From: ying c (bf5tgh1@xxxxxxxxx)
Date: Sat Aug 24 2002 - 14:45:49 GMT-3
Brian,
Thanks to point my mistake out. I wish I can see and
think as clear as you guys.
Thanks,
Chang
--- Brian McGahan <brian@cyscoexpert.com> wrote:
> Chang,
>
> What Brian was referring to was in the case of an
> AS set. It is
> a possibility that an AS along the way who is
> learning prefixes that
> were originated in AS 10 is aggregating them, and
> including the AS set.
> Since I'm not checking for any instances of 10 in an
> AS set, Brian is
> technically correct.
>
> However, since AS set is an ordered set, there is
> no way to
> check whether or not the prefixes were actually
> originated in AS 10, or
> merely transited through AS 10 before aggregation.
>
> On a side note, Chang, you mentioned "I know we can
> replace
> (.*_) with (.*) and still get the same result."
> Actually this is not
> the case. If you remove the _, you would match the
> case of: 1000 100
> x10, where x is any number. The _ ensures that the
> AS path ends with
> exactly 10.
>
> HTH
>
> Brian McGahan, CCIE #8593
> Director of Design and Implementation
> brian@cyscoexpert.com
>
> CyscoExpert Corporation
> Internetwork Consulting & Training
> http://www.cyscoexpert.com
> Voice: 847.674.3392
> Fax: 847.674.2625
>
>
> -----Original Message-----
> From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> ying c
> Sent: Saturday, August 24, 2002 10:56 AM
> To: Brian Dennis; 'Brian McGahan';
> msnyder@revolutioncomputer.com;
> 'Bauer, Rick'
> Cc: ccielab@groupstudy.com
> Subject: RE: regexp fun (multiple solutions)
>
> Brian,
>
> I even could not come up a single case. Take the
> first
> solution and break them down:
>
> ^1000_(.*_)?100_(.*_)?10$
>
> ? = 0 0 => ^1000_100_10$
> ? = 0 1 => ^1000_100_(.*_)10$
> ? = 1 0 => ^1000_(.*_)100_10$
> ? = 1 1 => ^1000_(.*_)100_(.*_)10$
>
> I know we can replace (.*_) with (.*) and still get
> the same result, but I think they pretty much cover
> all the ground, so what exactly is missing?
>
> Thanks,
> Chang
>
> --- Brian Dennis <brian@5g.net> wrote:
> > Brian,
> > You said "all routes originated in AS 10, passed
> > through AS 100, and
> > learned from AS 1000", right? There are cases
> where
> > your regular
> > expressions won't meet the criteria ;-)
> >
> > Brian Dennis, CCIE #2210 (R&S/ISP Dial)
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com
> > [mailto:nobody@groupstudy.com] On Behalf Of
> > Brian McGahan
> > Sent: Thursday, August 22, 2002 9:06 PM
> > To: msnyder@revolutioncomputer.com; 'Bauer, Rick'
> > Cc: ccielab@groupstudy.com
> > Subject: RE: regexp fun (multiple solutions)
> >
> > Try these:
> >
> > ^1000_(.*_)?100_(.*_)?10$
> >
> > ^1000_(|.*_)100_(|.*_)10$
> >
> > ^1000_([0-9]+_)*100_([0-9]+_)*10$
> >
> > Brian McGahan, CCIE #8593
> > Director of Design and Implementation
> > brian@cyscoexpert.com
> >
> > CyscoExpert Corporation
> > Internetwork Consulting & Training
> > http://www.cyscoexpert.com
> > Voice: 847.674.3392
> > Fax: 847.674.2625
> >
>
>
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