Mods to ripe181?

Jessica,

Andy and I already made changes to support this in peval and hence the
config files. What is missing is the documentation. I will get to it
after nanog. We can discuss the datails there if anyone is interested.

Jessica Yu (jyy at merit.edu) on February  3:
> This issue may come up before but never got addressed.  Now we have real problem
> 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 what
> AS to accept, we have to either describe to reject ASj or advertise ASj not
> advertise ASj when path is 130 ASj.
> 
> b) Usually, certain in this real AS's policy case, one does not know explicitly
> 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 case, we 
> 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 AS70in_the_path}
> 
> I suggest to use cisco's regular expression to represent the AS in the path
> 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


Cengiz

-- 
Cengiz Alaettinoglu       Information Sciences Institute
Voice: (310) 822-1511     University of Southern California




-------- Logged at  Fri Feb 3 23:38:50 MET 1995  ---------