[j-nsp] BGP import policy to accept prefixes from advertising AS only.

[Hannes Gredler]

On Thu, Oct 14, 2004 at 12:02:19PM +0200, Robert Kiessling wrote:
| Hannes Gredler <hannes at juniper.net> writes:
| 
| > explanation: the wildcard . plus the + operator means:
| >   any single element in the AS_PATH or
| >   repetitions of that single element;

apologies - i was wrong;

the + operator equals {1,} - and it is applied to the
wildcard and not the element;

i.e. .+ creates permutations like

.
..
...
....
.....
etc.

and not (example peer AS 1)

1
1 1
1 1 1

seems there is no easy/generic policy for catching
prepended ASes of a given peer;

corrected config:

policy-options {
    policy-statement peer_routes_only {
        term 1 {
            from {
                protocol bgp;
                as-path any_AS;
            }
            then accept;
        }
        term last {
            then reject;
        }
    }
    as-path any_AS ".";
}

--

/hannes