From: Ronnie Royston (RonnieR@xxxxxxxxxxxxxxxxx)
Date: Mon Jan 08 2001 - 19:38:10 GMT-3
If you have:
IGRP OSPF
R1-------R2-------R3
Lo0 Lo0
1.1.1.1/24 2.2.2.2/24
You will not be able to get a routing loop using a dynamic routing protocol
unless you use the 'area range' command to get R2s OSPF to see 2.2.2.2 as
2.0.0.0/8 AND have no ip split horizon on both sides of your interfaces and
mutually redistribute OSPF/IGRP. (I'm using IGRP because RIP is higher in
admin weight than OSPF). To get your loop to kick in, use 'clear ip osp
redisribution'. Below is my homemade routing loop:
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
10.0.0.0/24 is subnetted, 1 subnets
C 10.2.2.0 is directly connected, Ethernet1
I 30.0.0.0/8 [100/1600] via 50.0.0.1, 00:00:11, Ethernet0
I 40.0.0.0/8 is possibly down, routing via 50.0.0.1, Ethernet0 ! LOOP.
C 50.0.0.0/8 is directly connected, Ethernet0
Router#
-----Original Message-----
From: Peter Van Oene [mailto:pvo@usermail.com]
Sent: Monday, January 08, 2001 12:34 PM
To: chuck@cl.cncdsl.com; ccielab@groupstudy.com
Subject: Re: OSPF Redistribution question
Hey Chuck,
I can't off top of my head see how you obtain a routing loop in a linear
network. With two points of redistribution (mutual redist if you like),
this becomes a fairly significant issue as I'm sure everyone here knows.
Maybe we're missing something.
*********** REPLY SEPARATOR ***********
On 1/7/2001 at 9:26 PM Chuck Larrieu wrote:
>I just complete a frenetic go-through of the Slattery/Burton book - chapter
>5 - OSPF section
>
>One section touches on redistribution between RIP 2 and OSPF ( although I
>suppose that is not necessarily relevant )
>
>In any case, setup was relatively simple:
>
>OSPF domain------redistribution_router----------RIPv2 domain
>
>Jus to see what happened, I failed to place the distribute-lists as
>recommended. I wanted to see bad thing happen. For the life of my I could
>net get a routing loop to form. I did things like lower the metric of the
>redistributed routes to below that of the native OSPF routes, hoping to see
>the RIP redistribution come into the routing tables of the OSPF routers. No
>dice.
>
>So my question - in a situation like the above, with only a single
>redistribution point, does it matter? Was the issue the particular routing
>protocols? Is the issue of redistribution and loops as a result relevant
>only with multiple redistribution points?
>
>Any thoughts as to why I couldn't cause problems when I tried, even though
I
>seem to have no trouble creating problems when I don't try?
>
>Chuck
>----------------------
>I am Locutus, a CCIE Lab Proctor. Xx_Brain_dumps_xX are futile. Your life
as
>it has been is over ( if you hope to pass ) From this time forward, you
will
>study US!
>( apologies to the folks at Star Trek TNG )
>
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