From: Anthony Pace (anthonypace@xxxxxxxxxxx)
Date: Sun Jun 09 2002 - 21:36:11 GMT-3
The downside of the distribute lists is that networks can't really be
added behind the redist router (if you used permits in the
dist-list)They also destroy redundany accross multiple redistribution
points. Doyle describes a scenario where you don't block the routes
being fedback (perhaps form a second redist-router), but lower their AD
so they never make it into your routing table and thus are never
advertised beyond the redist router. If there is a failure somewhere
then these routes with their "inferior" AD will be prefered and go into
the table and once the network converges you have a redundent path.
Anthony Pace
On Sat, 8 Jun 2002 22:07:34 -0400, "Tom Larus" <tlarus@novacoxmail.com>
said:
> Yes. RIP does not carry tags. This tagging must be done as the routes
> are
> redistributed INTO a routing protocol that supports them. I see the
> problem, now, and that is that we still need to stop the OSPF routes
> that go
> into RIP or IGRP from feeding back into OSPF. For that I guess we need
> to
> use the old methods of blocking individual routes.
>
> Doyle I also indicated that distribute lists have their shortcomings,
> too,
> but it is too late for me to get teh book and cite the page. He had an
> explanation that I need to take a bit more time to think about and
> digest. I
> definitely need to do more work with this manipulating admin distance.
> The
> big problems seem to have to do with redistributed routes that have
> lower
> admin distance.
>
>
> ----- Original Message -----
> From: "Treptow, Georg" <gxtrept@qwest.com>
> To: "'Tom Larus'" <tlarus@novacoxmail.com>; "Anthony Pace"
> <anthonypace@fastmail.fm>; "Dennis Laganiere"
> <dennisl@advancedbionics.com>;
> "'Paul Connelly'" <chewy7700@yahoo.com>; <ccielab@groupstudy.com>
> Sent: Saturday, June 08, 2002 9:42 PM
> Subject: RE: OSPF tags as a way to stop route feedback from
> redistribution--
> what is the downside?
>
>
> > This unfortunatly is not an answer but more of an extension to Tom's
> > question.....
> >
> > I have recently done a lot of work on tagging, one of my scenarios that I
> > tried did not work out that great..
> >
> > R1--------------R6----
> > RIP v.1 |
> > | OSPF
> > R10--|
> > |
> > R4--------------R13---
> >
> > R1,R4 are redistribution routers between RIP v.1 and OSPF, R10 runs RIPv.1
> > only. R6 and R10 OSPF only.
> >
> > I thought to myself that there has to be a better way of redistribution
> from
> > RIP to OSPF and vice versa.
> > Instead of doing distribute/prefix lists I tagged all routes going into
> the
> > RIP domain (from OSPF) at R1 with 1111 and R4 I used 4444.
> > At R1 I declared all routes with a tag of 4444 to be dismissed from
> > redistribution back into OPSF and at R4 i did the same blocking all routes
> > with a tag of 1111 but allowing all others. For whatever reason all routes
> > from the RIP domain were blocked.
> >
> > Is it possible that RIP gets rid of tag information? Am I missing
> something
> > here?
> >
> >
> > Thanks,
> >
> > Georg Treptow
> >
> >
> >
> > -----Original Message-----
> > From: Tom Larus [mailto:tlarus@novacoxmail.com]
> > 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!?
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This archive was generated by hypermail 2.1.4 : Tue Jul 02 2002 - 08:12:30 GMT-3