From: Sam Munzani (sam@xxxxxxxxxxx)
Date: Wed Nov 08 2000 - 11:34:53 GMT-3
To create loop you have to have more than one router configured.
Following will create a loop.
R1--- R2
| /
| /
R3
|
R4--- R5(192.168.100.0)
R4-R5 runs RIP, R1-R2 OSPF, & R3 runs both and does redistrubution
both ways.
This is what happens,
The network 192.168.100.0 from R5 is known to R3 by RIP. It
redistributes to OSPF. Now R1 learns about that network 192.168.100.0
from R3 via OSPF because of redistribution. It will pass that
reachability information to R2. Now R2 will tell R3 about
192.168.100.0 is reachable from it. R3 will believe R2 better than R4.
So it will scrap out RIP route learned from R4 and put reachability
information for 192.168.100.0 via R2. There you got your loop.
Apply route-maps to avoid any LSA type-5 out of OSPF database.
Distribution-lists will work also but it will not prevent it showing
up in ospf database. It will just prevent from routing table.
Sam
----- Original Message -----
From: zhangxianqi
To: David FAHED
Cc: zhang zhichao ; ccielab@groupstudy.com
Sent: Tuesday, November 07, 2000 8:38 PM
Subject: Re: ospf redis
in power session of beijing,the procotor present a slide and say this
will produce route loop and make ospf demand circuit flap,the slide is
like that:
router ospf 1
redistribute rip subnet
network 1.0.1.0 0.0.0.255 area 0
router rip
redistribute connected
default-metric 2
network 3.0.0.0
i try it,but can't produce loop,so what it mean? please the person who
attend the power session recall it and give me a answer,thanks in
advance.
----- Original Message -----
From: David FAHED
To: zhangxianqi
Cc: ccielab@groupstudy.com ; zhang zhichao
Sent: Tuesday, November 07, 2000 10:17 PM
Subject: Re: ospf redis
It is true with a distance vector protocol if ip split horiton is
turned off permanent routing loops can form in the internetwork.
But I think with link state protocol it is not possible.
zhangxianqi wrote:
hi allI hearded because the ospf have not split-horizen,so when
ospf and another igp do mutual redistribution,there maybe produce
route loop,but when I try it,I can't produce the loop.can someone
give me a example,thanks in advance.
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