From: wangstone373 (wangstone373@hotmail.com)
Date: Fri Nov 21 2003 - 05:09:08 GMT-3
I think Kelly is right.
_2$ means route from AS 2, how about AS1 route?
_2_ is also wrong
----- Original Message -----
From: "Hoyle, Anthony (AL)" <ALHoyle@dow.com>
To: "'Kelly, Russell G'" <Russell_Kelly@eu1.bp.com>
Cc: <ccielab@groupstudy.com>
Sent: Friday, November 21, 2003 12:46 AM
Subject: RE: BGP Regular Expressions for as-path filtering
> Remember the regular expression for routes that originate will be _2$ (I only use that one if the AS is a couple of hops away.
> If it is an AS that is directly connected I tend to use ^2$.
>
>
> Anthony H
> EDS
> WAN Infrastructure Analyst
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Kelly, Russell G
> Sent: Thursday, November 20, 2003 11:07 AM
> To: ccielab@groupstudy.com
> Subject: FW: BGP Regular Expressions for as-path filtering
>
>
> Or possibly
>
> ip as-path access-list 1 permit _2_
>
> > -----Original Message-----
> > From: Kelly, Russell G
> > Sent: 20 November 2003 15:58
> > To: ccielab@groupstudy.com
> > Subject: BGP Regular Expressions for as-path filtering
> >
> > I have 3 AS's chained together as below:
> >
> > | AS 1 | -> | AS2 | -> | AS3 |
> >
> > AS1 and AS2 have all routers running BGP but AS redistributes BGP into
> > OSPF (and redistributes it's own OSPF routes into BGP). I want AS3
> > to only redistribute routes originating in AS1 and AS2 into OSPF (and
> > not redistribute these back into BGP!!!!!) and I am trying to come up
> > with a regular expression to achieve this. I am not too sure on the
> > as-path 1 ^2 1$ regular expression, or the redistribution tagging for
> > AS1. Will the 'better' reg expression be:
> >
> > ip as-path access-list 1 permit ^2.* (i.e. anything coming through
> > AS2???)
> >
> > The route maps and as-path statements currently are:
> >
> > ip as-path access-list 1 permit ^2 1$
> > ip as-path access-list 2 permit ^2$
> >
> > route-map BGP2OSPF permit 10
> > description Allow AS1 Routes
> > match as-path 1
> > set metric 100
> > set metric-type type-1
> > set tag 2 1
> > !
> > route-map BGP2OSPF permit 20
> > description Allow AS2 Routes
> > match as-path 2
> > set metric 100
> > set metric-type type-1
> > set tag 2
> > !
> >
> > route-map OSPF-TO-BGP deny 10
> > match tag 2
> > !
> > route-map OSPF-TO-BGP deny 20
> > match tag 2 1
> > !
> > route-map OSPF-TO-BGP permit 30
> >
> > Russ
>
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