Hi,
Reading the second bullet in the WB and also the SG for it ... I think there is something to talk about here.
So, the WB says :
• For the purposes of load balancing and redundancy AS 100 has multiple
connections to AS 54.
o In order to more evenly distribute the traffic load configure your
network so that all traffic from AS 100 destined for prefixes
originated in AS 54 transits the link to BB1.
o In addition to this configure your network so that all traffic from AS
100 destined for prefixes that are from thecustomers of AS 54 is
sent out towards BB3.
o In the case that the link to BB1 is down traffic for prefixes that have
been originated inside AS 54 should still be able to be rerouted to
BB3.
o All of this configuration should be done on R6.
I agree with the first part ... so on R6 configure an as-path access-list 1 permit _54$ to match routes ORIGINATED in AS54, combined with set local pref 200, alltogether in a route-map on R6 applied inbound. In the case link to BB1 fails, routes will still get advertised to AS100 by BB3 link.
Now the interesting part ... regarding this bullet :
o In addition to this configure your network so that all traffic from AS
100 destined for prefixes that are from the customers of AS 54 is
sent out towards BB3.
The SG is using the same as-path access-list to match this routes as well as routes originated in AS54.
Well, I would interpret the following "all traffic from AS 100 destined for prefixes that are from the customers of AS 54"
as being traffic FROM AS54 with at least one other AS present in the as-path.
In my config, I would use the following :
ip as-path access-list 2 permit ^54_[0-9]+
EDIT :
Or maybe even the following :
ip as-path access-list 3 permit ^54(_[0-9]+)+ ---->> To match routes coming from AS54 and having the AS-PATH length of at least 2.
What do you think of the above comments ?
Thanks,
Ciprian.