From: Ivan (ivan@iip.net)
Date: Tue Aug 22 2006 - 10:00:54 ART
Some more precise. I think that "CUSTOMERS of AS 54" is ^54_[0-9]+$
> Hi, Buddys,
>
> I am quite confused when doing IEWB Lab 7 Q 5.3 Bestpath Selection.
>
> It reads
> " ... configure your network so that all traffic from AS100 destined for
> prefixes ORIGINATED in AS 54 transits the link to BB1."
> " ... configure your network so that all traffic from AS100 destined for
> prefixes that are FROM CUSTOMERS of AS 54 is sent out towards BB3"
>
> >From my understanding, "prefixes originated in AS54" should be directly
> > from
>
> AS 54 (by network statment or redistribution), thus the AS_PATH should be a
> single "54" when entering AS100. Those willl some other things ahead of 54
> should be orginiated from other AS, i.e., "prefixes from customers of AS
> 54". Thus I designed the answer as:
> !
> router bgp 100
> bgp default local 100
> nei 54.1.7.254 route-m BB1 in
> nei 204.12.1.254 route-m BB3 in
> !
> ip as-pa access-l 1 per ^54$
> !
> route-m BB1 per 1
> m as- 1
> s local- 200
> !
> route-m BB1 per 10
> !
> route-m BB3 per 10
> m as-path 1
> s local- 50
> !
> route-map BB3 per 20
> !
>
> But when I checked it up with the answer I found the answer is roughly the
> same but it's AS_PATH access list uses _54$ instead of ^54$. From my
> understanding that _54$ matches anything ends with 54. And in this answer
> it is the same as match anything as this is applying on the EBGP neighbour
> of AS 54. Thus I can not agree with this answer. Anyone got comments on
> it?
>
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-- Ivan
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