From: Mike Haddad (mike.haddad@hotmail.com)
Date: Mon Mar 10 2008 - 01:57:15 ARST
You're right Sadiq the best way is to lab it myself. I did a lab and it turned
out that the no-prepend means that when I pass the routes to other neighbors
don't prepend this AS to the AS Path list. Therefore, I have done a lab as
follows:
- R5 AS 100 Peering with R2 and R1 who are actually in AS 200 but has the
local-as set to 300
- From R5 perspective whether we have no-prepend or not it will see the routes
as 300 200
However
- R1 and R2 are peering with other neighbors.
Using no-prepend will show the routes as learned from AS 200 on these other
neighbors
Without no-prepend option will show the routes as learned from AS 300 200 on
these other neighbors
Therefore, no-prepend prevents adding the local-as into the As-path and the
target is that to prevent AS300 from dropping the routes if it sees it's own
AS is in the path. This is in case we have some other BGP peering with AS300
somewhere.
Regards,
> Date: Sun, 9 Mar 2008 00:29:57 +0000> From: sadiqtanko@gmail.com> To:
mike.haddad@hotmail.com> Subject: Re: local-as no-prepend Question> CC:
ccielab@groupstudy.com> > Mike,> > The best way to have to concept stick in
for good is to lab it up and> see for yourself really.> > Anyways, I know it
works inbound but have never been curious to check> the remote router for the
outbound prefixes actually. Check it out> here too> >
http://www.cisco.com/en/US/docs/ios/12_4/ip_route/configuration/guide/hbgphla
.html> > HTH> > Sadiq> >
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