2.7 -- BGP bestpath Selection.
The book uses as-path prepending, but I blocked the advertisement of the prefixes entirely to R3 on the other link from R2.
The task said this:
Configure AS 200 so that all traffic destined for prefixes in the 54:1 community come in the Serial link between R1 and R3.
My impression is "all' meant that it should never come in the other way -- even if you have say a link outage, but the book thought differently.
In previous labs, when they wanted you to use as-path prepending, they mentioned something about primary, preferred, or failover.