From: Johnny Dedon (johnny.dedon@xxxxxxxxxx)
Date: Fri Mar 02 2001 - 11:41:30 GMT-3
I haven't tested this yet so Chuck you can provide your results, but this is
my opinion. A given router will put the route with the least cost to the
destination in its routing table if it has different entries from the same
routing protocol. Depending on the which router you look at you may have
the E1 route on one and an E2 route on another. The E2 route will have the
fixed cost so it will be preferred in most cases and this is why when
redistributing into OSPF when not careful you can get sub-optimal routes to
the destination when multiple exit points exist.
My take on things...
Johnny Dedon
Senior Staff Consultant
Exodus Professional Services
johnny.dedon@exodus.net
www.exodus.net
----- Original Message -----
From: "fwells12" <fwells12@hotmail.com>
To: <ccielab@groupstudy.com>
Sent: Friday, March 02, 2001 2:35 AM
Subject: Re: Friday Follies Returns - OSPF route preference
> In Tom Thomas' Cisco Press book 'OSPF Network Solutions Design Guide' is
> says exactly the opposite!! IE: a type 2 route is always preferred to a
> type one route to the same destination. Type 1 routes are those which
have
> their costs incremented as they cross the network. I would hazzard a
guess
> that on that basis alone they would be preferred due to the likelyhood of
> them reflecting more accurate costs.
>
> ----- Original Message -----
> From: Frank Jimenez <franjime@cisco.com>
> To: <ccielab@groupstudy.com>; Chuck Larrieu <chuck@cl.cncdsl.com>
> Sent: Thursday, March 01, 2001 10:20 PM
> Subject: Re: Friday Follies Returns - OSPF route preference
>
>
> > Chuck,
> >
> > As fate would have it, I was just pondering the same thing at a customer
> site a few days ago.
> >
> > The answer is a), given that the routes are both for the same
destination.
> >
> > From: http://www.cisco.com/warp/public/104/3.html under the heading 'E1
> vs. E2 External Routes'
> >
> > "A type 1 route is always preferred over a type 2 route for the same
> destination."
> >
> >
> > Frank Jimenez, CCIE #5738
> > franjime@cisco.com
> >
> >
> >
> >
> > At 10:06 PM 03/01/2001 -0800, you wrote:
> > >A less fun reprise of my once famous Friday Follies questions:
> > >
> > >Given the following information, which route will ospf prefer, and
> therefore
> > >place into the routing table?
> > >
> > >a) E1 ( external type 1 ) with a cost of 84
> > >b) E2 ( external type 2 ) with a cost of 20
> > >
> > >For extra credit - why?
> > >( I don't know either and I can't find a good explanation on the doc
CD )
> > >( but this time I have traces and captures to prove the point )
> > >
> > >Chuck
> > >----------------------
> > >I am Locutus, a CCIE Lab Proctor. Xx_Brain_dumps_xX are futile. Your
life
> as
> > >it has been is over ( if you hope to pass ) From this time forward, you
> will
> > >study US!
> > >( apologies to the folks at Star Trek TNG )
> > >
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