From: Yves@xxxxxxxxx
Date: Thu Dec 27 2001 - 12:37:35 GMT-3
----- Forwarded by Yves Fauser/User/Goetze on 27.12.2001 16:28 -----
Yves Fauser
27.12.2001 14:43
To: Annu <annu_roopa@yahoo.com>
cc:
Subject: Re: OSPF route Selection ?
Annu,
I'm not able to reconstruct your problem in a Lab, but the reason should
be that OSPF prefers and Intra-Area path more than an Inter-Area path.
On R5 your path through R4 is a Intra-Area path, your path through R9 is
an Inter-Area path. I think thats why the higher metric path is choosen.
Try putting the Ser1's of R5 and R9 from Area 1 to Area 0, and look if the
path trough R4 is choosen then.
Reference : Jeff Doyle, Routing TCP/IP Vol.1, Page 490
Good luck,
Yves
Annu <annu_roopa@yahoo.com>
Sent by: nobody@groupstudy.com
27.12.2001 02:46
Please respond to Annu
To: ccielab@groupstudy.com
cc: annu_roopa@yahoo.com
Subject: OSPF route Selection ?
Group,
This is something i am unable to interpret.IF someone
can tell me why this is happening ? Here goes the
scenario.
e0 e0 s0
R9------------------R11------R10--20.1.1.1
| <-area 0 ---------> |s1
s1 | |
R5------------------R4-------|
e0 e0 s1
R9/R5 are ABR's and connected to R11/R4( both ASBR's)
E0 of both in area 0; Ser1 of ABR's in area 1.
R10 is connected to loopback 20.1.1.1.
R4 introduces type E1 route into R5.
R11 introduces type E1 route into R9.
Cost of E0 on R5=200;all other interfaces have default
cost.
Now R5 gets two E1 routes,one with cost 220(200+20)
from R4 and other with cost 94(64+10+20)from R9.
I thought the E1 route thru R9 and R11 will be the
preferred path as its same type and lower metric but
R5 seems to go thru R4.
Am i wrong in understanding ? or what is missing ?
Here are the route tables:
r5#show ip route
55.0.0.0/16 is subnetted, 1 subnets
C 55.1.0.0 is directly connected, Serial1
O E1 20.0.0.0/8 [110/220] via 172.16.1.18, 00:03:11,
Ethernet0
172.16.0.0/28 is subnetted, 1 subnets
C 172.16.1.16 is directly connected, Ethernet0
192.168.1.0/28 is subnetted, 2 subnets
O E1 192.168.1.0 [110/220] via 172.16.1.18,
00:03:11, Ethernet0
O E1 192.168.1.16 [110/220] via 172.16.1.18,
00:03:11, Ethernet0
When Ethernet fails ?
r5#show ip route
Gateway of last resort is not set
55.0.0.0/16 is subnetted, 1 subnets
C 55.1.0.0 is directly connected, Serial1
O E1 20.0.0.0/8 [110/94] via 55.1.1.2, 00:00:23,
Serial1
172.16.0.0/28 is subnetted, 1 subnets
O IA 172.16.1.0 [110/74] via 55.1.1.2, 00:00:23,
Serial1
192.168.1.0/28 is subnetted, 2 subnets
O E1 192.168.1.0 [110/94] via 55.1.1.2, 00:00:23,
Serial1
O E1 192.168.1.16 [110/94] via 55.1.1.2, 00:00:23,
Serial1
=====
Thanks in advance for ur time and replies.
Annu.
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