North American Network Operators Group
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Re: some musings on PI v. PA

  • From: Seth Mattinen
  • Date: Thu Jul 12 20:27:58 2007

David Meyer wrote: 
      OTOH, if I announce PI space, "switching to the new path"
      is controlled by the announcement/withdrawal of the PI
      prefix, and can happen much closer to the source. So in
      this sense aggregation breaks a certain kind of "path
      selection". I think we all realize that there is no free
      lunch, and that this is a property (such as it is) of the
      fact that aggregation throws away information in the
      interest of computability (a standard technique).

      So folks are using PI for reasons other than the
      well-known standard laundry list. In particular,
      advertising PI space can cause the "switch" to an
      alternate path during an outage to happen much closer to
      the source and some providers find this to be a desirable
      property.

      I am interested in hearing about anyone who is relying on
      this property of PI, or any other comments on what I've
      said above.


I always thought that *was* one of the major reasons to use PI space -
no aggregation of your space into another announcement. Not having to
renumber is ancillary to me.

~Seth