BGP best path selection process part-2

Networking CCNP Enterprise
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1

Hi @Network_Eric

another lab for testing
another lab for testing985×652 41.1 KB

your last answer was very impressive
sir, what do you think the wrong in this lab ?

i want to test if R5 is going to select the best next hop based on the lowest AD value or based on the lowest RID or based on the lowest metric .

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Hey Major,

So a bit of detail here.

  • The next hop will never be based on Administrative Distance in this lab, as all routes are from eBGP, which is an AD of 20. That means all of the routes have identical ADs. We don’t calculate the AD of the route to the next hop in determining which route to select with BGP. If we have an IGP running, we can use the cost within the IGP to determine the best route in BGP.
  • Lowest metric will not be used because you do no have it forcing a check for MED. MED is only default checked if you have two different paths to the same external AS. So, if all of the neighbors were in one AS, then we could use metric to determine if this is the path to select.
    *Router ID is used to select only after the oldest route has been removed from the routing table.

Since you created another thread for BGP oldest route, I will go into detail on that there.

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