AS 690 aut-num progress (LONG!!!)

  > Curtis Villamizar <curtis at ans.net> writes:
  > 
  > There is one problem for which there is no way to express the
  > requirement in ripe-181.  There is no way to specify an as-in line
  > (which is required and has no means restrict to specific peers) and no
  > way to specify that certain destinations are not accepted at all at
  > some peers using interas-in or as-in lines.  This is need where we
  > peer with someone at two interconnects, accept one as primary and
  > don't accept the same set of routes from the other peering at all.

Curtis:

The philosophy here is that the as-in attribute describes the policy of the
ASes as a whole. So if you accept a route at any peer with a neighbour
you should list it in the as-in line.

When you have different policies at different peerings you describe them 
with interas-in attributes. If you do not accept a particular route 
from a neighbor on a specific peering you simply do not mention it in the 
corresponding interas-in attribute.

To quote from ripe-181:

"If we look at a simple example, taking just  in-bound  announcements
to simplify things. If we have the following global policy:


aut-num: AS1
as-in: from AS2 10 accept AS100 OR {10.0.0.0/8}

Suppose there are three peerings between AS1 and AS2, known  as  L1-
R1, L2-R2 and L3-R3 respectively. The actual policy of these connec-
tions is to accept AS100 equally on these three links and just route
10.0.0.0/8  on L3-R3. The simple way to mention this exception is to
just specify an interas policy for L3-R3:

interas-in: from AS2 L3 R3 (pref=100) accept {10.0.0.0/8}


The implicit rule that all routes not mentioned in interas  policies
are  accepted on all links with equal preference ensures the desired
result.

The same policy can be written explicitly as:

interas-in: from AS2 L1 R1 (pref=100) accept AS100
interas-in: from AS2 L2 R2 (pref=100) accept AS100
interas-in: from AS2 L3 R3 (pref=100) accept AS100 OR {10.0.0.0/8}"

Does this solve your problem?

Daniel



-------- Logged at  Mon Mar 20 16:39:25 MET 1995  ---------