on a hop-by-hop basis), BGP tells you WHERE you need to go, but not how. It is up to the router to figure out how to get to the destination supplied by BGP, by looking at i

    ... Continue reading in our forum

  2. Hi Hoan,

    iBGP uses split horizon which means that it won’t advertise prefixes to iBGP neighbors that is has learned from other iBGP neighbors. You can read more about it here:

    Internal BGP explained


  3. Hello Brian

    It’s nice to see how you are working through the problem and we can “read your thoughts” along the way.

    So, having answered your own original question, here’s the question that I’ll try to answer:

    You must remember one of the fundamental laws of rou

    ... Continue reading in our forum

  4. OMG!

    So I can apply that rule to routes? Meaning as long as it can get there it will be added just not reachable because it knows how to get there but not the way back.

    That does make perfect sense…gosh… I should have thought about that or at least posed it as a question. I was thinking that it probably had to do with some rule I had learned at some point about TCP/IP and traffic movement but just didn’t think of what was right in front of me. I hate when I do that but that happens a lot lol…

    Ok now that makes sense and I can put it in a nice little box and label it lol… thanks!

  5. Yeah, so to summarise:

    Learned from eBGP -> Advertise to eBGP -> Next-hop-self automatic

    Learned from eBGP -> Advertise to iBGP -> “Next-hop-self” required

    Learned from iBGP -> Advertise to iBGP -> “Next-hop-self all” required

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