From: Derek Fage (DerekF@xxxxxxxxxxx)
Date: Tue Aug 31 1999 - 13:11:43 GMT-3
Somebody sent me an email privately to remind me that AS paths are prepended
(talk about not seeing the woods for the trees !!!)
So to affect entries that originited from AS 3, (and travelled through other
AS's to get here), I need to use "_3$"
Ciao,
Derek...
> -----Original Message-----
> From: zyz [SMTP:zyz98@chinaweal.com]
> Sent: 31 August 1999 17:10
> To: Derek Fage
> Cc: ccielab@groupstudy.com
> Subject: re: BGP AS-PATH Questions
>
> i think you should use "3$" to stand for the route originated
> by as3.
> ---zyz
>
>
>
> >Well,
> >
> >I seem to be posting a lot of questions today, but I've got to travel
> down
> >to Brussels tommorrow in preparation for the lab on Thurs, and I'm
> running
> >through a bunch of final configs covering things I am a bit unsure of.
> >
> >This time it's BGP AS-PATH in route-maps
> >
> >I've got the following BGP entry (among others):
> >
> >*> 172.168.70.0/24 137.20.68.6 66 0 2 3 i
> >
> >What I wanted to do was to modify all BGP entries that came from the
> router
> >in AS3 to set the MED to 66.
> >
> >My initial attempt at this was as follows:
> >
> >router bgp 1
> > neighbor 137.20.68.6 remote-as 2
> > neighbor 137.20.68.6 route-map test-as-path in
> >!
> >ip as-path access-list 1 permit ^3_
> >ip as-path access-list 2 permit .*
> >!
> >route-map test-as-path permit 10
> > match as-path 1
> > set metric 66
> >!
> >route-map test-as-path permit 20
> > match as-path 2
> >
> >I thought that this would pick up all BGP entries originating from AS 3.
> >This did not work (presumably because of the 'i' in front of the 3 in the
> AS
> >path), so I changes the access-list 1 as follows:
> >
> >ip as-path access-list 1 permit _3_
> >
> >I'd like to check that this is in fact the best way to do it, as what I
> >think this is saying is to affect any routes that pass through AS 3. What
> >would I use to restrict this to routes originating from AS 3 ?
> >
> >Regards,
> >
> >Derek...
> >
> >ccielab@groupstudy.com
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