[36176] in North American Network Operators' Group
FW: Next Hop Attribute
daemon@ATHENA.MIT.EDU (Charles Smith)
Thu Mar 29 09:38:18 2001
From: "Charles Smith" <chasmith9@hotmail.com>
To: nanog@merit.edu
Date: Thu, 29 Mar 2001 14:28:55 -0000
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re-posted for broader audience:
My apologies if this has been discussed recently...
Is there a collective wisdom as to why the BGP RFC makes the statements that
it does about the BGP next hop attribute? Specifically:
(From RFC 1771): "A BGP speaker must never advertise an address of a peer to
that peer
as a NEXT_HOP, for a route that the speaker is originating. A BGP
speaker must never install a route with itself as the next hop.
When a BGP speaker advertises the route to a BGP speaker located in
its own autonomous system, the advertising speaker shall not modify
the NEXT_HOP attribute associated with the route. When a BGP speaker
receives the route via an internal link, it may forward packets to
the NEXT_HOP address if the address contained in the attribute is on
a common subnet with the local and remote BGP speakers."
At routers that have EBGP session injecting routes into its own AS on Cisco
routers we set the next-hop-self attribute to eliminate synchronization
issues, but I'm curious as to why the RFC made these requirements in the
first place?
Thank you for any brain cycles spent on this.
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