From: Joe Higgins (netsat@xxxxxxxxxxxxx)
Date: Thu May 09 2002 - 14:54:01 GMT-3
I just set it up and you are right. The connected routes covered by irgp do g
o into ospf.
"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 pr
ocess, 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 route
rs. 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 redistributi
on
> router the IOS looks in its ip routing table and redistributes any routes tha
t
> begin with an O in front of it into the igrp process. If you are redistribut
ing
> 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 osp
f
> database and the rip process do not get redistributed into igrp is because th
ey
> have a C (connected) in front of them in the routing table on the redistribut
ion
> 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 t
o
> 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 redistribute
d
> > 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 d
o
> > >>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