RE: Reg Experts!

James,

The first will deny only if the last AS in the path was 200
The second will deny if in the path 200 and originated in 300 but may have
additional AS's as well first.
The first one only allows two AS

The third will allow either 1 AS in the path or Null (Meaning local AS
prefixes.)
The fourth will match if 1 AS is in the path or if 1 AS plus the as 1 as the
originator in the path

The fifth is an AS that begins with 100 and has any numbers after it.
The sixth is the same as the third

Regards,
 
Tyson Scott - CCIE #13513 R&S, Security, and SP
Managing Partner / Sr. Instructor - IPexpert, Inc.
Mailto: tscott_at_ipexpert.com

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
Poplawski, James
Sent: Wednesday, June 09, 2010 1:19 PM
To: 'ccielab_at_groupstudy.com'
Subject: Reg Experts!

Just going through Narbik's Regular Expression listings and using INE
"Understanding BGP Regular Expressions" for reference.

I have some questions if anyone can explain in people terms. Here goes.

What's the difference between?
       deny ^200_300$
       deny _200_300$

       ^([0-9]+)?$
       ^([0-9]+)(_1\)*$

       _100+
       ^([0-9]+)(_\1)*$

In regards to ^([0-9]+)(_\1)*$ why is the number 1 chosen? Why have it at
all? Why not have a 0 or a 2 in there? I'm still looking through
documentation on \.

Any help is appreciated, thanks!
JB

This transmission contains information for the exclusive use of the intended
recipient and may be privileged, confidential and/or otherwise protected
from disclosure. Any unauthorized review or distribution is strictly
prohibited. Our company is required to retain electronic mail messages,
which may be produced at the request of regulators or in connection with
litigation. Electronic messages cannot be guaranteed to be secure, timely or
error-free. As such, we recommend that you do not send confidential
information to us via electronic mail. This communication is for
informational purposes only and is not an offer or solicitation to buy or
sell any investment product. Any information regarding specific investment
products is subject to change without notice. If you received this
transmission in error, please notify the sender immediately by return e-mail
and delete this message and any attachments from your system.

Blogs and organic groups at http://www.ccie.net
Received on Wed Jun 09 2010 - 15:11:57 ART