BGP Regular Expression - logic help

From: Joe Deleonardo (Joe_Deleonardo@hotmail.com)
Date: Sun Jul 11 2004 - 21:09:33 GMT-3


Hi,

According to what I've read

* = 0 or more
+ = 1 or more
? = 0 or 1

Taken from:
http://www.cisco.com/univercd/cc/td/doc/product/atm/c8540/12_0/13_19/cmd_ref
/appc.htm#1003249

Then I see this example - taken from
http://www.cisco.com/warp/public/459/26.html#t5

^4_[0-9]*$ = AS 4 and it's directly attached ASs

It seems like this should match 4 or 4 + any AS (1 or more times) - in other
words to me this seems the same as this expression ^4 .*

The * seems to mean any number of occurrences >= 0

In other words, to me at least it seems like it should match 4 or 4 x or 4 x
y... etc.

It seems like ^4_[0-9]?$ would be what we should use to get "Only Networks
Originated from AS 4, and ASs Directly Attached to AS 4" No?

So what do you guys think? Am I over thinking this? Yes ^4_[0-9]*$ will get
you what you want but it seems like, you'll also get more then AS 4 and it's
directly attached networks.

You know if I had the choice of Cisco improving on any one thing - this
would be it. There's got to be an easier way to catch this mouse.

Thanks in advance!

Joe

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