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Forum Replies

  1. Hi Jan,

    Before I try to answer your question, I guess you want to be dual-homed so that you have a backup path but you want to be sure that your DC is never used as a transit AS?

    There’s a simple solution for this, you just need to make sure you don’t advertise anything that you receive from ISP1 to ISP2 and the other way around. If that’s what you are looking for then take a look here:

    https://networklessons.com/bgp/bgp-prevent-transit-as/

    If that’s not what you want…let me know and I’ll do my best to answer your question.

    Rene

  2. Hi Daniel,

    I might write a short tutorial on it with an example but it is a simple one. A BGP router will prefer routes that it installed into BGP itself over a route that another router installed in BGP.

    Rene

  3. Before applying AS Path prepending to one side the tie breaker was the router ID?

    if both routers Jim and John have the Same Loopback0 then isn’t the router ID the same also.

  4. Thanks a lot for the explanation Rene.

    I would like you to clarify one more thing.

    For the LAN segment: 192.168.100.0 : R1 is the active router to reach 8.8.8.8 and R2 is the standby as the priority for R1 is 150.

    I am not using interface for tracking as i want the failover to happen on the basis of reachability of 8.8.8.8.

    I have set a tracking object with IP SLA1 for type: echo to ping 8.8.8.8 and mapped it with Standby 1 on R1 to decrement priority by 90 if the ping fails.

    To verify this, I did a “Shut” on the interface of R1 connecting to R3, what happened

    ... Continue reading in our forum

  5. Hello Chris

    BGP will choose the router ID based first on if the router-id command is present. It is not in this case. Secondly, it will choose the highest IPv4 IP address of a loopback interface. You are correct, that both R1 and R3 have the same loopback address (seen in the configs), and thus would be advertising the same router-id. So the next step would be to determine the lowest neighbour IP address, which is indeed 192.168.12.1. So you are correct, it does prefer 192.168.12.1 but not because of the router ID but because of the lowest neighbour IP add

    ... Continue reading in our forum

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