BGP path selection process

Routing & Switching BGP
1

Hi All,

Can anybody help to understand the below Questions?

  1. BGP path selection process in step by step.
  2. Can you explain the below statement with scenario to understand.
    A network in the BGP table with a next hop address of 0.0.0.0 means that the network is locally originated via redistribution of Interior Gateway Protocol (IGP) into BGP, or via a network or aggregate command in the BGP configuration
2

In answer to number 2…

Every route that goes into BGP comes from somewhere else to begin with. When this is from a connected interface, or static route, on a particular router, then when you look at the BGP table (i.e. “show ip bgp x.x.x.x” on a Cisco) for that prefix the “next hop” attribute is set to 0.0.0.0. That’s because the “next hop” is that very router itself. It means the router will not send traffic for that IP to another router based on the BGP route, but that the routing table on that router has a way to get to the destination locally.

Hope that makes sense!

3

As for #1, there is no point in repeating Cisco’s excellent document on the subject:

4

A post was merged into an existing topic: BGP Attributes and Path Selection