RE: Reg Experts!

> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On
> Behalf Of Jack Router
> Sent: Wednesday, June 09, 2010 2:28 PM
> To: ccielab_at_groupstudy.com
> Subject: RE: Reg Experts!
>
> 1.
> ^200_300$ - as path is "200 300"
> _200_300$ - as path must end with "200 300", for example "111 222 333 200
> 300"
>
> 2.
> ^([0-9]+)?$ - Does it make sense ? Just the part ([0-9]+) tells me that AS must
> be 10 digit long. There is no such AS.

^([0-9]+)?$ Matches just a single AS number.
^([0-9]+)(_1\)*$ - remove the trailing ) and it will also match only AS paths which contain a single AS.
_100+ matches any AS path that which contains an ASN that starts with 100, i.e. 100 10002 1001.

> ^([0-9]+)(_1\)*$ - Same as above and the expression looks invalid if tested
> on a public router:
>
> route-views.optus.net.au>sh ip bgp regexp ^([0-9]+)(_1\)*$
>
> % unmatched ()
> % Invalid regular expression
>
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On
> Behalf Of Poplawski, James
> Sent: 9-Jun-10 13:19
> 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
>
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Received on Wed Jun 09 2010 - 18:56:48 ART