From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Mon Jan 22 2007 - 16:19:38 ART
It's based on whether route recursion can occur to an interface.
When you learn a BGP route it will say "via w.x.y.z" in the routing
table. The router internally says "show ip route w.x.y.z" to see if
there is a match, and what the outgoing interface is. The route
recursion process happens until the outgoing interface is found. If the
next-hop cannot be recursed bestpath selection cannot continue and the
BGP route cannot be used.
HTH,
Brian McGahan, CCIE #8593 (R&S/SP)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Mohamed T. Kondela
Sent: Monday, January 22, 2007 1:09 PM
To: Cisco certification
Subject: How BGP verify Next-hop
Any idea what method is used by BGP to verify the next-hop reachability
? How does a BGP router know that the next hop is reachable or not?
Icmp?
Show ip route x.x.x.x ?
I am just trying to know what exactly they are doing in the back ground.
Regards
Mohamed T. Kondela
Senior Network Engineer
IT Dept.
Fax: 4473037 x 303
mtaib@sagia.gov.sa
Saudi Arabian General Investment Authority
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