From: Chris Lewis \(chrlewis\) (chrlewis@cisco.com)
Date: Sat Jul 16 2005 - 09:16:23 GMT-3
I'll try.....
Start off thinking about an OSPF domain and an EIGRP domain connected at
two points, say R1 and R2. Mutual redistribution occurs between OSPF and
EIGRP at both points. Do you need to perform any filtering to stop route
feedback? No, the reason is EIGRP has the concept of a separate
administrative distance for external routes. If it did not have that, a
route learned on R1 from OSPF would be fed in to EIGRP and from there
EIGRP would tell R2 about the route with a lower administrative distance
than OSPF, making R2 think that going back in to the EIGRP domian would
be a better route than going towards the OSPF domain. Potentially the
reverse operation could happen with the same OSPF route being learned on
R2 and it telling R1 about it via EIGRP causing a loop.
EIGRP never falls in to this trap because of the administrative distance
of external routes being 170, so any EIGRP originated route will be
preferred over a route redistributed in to OSPF on R1 and R2, as EIGRP
has a lower internal administrative distance, likewise R1 and R2 will
prefer any route learned from the OSPF domain over those redistributed
in to EIGRP as the AD of 170 is higher than OSPF.
If you consider an OSPF and RIP domain connected together, there is no
default high AD for OSPF external routes to stop the route feedback
happening. However, if you give OSPF externals an AD of say 180, it
behaves the same as EIGRP and you don't need to filter between the two
domains.
Chris
-----Original Message-----
From: cacca mucca [mailto:caccamucca@hotmail.com]
Sent: Friday, July 15, 2005 9:27 PM
To: jjrinehart@hotmail.com; Chris Lewis (chrlewis);
ccielab@groupstudy.com
Subject: Re: LAB study guide
Can you provide us with an example of the "distance ospf external to
stop routes feeding back" ?
Thanks
>From: "Joe Rinehart" <jjrinehart@hotmail.com>
>Reply-To: "Joe Rinehart" <jjrinehart@hotmail.com>
>To: "Chris Lewis (chrlewis)" <chrlewis@cisco.com>,
><ccielab@groupstudy.com>
>Subject: Re: LAB study guide
>Date: Fri, 15 Jul 2005 08:45:08 -0700
>
>Agreed on the redistribution answers. There are several ways to answer
>something, especially since the real test was whether or not ot
>achieved the desired result.....
>
>----- Original Message -----
>From: "Chris Lewis (chrlewis)" <chrlewis@cisco.com>
>To: "Joe Rinehart" <jjrinehart@hotmail.com>; <ccielab@groupstudy.com>
>Sent: Friday, July 15, 2005 8:38 AM
>Subject: RE: LAB study guide
>
>
>My opinion, FWIW is that they both have a lot of value to offer, DoiT
>more for the routing scenarios, Internetworkexpert more for the
>security and services side.
>
>I would add though that I often created simpler solutions to the NMC
>answer keys, particularly regarding the redistribution scenarios. I
>found it easier to use things like distance ospf external to stop
>routes feeding back, rather than setting up lots of specific route
filters.
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Joe Rinehart
>Sent: Friday, July 15, 2005 10:27 AM
>To: ccielab@groupstudy.com
>Subject: Re: LAB study guide
>
>Well I used the DoIT lab workbook and had great results, what exactly
>was out in left field? The thing that drove me crazy was
>redistribution, DoIT would have at least three to four redistribution
>points on each lab and you had to be really really careful about how
>you filtered....
>
>Joe Rinehart
>CCIE #14256, CCNP, CCDP
>Data Network Consultant
>AT&T Pacific Northwest Enterprise Markets
>----- Original Message -----
> > On 7/14/05, cacca mucca <caccamucca@hotmail.com> wrote:
> > > I'm using the DOiT lab and it is out in the left field. I should
> > > have
>bought
> > > the InterNetwork Expert. I even had an upgrade coming, but went
> > > with
>DOiT.
> > > Kicking myself now.
> > >
> > > Just my 2 cents
> > >
> > > >From: "Hooman Parta" <hooman@voipsol.com>
> > > >Reply-To: "Hooman Parta" <hooman@voipsol.com>
> > > >To: <ccielab@groupstudy.com>
> > > >Subject: LAB study guide
> > > >Date: Thu, 14 Jul 2005 10:22:12 -0500
> > > >
> > > >Hi,
> > > >
> > > >I just started my LAB preparation and got my LAB already. Does
> > > >any one recommend any of the LAB preparation materials. There are
> > > >several
>compaies
> > > >with differnt options. NLI, IPEXPERT, IE, InterNetwork expert and
> > > >much more.
> > > >
> > > >I know I should look for updated material which reflects the IPv6
> > > >and
>12.2T
> > > >but which one do you think is better to start?
> > > >
> > > >Thanks,
> > > >Hooman Parta
> > > >
> > > >_________________________________________________________________
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