Mods to ripe181?

Here are re-visiting an old discussion. I personally am not in
agreement with Enke on this one so this is not necessarily the whole
view of MCI.
		--Tony.

 Enke Chen <enke at mci.net> writes:
  * I agree with Jessica on the need of AS path in the as policy. 
  * The reality is that AS paths are widely used today in AS policies 
  * today.  Here is a very simple example, currently MCInet does 
  * not re-distribute to other NSPs the routes learned from a NSP.
  * This policy is very difficult (if not impossible) to describe 
  * without AS path. 
  * 
  * -- Enke    
  * 
  * 
  * > Date:    Fri, 03 Feb 1995 15:02:30 -0500
  * > From:    Jessica Yu <jyy at merit.edu>
  * > To:      rr-impl at ripe.net
  * > CC:      jyy at merit.edu
  * 
  * > This issue may come up before but never got addressed.  Now we have real 
  * probl
  * em
  * > to describe three major providers policies who I gather routing policies 
  * from.
  * > 
  * > I think we really need to seriously address this.  Below is an example to
  * > illustrate the problem and a suggestion to the solution.  
  * > 
  * > 
  * >                            ASh
  * >                            |
  * >                      ASi...ASj-------|
  * >                       \  | /         |
  * >                         130          |
  * >                          |          /
  * >                  ----------------- /
  * >                   |       |    |  /
  * >                  50      60    70 
  * >                 / \      / \    \
  * >               ASm...ASn ASx..ASy ASz
  * >                |
  * >               ASa
  * > 
  * > The Policy:
  * > 
  * > AS130 announce to AS50 everything but not any routes whose AS path starts
  *  with
  * > AS50,AS60 and AS70.
  * > 
  * > The difficulties here are 
  * > 
  * > a) AS130 wants to announce ASj to AS50 but not with
  * > the pass of 100 ASj.  Since RIPE181 only has homeAS concept in terms of w
  * hat
  * > AS to accept, we have to either describe to reject ASj or advertise ASj n
  * ot
  * > advertise ASj when path is 130 ASj.
  * > 
  * > b) Usually, certain in this real AS's policy case, one does not know expl
  * icitl
  * y
  * > what's behind AS130 i.e. ASi..Asj, ASh.  So it is near to impossible to 
  * > express such policy in ripe181 format.
  * > 
  * > The problem is that RIPE181 deals with home AS only.  To describe this ca
  * se, w
  * e 
  * > need introduce a concept of AS in the path.
  * > 
  * > Suggested mods:
  * > 
  * > Introduce AS in the path concept.  This will solve both problem a) and b)
  * .  To
  *  
  * > express the policy above:
  * > 
  * > as-out: to AS50 announce ANY AND NOT {AS50in_the_path, AS60in_the_path AS
  * 70in_
  * the_path}
  * > 
  * > I suggest to use cisco's regular expression to represent the AS in the pa
  * th
  * > concept.  It is widely used and therefore more people understands it.
  * > 
  * > as-out: to AS50 announce ANY AND NOT {^AS50_ ^AS60_ ^AS70_}
  * > 
  * > ^ means the right most of the ASpath.
  * > _ same as .* 
  * > 
  * > 
  * > 							--Jessica



-------- Logged at  Fri Feb 3 23:46:44 MET 1995  ---------