[j-nsp] BGP Origin Issue

Jeff Tantsura jeff.tantsura at sscplus.nl
Fri Apr 20 10:42:23 EDT 2007


Hi,

My bad, described behaviour was true back in 2001.
In nowadays both cisco and juniper set by default origin for aggregated
routes to IGP.

Jeff

P.S. Sorry for all the mails, bloody outlook :) 

> -----Original Message-----
> From: Phil Bedard [mailto:philxor at gmail.com]
> Sent: vrijdag 20 april 2007 15:16
> To: jeff.tantsura at sscplus.nl
> Cc: 'Borchers, Mark M.'; juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] BGP Origin Issue
> 
> Yeah the Cisco is a little strange in those regards, the only time it
> will not
> use IGP for the origin code in an aggregate-address is if you are
> using as-set
> and one of the contributing routes is incomplete...
> 
> I second the policy of resetting the origin to IGP to take that out
> of the possible path selection.   Using a route-map on the
> redistribute, you
> can set that policy on import into the BGP table...
> 
> Phil
> 
> 
> On Apr 20, 2007, at 5:43 AM, Jeff Tantsura wrote:
> 
> > Hi,
> >
> > Actually there's a situation where you could get hit by differences in
> > "origin" setup.
> > By default Cisco, when aggregates, marks origin as IGP while
> > Juniper does
> > incomplete. If you have got more than 1 BGP sessions with a same
> > peer and
> > they aggregate on the peering routers where 1 is Cisco and another is
> > juniper... guess what :)
> > That's why resetting of origin to IGP on your borders is a good idea.
> >
> > Just my .02 cent
> > Jeff
> >
> >> -----Original Message-----
> >> From: juniper-nsp-bounces at puck.nether.net [mailto:juniper-nsp-
> >> bounces at puck.nether.net] On Behalf Of Borchers, Mark M.
> >> Sent: donderdag 19 april 2007 23:03
> >> To: 'juniper-nsp at puck.nether.net'
> >> Subject: Re: [j-nsp] BGP Origin Issue
> >>
> >> I'll apologize for posting a red herring to the list.  Looking
> >> further I
> >> believe that by diabolical coincidence, the origin-incomplete
> >> routes were
> >> also carrying prepends that prevented them from showing up as active
> >> routes
> >> anywhere.  The ones that were visible on the Internet were in some
> >> cases
> >> not
> >> prepended and in other cases more-specifics that weren't being
> >> announced
> >> elsewhere.  I jumped on the origin attribute too eagerly.
> >>
> >> Mark
> >>
> >>> -----Original Message-----
> >>>
> >>> Based on the fact that nobody has said "Yo dummy, JunOS never
> >>> re-advertises
> >>> prefixes with origin incomplete", I'm going to do more
> >>> detailed checking on
> >>> the looking glasses.
> >>
> >>
> >>
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> >>
> >>
> >>
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> 
> Phil Bedard
> philxor at gmail.com
> 
> 




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