consistent policy != consistent announcements

Vadim Antonov avg at
Thu Mar 13 10:38:57 UTC 1997

Randy Bush wrote:

>A normal condition of peering between consenting adults is that the peers
>have consistent policy across all points where they peer.

[example of a quasi-consistent scenario skipped]

>Am I being unfair to my peers?  Would they be justified in making a stronger
>requirement than 'consistent' policy?  What requirement would be reasonable?

There are three quasi-answers:

1) it's ok with consent of parties involved (i.e. you may want to coordinate
fancy policies with peers)

2) generally speaking, BGP path length is too blunt an instrument.  More fine-grained
control is needed to allow peers to fine-tune balance of their interests.  I'm
sorry to be too naive, but i'm repeating that for years and nobody seems to agree
that BGP needs real metrics.  How come?

3) on a phylosophical level, all involved parties should have a way to control
destiny of routes, to a some extent.  Right now, it's either control local to
the destination (local preferences), or control by adjacent neighbour (MEDs).
There's no way to extend it further (save for as-replication kludgery) or to
combine local and remote metrics in any meaningful way.


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