From: Michael Snyder (msnyder@xxxxxxx)
Date: Thu Aug 15 2002 - 09:52:31 GMT-3
I'm no expert on as-path access-lists.
But, I believe the $ is the main difference.
^4_ anything beginning with as path 4.
^4_[0-9]*$ anything beginning with as path 4 and ENDS with one
additional AS.
Which brings up a question of mine,
Why wouldn't ^4_*$ do the same thing?
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Raj
Sent: Thursday, August 15, 2002 7:02 AM
To: ccielab@groupstudy.com
Subject: Filtering BGP updates using ip as-path access-lists
Hi all,
I've come across a scenario for which I require some clarification.
I want to permit only networks originated from AS4, and AS's directly
attached to AS4. I use the following config to meet the requirements,
however I have come across documentation that has achieved the same
results
using a slightly different version. I've listed both of them below:
ip as-path access-list 1 permit ^4_
and the other being:
ip as-path access-list 1 permit ^4_[0-9]*$
Could someone please help clarify why one method would be preferred over
the
other?
Thanks,
Raj.
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