Implementation of RIPE-181++

Marten,

It is interesting to see your interpretation. 

Marten Terpstra (Marten.Terpstra at ripe.net) on September 20:
> "If the global policy mentions more routes than the *combined local
> policies* then local preferences for these routes are assumed to be
> equal for all links."

With this I am no longer confused. I see that both of your
solutions are correct with this interpretation: 
  Marten Terpstra (Marten.Terpstra at ripe.net) on September 20:
  > aut-num:    AS1
  > as-in:      AS2 100 AS100 OR {10.0.0.0/8}
  > interas-in: AS2 as1nap1 as2nap1 AS100
  > interas-in: AS2 as1nap2 as2nap2 AS100
  > interas-in: AS2 as1nap3 as2nap3 AS100 OR {10.0.0.0/8}
  Marten Terpstra (Marten.Terpstra at ripe.net) on September 20:
  > aut-num:    AS1
  > as-in:      AS2 100 AS100 OR {10.0.0.0/8}
  > interas-in: AS2 as1nap3 as2nap3 {10.0.0.0/8}

However, this interpretation is not natural and is not easy to
understand for a more general reader. Especially your second solution:
  Marten Terpstra (Marten.Terpstra at ripe.net) on September 20:
  > aut-num:    AS1
  > as-in:      AS2 100 AS100 OR {10.0.0.0/8}
  > interas-in: AS2 as1nap3 as2nap3 {10.0.0.0/8}

Natural policy for nap1 and nap2 is the one in as-in:
	accept AS100 OR {10.0.0.0/8}.
But in fact, the policy for nap1 and nap2 is
	accept AS100
since {10.0.0.0/8} is mentioned in a local policy. A
non-careful/ignorant administrator will think the first way.

If the administrators of AS1 were even less careful and typed:
  aut-num:    AS1
  as-in:      AS2 100 AS100 OR {10.0.0.0/8}
  interas-in: AS2 as1nap3 as2nap3 AS100 OR {10.0.0.0/8}
the policy for nap1 and nap2 is
	accept NOT ANY
since both AS100 {10.0.0.0/8} are mentioned in a local policy.

This is even scarier, if {10.0.0.0/8} was in AS100 and AS1 did not
accept {10.0.0.0/8} on nap3:
  aut-num:    AS1
  as-in:      AS2 100 AS100
  interas-in: AS2 as1nap3 as2nap3 AS100 AND NOT {10.0.0.0/8}
the policy for nap1 and nap2 is
	accept {10.0.0.0/8}





To sum-up with the new text (and with better explained "combined local
policies"), I think there is no more ambiguity. However, it is a
difficult and unnatural solution.




How about the following solution:
as-in policies are used in all links for which no interas-in policy is
explicitly specified (like a default interas-in policy).
If for a link an interas-in policy is specified, it is used and
as-in policies are ignored.

with this the correct solution to Laurant's problem is:
aut-num:    AS1
as-in:      AS2 100 AS100
interas-in: AS2 as1nap3 as2nap3 AS100 OR {10.0.0.0/8}

If a tool needs to know the global combined policy of an AS1, it takes
the union of all as-in and interas-in policies.
	AS100 OR (AS100 OR {10.0.0.0/8}) = AS100 OR {10.0.0.0/8}.

To me this is more natural. 

Cengiz

P.S. Do we get to split the beer?
-- 
Cengiz Alaettinoglu       Information Sciences Institute
cengiz at isi.edu            University of Southern California




-------- Logged at  Thu Sep 22 16:21:31 MET DST 1994  ---------