From: David Luu (wicked01@xxxxxxxxxxxxx)
Date: Thu May 09 2002 - 17:05:54 GMT-3
igrp knows of the 2 other interfaces, so when you redistribute to ospf it
will know the networks as well and will appear in the routing table as O E1
or O E2 depending on which metric-type you are using
At 09:32 AM 5/9/2002 -0500, Kirby, Ron wrote:
>I have a lab from solie setup (darth reid) and I have igrp running on r1
>and ospf configured only on the serial and dialer interface. The
>133.10.0.0 address in igrp covers two other interfaces on that router that
>are not in the ospf process, and they are in the route table as
>connected. Yet, when I redistribute igrp into ospf, those connected
>routes show up in the table of other ospf routers. I thought they would
>not, but they are????
>
>Ron Kirby
>Network Engineer
>ICTC Engineering
>
>Getronics Infrastructure Solutions
>9009 West Loop South
>Houston, Texas 77096
>713-852-5567
>832-256-5403
>www.getronics.com/us
>
>
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>-----Original Message-----
>From: Joe Higgins [mailto:netsat@optonline.net]
>Sent: Thursday, May 09, 2002 9:02 AM
>To: ying chang
>Cc: ccielab@groupstudy.com
>Subject: Re: Redistribute ospf external route into igrp
>
>
>The way that redistribution appears to work to me is as follows.
>For example if you are redistributing ospf into igrp then on the
>redistribution
>router the IOS looks in its ip routing table and redistributes any routes that
>begin with an O in front of it into the igrp process. If you are
>redistributing
>rip into igrp it looks in its routing table and redistributes into igrp any
>routes with an R in front of it. The reason that connected routes in the ospf
>database and the rip process do not get redistributed into igrp is because
>they
>have a C (connected) in front of them in the routing table on the
>redistribution
>router. The rule that I use is that if it has a C in front, it is not
>going to
>be redistributed unless you redistribute connected. I welcome any comments to
>the contrary.
>
>ying chang wrote:
>
> > Sorry, found a few mistakes from my post below, but the basic concept
> > presented is correct. In short, an external route will not get
> redistributed
> > if it's also an internal route or a local routing process.
> >
> > Chang
> >
> > >From: "ying chang" <ying_c@hotmail.com>
> > >Reply-To: "ying chang" <ying_c@hotmail.com>
> > >To: ccielab@groupstudy.com
> > >Subject: RE: Redistribute ospf external route into igrp
> > >Date: Thu, 09 May 2002 00:32:51 -0400
> > >
> > >After went through a few tests, I don't think the issue is not on
> > >split-horizon but on whose route is more trustworthy:
> > >
> > >Since mutual redistribution is always causing confusion, and this problem
> > >can be simulated without mutual redistribution, so I set up an environment
> > >like the following:
> > >
> > > R4<--igrp---R3<---rip---R5--172.16.155.0/24
> > > |
> > > ospf
> > > |
> > > R1<--rip----R2--172.16.125.0/24
> > >
> > >and below is what I got:
> > >
> > >Two external routes in R3:
> > >
> > >r3#sio d | b -5 <<<- both 125.0/24 and 155.0/24 are in ospf external db
> > > Type-5 AS External Link States
> > >
> > >Link ID ADV Router Age Seq# Checksum Tag
> > >172.16.125.0 172.16.200.1 48 0x80000001 0xC013 12
> > >172.16.155.0 172.16.146.1 610 0x80000002 0x8E45 35
> > >
> > >Only 172.16.155.0 is redistributed into igrp:
> > >
> > >r3#debug ip igrp tra <<<--sending 125.0/24 but not 155.0/24
> > >IGRP protocol debugging is on
> > >r3#
> > >13:28:22: IGRP: sending update to 255.255.255.255 via Ethernet0
> > >(172.16.52.3)
> > >13:28:22: subnet 172.16.144.0, metric=501
> > >13:28:22: subnet 172.16.145.0, metric=501
> > >13:28:22: subnet 172.16.146.0, metric=501
> > >13:28:22: subnet 172.16.53.0, metric=1100
> > >13:28:22: subnet 172.16.10.0, metric=8476
> > >13:28:22: subnet 172.16.125.0, metric=158250 <<<<----
> > >r3#
> > >r3#sh ip rip data <<<- r3 has 155.0/24 but not 125.0/24
> > >172.16.0.0/16 auto-summary
> > >172.16.145.0/24 directly connected, Loopback1
> > >...
> > >172.16.149.0/24
> > > [1] via 172.16.10.1, 00:00:08, Serial0
> > >172.16.155.0/24 <<<<------
> > > [1] via 172.16.53.1, 00:00:09, Ethernet1
> > >...
> > >r3#
> > >
> > >I think the reason 172.16.155.0/24 was not sending to IGRP is because from
> > >R3's point of view, 172.16.155.0/24 is in its rip database (know it by
> > >first
> > >hand), it also knows 172.16.155.0/24 is in ospf - but that's learn from
> > >some
> > >other protocol (second hand stuff), so the route is not cannot be trusted,
> > >and that's why when you redistribute ospf into igrp, you only see R1's rip
> > >routes but not R4's rip routes. 172.16.125.0/24 did not have this problem,
> > >because it's not in R3's local rip database.
> > >
> > >The moral for this problem: when you run more than two protocols in a
> > >router
> > >like this, not only you have to redistribute ospf into igrp, you also need
> > >to redistribute directly connected rip routes into igrp.
> > >
> > >Chang
> > >
> > >>From: "Jenkins, Buddy" <buddy.jenkins@csfb.com>
> > >>Reply-To: "Jenkins, Buddy" <buddy.jenkins@csfb.com>
> > >>To: ccielab@groupstudy.com
> > >>Subject: RE: Redistribute ospf external route into igrp
> > >>Date: Thu, 9 May 2002 07:25:00 +0900
> > >>
> > >>Jeff,
> > >>
> > >>Refer to Doyle Volume1 Chapter 11 on redistribution. In the questions at
> > >>the end of the chapter there is a question (I don't have the book with me
> > >>right now so I can't tell you the specific question) that has the same
> > >>scenario that you have. Doyle says that the reason for that type of
> > >>behaviour is because of the rule of split horizon. This makes sense for
> > >>you scanario below because IGRP would use split horizon and OSPF does not
> > >>use split horizon. However this is the part that still confuses
> me. I do
> > >>not know why split horizon is applied to a redistribution process. I
> > >>always though split horizon was implemented to not advertise a route out
> > >>an
> > >>interface from which that route was learned. Can any of the guru's out
> > >>there explain why split horizon is applied during mutual redistribution?
> > >>
> > >>Buddy
> > >>
> > >>-----Original Message-----
> > >>From: Jeff Szeto [mailto:jytszeto@hotmail.com]
> > >>Sent: Wednesday, May 08, 2002 5:20 PM
> > >>To: ccielab@groupstudy.com
> > >>Subject: Redistribute ospf external route into igrp
> > >>
> > >>
> > >>Hi,
> > >>
> > >>A router runs IGRP, OSPF and RIP. Mutual redistribution exist between
> > >>OSPF---RIP and OSPF---IGRP. But no redistribution between IGRP and RIP.
> > >>From the debug message I found that IGRP is no advertising the RIP routes
> > >>that are redistributed into OSPF while the OSPF routes are advertised
> > >>normally.
> > >>On the other hand, the IGRP routes are advertised into RIP through OSPF.
> > >>
> > >>Could someone explain the concept behind or point me to a document.
> > >>
> > >>Thanks in advance.
> > >>
> > >>Jeff
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:58:53 GMT-3