as-out metrics

  > Jessica Yu <jyy at merit.edu> writes:
  > Daniel,
  > 
  > Viewing the previous exchange, it looks like you agree that the routes
  > export metric is useful information and it needs to be somewhere.  

I agree and it needs to be in the AS object as it is under the control of
the announcing AS.

  > The
  > difference is where it should be put, in as-out or put it in a new
  > attributes. 

A new attribute.

  > It seems that metric out fits naturally in as-out for the following
  > reason:
  > 
  > as-in describes how an AS import routes including what routes to import
  > and what preference it accept them. 

correct.

  > as-out describes how an AS export routes including what routes to export
  > and what metric it announce them. 

preference!=metric

preference is a static preference, protocol independent.
It describes routing policy in a clearly defined way.

metric is protocol specific. It *may* affect routing policy 
in some way.

  > Both perference in as-in and metric in as-out are enforcable by the AS. 

Agreed. 

  > So it actually make as-out more symtric to as-in by adding export
  > metric.  And it also fits the definition of as-out. 

Symmetry for symmetry's sake is not necessarily a good idea.
Different things should go in different places.
Also what is so special about BGP metrics.
What metrics are in IDRP?

  > Create a new attribute of bgp_metric like you suggested has someside
  > that is:
  > 
  > ASs have to repeat what described in as-out in order just to put metric
  > with the different set of routes it advertised.  It is really redundant
  > to as-out. 

Agreed. 
How widely is it really used?
Is the metric maybe often defined per peer rather than per peerXAS?

Daniel



-------- Logged at  Fri Apr 29 20:35:35 MET DST 1994  ---------