From: Perminder Grewal (percy_gunner@xxxxxxxxxxx)
Date: Fri Jul 26 2002 - 03:45:13 GMT-3
Tom good point, however thinking about it on this scenario . The
distributing router will have connected ospf and igrp routes in the route
table.
Tag igrp into ospf process and then deny tag back into igrp process.
Now the igrp routes are then passed onto say for example another router on
it's subnet running igrp. That router receiving the igrp routes will not
pass back those routes due to split horizons. So in this example a stub
network you should not get any route feedback.
The problem will arise when you have dual routers redistributing mutually
you will get route feedback, like in the NMC-1 final lab between rip and
ospf. Here you will have to use several methods ie distance and distribute
list or route-maps.
I think it all depends on the scenario in front off you.
Tom when did you do the NMC class? I went on it in March, a great class.
Regards
Percy
>From: "Tom Larus" <tlarus@cox.net>
>To: "Harish DV/peakxv" <harish.dv@peakxv.net>,"Perminder Grewal"
><percy_gunner@hotmail.com>
>CC:
><ccielab@groupstudy.com>,<Mark.Snow@newcome.com>,<nobody@groupstudy.com>
>Subject: Re: CCIE Practical Studies, Darth Reid, and Redistribution
>Date: Thu, 25 Jul 2002 17:40:31 -0400
>
>He tagged the IGRP and RIP routes as they were redistibuted INTO OSPF. I
>do
>this all the time.
>
>I like tagging to stop route feedback (at least one way) a lot, but it is
>not the cure-all. Caslow said in class that tagging is elegant and
>scalable, and taught us how to adjust the AD to prevent some unwanted
>results on the redistributing router (you know, from the routing protocol
>with lower AD taking over all the routes on teh router as its own)
>
>That made me feel better about using tagging, but the problem is that this
>one-way tagging does not stop an OSPF route that was redistributed into
>IGRP
>from being redistributed back into OSPF. I have not figured how big a
>problem this except, that it was deadly the other day when IGRP shortened
>the prefix and then redistributed an originally-OSPF route back into OSPF.
>The underlying problem was that split horizon needed to be disabled on a
>router in the IGRP domain. (That experience has been discussed to death
>here).
>
>I wish someone could assure me that one-way tagging, with appropriate
>distance adjustment, is adequate. I think I will need to get more practice
>doing redistrubution with distribute-lists, which seems to be the more
>well-established way of prventing route-feedback. Granular control is more
>important in the lab exam than scalability and elegance (or redundancy,
>even). I am scared to death of missing or fat-fingering a network number,
>though.
>
>
>----- Original Message -----
>From: "Harish DV/peakxv" <harish.dv@peakxv.net>
>To: "Perminder Grewal" <percy_gunner@hotmail.com>
>Cc: <ccielab@groupstudy.com>; <Mark.Snow@newcome.com>;
><nobody@groupstudy.com>
>Sent: Thursday, July 25, 2002 2:02 PM
>Subject: Re: CCIE Practical Studies, Darth Reid, and Redistribution
>
>
> > Percy,
> >
> > As far as I know, IGRP and RIPV1 don't support tags.Pls correct me if I
>am
> > wrong
> >
> > Harish
> >
> >
> >
> >
> >
> > "Perminder
> > Grewal" To:
>Mark.Snow@newcome.com, ccielab@groupstudy.com
> > <percy_gunner@hot cc:
> > mail.com> Subject: Re: CCIE
>Practical Studies, Darth Reid, and Redistribution
> > Sent by:
> > nobody@groupstudy
> > .com
> >
> >
> > 07/25/2002 09:56
> > AM
> > Please respond to
> > "Perminder
> > Grewal"
> >
>
> >
> >
> >
> >
> >
> > Mark
> >
> > Don't worry too much about the lab. I did it this week and it has too
>many
> > mistakes, infact it is the worst lab I have ever done.
> >
> > Concentrate on the routing issues as feel this is where you seem to be
>weak
> >
> > on, judging by your mail.
> >
> > On this lab I a tagged all the routes from the igrp & rip domain into
>the
> > OSPF domain so those E2 extarnal routes will be asociated a tag no.
> >
> >
> > Do sh ip ospf databse
> >
> >
> > I use tag 11 from IGRP to OSPF on router 1 and tag 33 from rip to ospf
>on
> > router 3.
> >
> > So when you redistrbute ospf back into IGRP and RIP use a route-map to
>deny
> >
> > those tagged routes back in there respective routing domain.
> >
> > I feel tags is nice and easy, however for rip into igrp or vice versa
>you
> > cannt use tags and will have to define an access-list and then use
> > distribute-list.
> >
> > Have a look at doyles vol 1 he has some good examples. I've pasted an
> > example below from darth reid.
> >
> > R1
> >
> > router ospf 1
> > router-id 133.10.1.1
> > redistribute igrp 1 subnets tag 22
> >
> >
> > router igrp 1
> > redistribute ospf 1 route-map ospf_2_igrp
> >
> > route-map ospf_2_igrp deny 10
> > match tag 22
> >
> > route-map ospf_2_igrp permit 20
> > set metric 1000 100 255 1 1500
> >
> >
> > R3
> >
> >
> > router ospf 1
> > router-id 133.10.3.3
> > redistribute rip subnets tag 33
> >
> >
> > router rip
> > redistribute ospf 1 route-map ospf_2_rip
> >
> >
> > route-map ospf_2_rip deny 10
> > match tag 33
> > !
> > route-map ospf_2_rip permit 20
> > set metric 2
> >
> >
> >
> >
> > Percy
> >
> >
> > >From: "Snow, Mark" <Mark.Snow@newcome.com>
> > >Reply-To: "Snow, Mark" <Mark.Snow@newcome.com>
> > >To: ccielab@groupstudy.com
> > >Subject: CCIE Practical Studies, Darth Reid, and Redistribution
> > >Date: Thu, 25 Jul 2002 11:31:00 -0400
> > >
> > >All -
> > >
> > >I am having difficulties with Section V of the Lab Practice exam "Darth
> > >Reid" in Solie's book, CCIE Practical Studies Volume 1.
> > >I have completed the Lab, and for the most part gotten all the parts to
> > >work, and have downloaded the answer PDFs from the CiscoPress web site.
> > >
> > >I really do not agree with some of the solutions that they give for
>this
> > >specific lab, and was wondering if anyone had any insight (maybe
>someone
> > >who
> > >has taken this practice lab) as to why they answer the way they do.
> > >Also does anyone have any really good ref material (links) for
> > >redistribution?
> > >
> > >Specifically, the answer PDF has most of the routing protocols ALL
> > >redistributing into each other, (OSPF into IGRP, and IGRP into OSPF,
>OSPF
> > >into EIGRP, and EIGRP into OSPF) (even OSPF into RIP on router R3 when
> > the
> > >lab specifically states NOT to advertise Lab routes onto the backbone -
>so
> > >there is no need for this).
> > >I am also getting a lot of routing loops due to this and right now I am
> > >clueless.
> > >
> > > > Mark Snow
This archive was generated by hypermail 2.1.4 : Sat Sep 07 2002 - 19:36:45 GMT-3