From: Arun Arumuganainar (aarumuga@hotmail.com)
Date: Wed Sep 20 2006 - 08:22:02 ART
Hi Sabrina ,
When I look at your topology , I would say if you leave it to default it
would result in Asymmetric routing . Let me explain .
Here R1 is connected to SW1 via Fast-ethernet hence Cost = 1 ( Assuming cost
= 10power8/ BW )
R2 is connected to SW1 via ethernet hence Cost = 10 ( Assuming cost =
10power8/ BW )
Hence Correct design would mandate us to increase the cost on R1 !!! You can
work on two solution here a) Bandwidth 10000 or b) ip ospf cost 10 and these
configuration should be done R1 only !!!
Pls. Note : If R1 is directly connected to R2 , this problem would not have
arised at all in the first Place . Problem is due to the switch that sits in
between these two routers.
From Exam Point of view : The above discussion is purely based on optimal
routing consideration . In exams you would have to watch the wording
carefully. In my humble opinion, questions in CCIE lab would never be
ambiguous . If at all it is ambiguous we can always ask the proctor .
Thanks and Regards
Arun
----- Original Message -----
From: "sabrina pittarel" <sabri_esame@yahoo.com>
To: <ccielab@groupstudy.com>
Sent: Wednesday, September 06, 2006 9:18 AM
Subject: Q. on OSPF cost settings on interfaces with different speeds
> Hi,
> assuming I have the following topology:
>
>
> R1 -----------(SW)------------R2
> f0/0 e0/0
>
> with R1 and R2 running OSPF.
> Should I adjust the ip ospf cost on R1 to reflect R2's cost (or
viceversa)?
> Having a different cost on each side of the link may cause asymmetric
routing to happen (assuming a topology a little more complex than the one I
drew) and I wonder if it is required in the lab to have the two interface
costs matching.
>
> I believe that when a task explicitly requires to change the cost we have
to do it on both side (right?), wouldn't this be a similar case?
>
> Sabrina
>
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