From: shiran guez (shiranp3@gmail.com)
Date: Thu Sep 27 2007 - 14:18:28 ART
as far as make better route a shorter prefix match, I think that practical
you cant unless you remove the longer prefix.
because ALWAYS a longer prefix is better.
On 9/27/07, Gregory Gombas <ggombas@gmail.com> wrote:
>
> Ben - I think Step 1 is correct but not step 2. As Cecil said ebgp has AD
> of 20.
>
> Now since it prefers the locally originated route it ignores the BGP
> route.
>
> Step 2 would be to look where that locally originated route came from,
> in this case RIP, and then use the rip route.
>
> So only the RIP route makes it to the routing table. I guess BGP is
> smart enough to say that I'm not sending the locally originated BGP
> route to the route table because it should already be in the route
> table by some other source (protocol,connected,static, etc...)
>
> Hopefully some CCIE's will put their 2 cents here...
>
> On 9/27/07, Cecil Wilson <Cecil.Wilson@flextronics.com> wrote:
> > Seems a little confusing
> > 1. locally origin routes will be select oover ebgp however in terms
> > of AD
> > EBGP 20
> > IBGP 200
> > RIP 120
> >
> > So in terms of AD external BGP routes should be selected over IBGP?
> >
> > Im I looking at it wrong?
> >
> >
> > Cecil G. Wilson
> > IT Network Services
> > Office: (901) 215-2710
> > Cell: (901) 601-6201
> > cecil.wilson@flextronics.com
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > Ben
> > Sent: Thursday, September 27, 2007 10:23 AM
> > To: Gregory Gombas
> > Cc: Cisco certification
> > Subject: Re: RIP is preferred over eBGP!
> >
> > Gregory,
> >
> > Step 1: Router B is faced with two BGP sources, ebgp and locally
> > originated (redistributed from RIP).
> >
> > BGP decision process will pick the locally originated over the ebgp
> > route (Wendel Odom)
> >
> > W - weight
> > L - local preference
> > L - locally originated
> > A - AS path
> >
> > O - Origin
> > M - MED
> > N - Neighbor Type
> > I - cannot remember :)
> >
> >
> > Step 2: BGP administrative distance for locally originated is 200, for
> > RIP 120. RIP therefore wins.
> >
> > In case I've got the sequence figured out wrongly, comments are welcome.
> >
> > Ben
> >
> >
> >
> >
> >
> >
> > On 9/26/07, Gregory Gombas <ggombas@gmail.com> wrote:
> > >
> > > I'm seeing the following quirk in a production network:
> > >
> > > BGP-->
> > > RIP-->
> > > RTRA----------RTRB
> > >
> > > Router A is directly connected to router B and is sending the same
> > > routes via RIP and eBGP.
> > > Router B is also redistributing the RIP routes into BGP (but filtered
> > > from sending back to A)
> > >
> > > When you look at the route table on RouterB, it shows the routes as
> > > RIP routes!
> > > You would think the eBGP learned routes would be preferred because of
> > > lower AD.
> > > But when I look at BGP table it shows the route originated locally and
> >
> > > thus preferred over eBGP learned route.
> > > When I clear ip route the route is then shown as a eBGP route in the
> > > routing table and BGP route table does not show the locally originated
> >
> > > route!
> > >
> > > Just wondering if anyone else has seen this...
> > >
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-- Shiran Guez MCSE CCNP NCE1 http://cciep3.blogspot.com
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