Implementation of RIPE-181++ (fwd)

I have CC'ed the list again...

Laurent Joncheray <lpj at merit.edu> writes
 * > The algorithm is easy (for any of the above policy expressions). For
 * > every net/route found in the database, check whether the match the
 * > boolean policy expression. So, in the as-in or nap3 interas-in case
 * > they would have an origin of AS100 or they would have to be route
 * > 10.0.0.0/8. This is no different than any policy expression. I still
 * > do not see the difficulty.....
 * 
 * There is no diffilculty. I just want to be sure of the correct syntax.
 * Could you detail the algorithm? What to do if there are as-in and interas-in
 * ,
 * only as-in, only interas-in (error), nothing? which one to choose first?
 * 		Laurent

OK Here goes. ripe-81++ says pp 27-28 in ascii version:

"Descriptions of interas policies do  not  replace  the  global  pol-
icy  described   in  as-in, as-out and other policy attributes which
should be specified  too.   If  the  global  policy  mentions   more
routes   than  the  local  policy  then  local preferences for these
routes are assumed to be equal for all links.


Any route specified in interas-in/out and not specified in as-in/out
is  assumed not accepted/announced between the ASes concerned. Diag-
nostic tools should flag this inconsistency as an error.  It  should
be  noted  that  if an interas-in or interas-out policy is specified
then it is mandatory to specify the corresponding global  policy  in
the  as-in  or as-out line. Please note there is no relevance in the
cost associated with as-in and the preferences used in interas-in."


I think this can be done by calculating the intersection between the
various expressions.

My solution can (with the above in mind) even be written as:

aut-num:    AS1
as-in:      AS2 100 AS100 OR {10.0.0.0/8}
interas-in: AS2 as1nap3 as2nap3 {10.0.0.0/8}

This means that you only have to list the exceptions in interas-in.
The above is of course only true if they all have the same metric. A
different metric means an exception.

 * PS: You're getting close to the beer....

I want that beer.....

-Marten



-------- Logged at  Tue Sep 20 17:08:33 MET DST 1994  ---------