From: Michael Snyder (msnyder@xxxxxxx)
Date: Sat Jun 08 2002 - 23:07:19 GMT-3
Tags are cool.
I would guess like anything else you do, you should know at least two,
if not three different ways to do it.
I think the downside would be if the lab requirement said not to use
them.
Note, this might not be as bad as it seems. For example tonight I'm
doing a lab with ospf-->eigrp and eigrp-->ospf.
Using tags worked like a charm.
But what if they wasn't allowed. Well, from eigrp, the ospf
redistribute command you have a choice which routes to match.
A(config-router)#redistribute ospf 1 match ?
external Redistribute OSPF external routes
internal Redistribute OSPF internal routes
nssa-external Redistribute OSPF NSSA external routes
And I know all the routes I put into OSPF from EIGRP will be the
external type. So if I only import internal routes back into EIGRP, I
know I won't have route feedback. That's without using tags or a long
distribute list.
Of course, if there are external routes I need from OSPF, I'll have to
use a different method.
My rule of thumb is; if it's in the IOS, it's fair game to use.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Tom Larus
Sent: Saturday, June 08, 2002 8:21 PM
To: Anthony Pace; Dennis Laganiere; 'Paul Connelly';
ccielab@groupstudy.com
Subject: OSPF tags as a way to stop route feedback from redistribution--
what is the downside?
I'd like to ask about the downside of another approach that seems too
good
to be true. In doing practice labs, I like to tag routes from other
protocols as they are redistributed into OSPF (for example, tag routes
from
IGRP 120 with tag 120), then have a route-map that stops those routes
from
going back into the other protocol. The problem is that one does not
see
this in case studies or in practice lab solutions very often, and that
makes
me nervous. Doyle I contains a reference to this use of tags in the
chapter
on route-maps, and that makes me feel a little better.
This has the feel of something that seems neat but is very dangerous.
Basically, anything that does involve manually typing in half the routes
in
my network feels wrong, because it is not the tedious method that
involves
as much typing of routes as possible and nailing things down manually.
--- Original Message -----
From: "Anthony Pace" <anthonypace@fastmail.fm>
To: "Tom Larus" <tlarus@novacoxmail.com>; "Dennis Laganiere"
<dennisl@advancedbionics.com>; "'Paul Connelly'" <chewy7700@yahoo.com>;
<ccielab@groupstudy.com>
Sent: Saturday, June 08, 2002 8:01 PM
Subject: OSPF into IGRP and summarizing into FLSM
> Tom Larus said "Let's say you have loopback addresses on OSPF enabled
> routers that you will need to summarize so that an IGRP /24 network
> will be able to see them and reach them. You redistribute them into
> OSPF, and use summary-address ip mask to summarize them right there on
> the same router, which is by definition an ASBR because redistribution
> is happening on it. Works like a charm."
>
> In other words you are using IP SUMMARY under OSPF even though you
want
> to shoot the /24 into IGRP? Then, a /24 is created right there on that
> router and puhed into the IGRP world? Is that correct?
>
> I have been looking at this list for a definitive answer on this for a
> while (not wanting to repost a question if it has allready been
> answered) This seems like a solution. The quesion has been asked many
> times and interpreted or missinterpreted differently in different
posts
> but essentially this is the problem as I see it: All of the protocoles
> on the LABS we have all been doing have a mechanism for redistributing
> and controlling summarization except IGRP. The LABS almost always give
> you the ability to summarize almost all your networks via these other
> mechanisms long before they reach the OSPF/IGRP redistribution point
> with the exeption of a loopback or directly connected network on that
> router which does not conform to the IGRP FLSM. It has been suggested
> that a "ip default-network" be shot into IGRP and this works but it is
> questionable as to weather this constitutes an ILLEGAL STATIC ROUTE.
> The Solie labs pose this scenario but the soltions do not address it.
>
> Are there any other tools that can be used?
>
> Anthony Pace
>
>
>
> On Tue, 4 Jun 2002 13:35:53 -0400, "Tom Larus"
<tlarus@novacoxmail.com>
> said:
> > I have never taken the lab, so I could not speak to that aspect of
the
> > question, but I did learn something recently I thought was neat, but
> > that
> > many others here have probably known for years.
> >
> > Let's say you have loopback addresses on OSPF enabled routers that
you
> > will
> > need to summarize so that an IGRP /24 network will be able to see
them
> > and
> > reach them. You redistribute them into OSPF, and use
summary-address
> > ip
> > mask to summarize them right there on the same router, which is by
> > definition an ASBR because redistribution is happening on it. Works
> > like a
> > charm.
> >
> > Okay, it's old hat for a lot of you old hands, but I still think it
is
> > pretty neat.
> >
> >
> > ----- Original Message -----
> > From: "Dennis Laganiere" <dennisl@advancedbionics.com>
> > To: "'Paul Connelly'" <chewy7700@yahoo.com>;
<ccielab@groupstudy.com>
> > Sent: Tuesday, June 04, 2002 12:40 PM
> > Subject: RE: Connected routes vs network statement
> >
> >
> > > Some routing protocols will interpret the two differently. EIGRP,
or
> > > instance, will see the redistributed route as external, which has
a
much
> > > higher AD.
> > >
> > > --- Dennis
> > >
> > >
> > > -----Original Message-----
> > > From: Paul Connelly [mailto:chewy7700@yahoo.com]
> > > Sent: Tuesday, June 04, 2002 9:03 AM
> > > To: ccielab@groupstudy.com
> > > Subject: Connected routes vs network statement
> > >
> > > Is there a preference in the lab when to use "redistribute
connected"
vs.
> > > network statements? I know the redistribute connected will not
turn on
the
> > > routing protocol on the interface but you can easily turn it off
with
> > > passive-interface. Just want to check if the exam wants you to do
it a
> > > certain way.
> > >
> > >
> > >
> > > Thanks
> > >
> > >
> > >
> > > ---------------------------------
> > > Do You Yahoo!?
> > > Sign-up for Video Highlights of 2002 FIFA World Cup
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