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New Member

Get BGP to use least AS hops with 2 routers

I have a common setup with 2 BGP routers going to 2 different ISPs and taking in full BGP routes. Is there an easy way to get router 1 to use the least AS hops if it is through router 2? The eBGP routes have a lower admin value and will always be preffered over iBGP routes even if they are more AS hops. I would prefer not to run OSPF or get a 3rd router. Can the admin value of iBGP just be decreased to 20 to solve this?

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Bronze

Re: Get BGP to use least AS hops with 2 routers

Administrative distance are used when comparing between 2 different routing protocols. For instance, eBGP vs OSPF.

Within BGP (eBGP vs iBGP), the BGP Path Algorithm is used instead.

HTH,

__

Edison.

3 REPLIES
Hall of Fame Super Bronze

Re: Get BGP to use least AS hops with 2 routers

Please take a moment and read the "BGP Best Path Selection" at:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml

"Prefer the path with the shortest AS_PATH."

goes before

"Prefer eBGP over iBGP paths"

__

Edison.

New Member

Re: Get BGP to use least AS hops with 2 routers

That is the way that I assumed that it worked until I read some Cisco doc that said that eBGP with an admin distance of 20 will always be preferred over the same iBGP route with an admin distance of 200. That made sense to me since admin distances are normally considered before a routing protocols metric.

Hall of Fame Super Bronze

Re: Get BGP to use least AS hops with 2 routers

Administrative distance are used when comparing between 2 different routing protocols. For instance, eBGP vs OSPF.

Within BGP (eBGP vs iBGP), the BGP Path Algorithm is used instead.

HTH,

__

Edison.

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