From: David Redfern \(AU\) (David.Redfern@didata.com.au)
Date: Sat Jul 15 2006 - 13:22:38 ART
Guys,
I just wanted to point out that the below scenarios are from
Internetwork Expert (fantastic I must add) practice labs which I am
using and not from the REAL lab.
I have not sat the lab yet. Looking at 2 months time. Wish me luck!
The below scenario come up over and over again in these practice labs
and I have not been able to find any consistency in the answers.
Usually the suboptimal routing issue is resolved yet sometimes tags are
used and other times not.
Thought maybe I'm missing something and want to get my head around it!
To all,
Just wondering what everyone would do in the below scenarios when in the
lab. Question of Best Practice vs Lab requirements.
Scenario one:
You have 2 points of mutual redistribution between ospf and eigrp You
have other external routes also coming into both protocols. (maybe from
rip or loopbacks redistributed ect)
Lab question askes you to configure redistribution between ospf and
eigrp at the 2 points.(does not mention anything about optimal routing
ect)
Now in the above scenario the external eigrp routes from rip (admin
170) once redistributed into ospf (admin 110) at one of the 2 points
will be chosen as the best path at the second point of redistribution,
causing suboptimal routing.
This can be resolved by tweaking the admin distances. There is also the
possibility of routing loops forming if no method of route feedback
prevention (such as filtering on tags) is used.
If the question does not ask you to provide optimal routing or anything
else should you
A) Tweak the admin distances where necessary to provide optimal routing
B) Don't do anything as you were not explicitely asked to do so and
have thereform accomplished the requirements of the question.
C) Ask the proctor
In regards to the route feedback issue should you
A) Use tag filtering to prevent routes redistributed from eigrp into
ospf from having the potential to be advertised back into eigrp at the
second point, and visa versa.
B) Don't do anything as you were not asked to.
C) Ask the proctor
Scenario two:
You are asked to advertise an aggregate bgp route of your internal
address space to the backbone. This aggregate also is sent back to your
internal network by default.
Should you
A) Filter the aggregate route from being sent back into your network
B) Don't do anything as you were not asked to
C) Ask the proctor
Regards,
David Redfern
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