From: David Buechner (dbuechn@attglobal.net)
Date: Mon Jun 14 2004 - 00:33:37 GMT-3
Actually, the regular expression you'd need would depend on where you
are. If you're configuring this regular expression on a router which is
*NOT* in AS100 then you would want to use the following:
^100(_[0-9]*)?$
This is because the path is prepended (i.e. the AS path is in reverse
order) and the 100 would be first. An example use of this would be to
filter updates coming into AS300 in such a way that you only accept routes
for AS100 and its directly attached customers.
If instead you're configuring an AS100 router (for example to filter
updates going out to EBGP neighbors) then you would use the following:
^([0-9]*)?$
This is because the 100 is not in the path internal to AS100.
Note that the '?' character in a regular expression means 0 or one of the
previous pattern. I've used the parens to denote the boundaries of the
pattern to apply the ? to. Also, note that you have to enter Ctrl-V
followed by ? to get the ? into the config, otherwise the ? is taken as
"show me the help."
David
At 11:05 AM 6/12/2004, ccienj wrote:
>Regular expression for AS 100 and as directly connected
>
> ^[0-9]*_100$
> but this will not catch routes originating from other AS say 200 connected
>to AS100.
>Any inputs?
This archive was generated by hypermail 2.1.4 : Sat Jul 03 2004 - 19:40:40 GMT-3