Junos OS

Hello Community

Can some one please help me defining the Regex for following conditions.

1- All routes sourced from as AS

2-All routes that transited an AS.

To me the Rgex for Condition number 1 wil be

".*ASnumber" As the routes sourced from a prticular AS will have that AS as number attached at the right most of Aspath.

2- ".*ASnumber.*" as the routes that transited a particular AS will be somewhere in between the first and last AS.

What do you guys think is it alright.

Thanks & Regards

Malik

That looks right - depending on how you implement exactly.

An AS path regex of '.* 65500' will match all AS paths that end in 65500.  (e.g. '65500', '65499 65500')

An AS path regex of '.* 65500 .*' will match all AS paths that contain/transit 65500.  Note: this will also include AS paths originating from AS 65500.  (e.g. '65500' '65499 65500', '65499 65500 65501')

You just have to remember when creating your policy statements that if you perform a non-terminating action on regex #1, originating AS paths would also match regex #2.

You'll need ".* 65000$" for originating.

Hello Hanks

Can you please elaborate a bit.Thank you

Regards

Malik

The '.* 65500$' expression is a little more explicit - the '$' signifies the end of the AS path.  However, I believe the use of this character is optional, as it is added implicitly in Junos.

http://en.wikipedia.org/wiki/Regular_expression