From: Rik Guyler (rik@guyler.net)
Date: Tue Feb 12 2008 - 19:36:30 ARST
Hmmm...maybe but I would think this level of BGP understanding would be more
for the SP track than R/S. Definitely agree that you have to know what MED
is, how to use it and how to configure it if needed in the lab but the
underlying theory about route leakage and the such may be over the top for
R/S IMHO. Optimal routing has never been a focus in the lab.
Rik
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Jersey Guy
Sent: Monday, February 11, 2008 9:24 PM
To: Cisco certification
Subject: can't understand BGP Theory
From Halabi's book, Internet Routing Architectures, 2nd edition, page 167:
*MEDs are somewhat handicapped by aggregation scenarios in which providers
announce a given CIDR block from multiple locations in their network and
suppress the smaller routes from the block. Utilizing MEDs in this scenario
could potentially result in suboptimal routing because the more-specific
routes of the CIDR block could be scattered throughout the AS and MEDs
associated with more-granular routes are no longer available.
When using MEDs to perform what's commonly referred to as best-exit routing,
some providers leak the more-specifics of their CIDR blocks to select peers
to remove the offshoots introduced by aggregation. The problem with this is
that controlling the more-specific announcements is sometimes complex, and
failure to do so can result in some very suboptimal routing situations.
*
I read the above two paragraphs five times but didn't understand it. Which
of the following is true:
a) I have no choice but to understand this stuff, to pass the lab. I need to
understand *everything* in Halabi's book, period.
b) The lab is tough but not THAT tough. I can skip certain convoluted
sections of every topic and still manage to get by.
c) Forget it. I am not going to make it. MED is a piece of cake; what's so
hard to understand??
d) I need to read "How to grow gray matter and raise IQ" book before
Halabi's.
Thing is....how thoroughly do I need to pound away at theory/reading before
hitting the equipment, lab scenarios and excercises?
thanks, JG
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