Re: requirements draft revision

[Joe Abley <jabley-ietf@automagic.org>]

On Tue, Jun 26, 2001 at 09:04:15PM -0700, Tony Hain wrote:
> In multi6-multihoming-requirements requirement - 3.1.3 Performance -  is
> simply bogus. The example given is managing traffic flows to avoid a
> specific remote congestion point. As it is not possible for any organization
> to reliably affect the routing policies of another organization (even the
> first hop), this is basically an unrealistic expectation.

In the current v4 architecture, it is overwhelmingly usual for an
operator to assign a higher local preference to prefixes received
from a customer than from a peer.

If I am a customer of T1, I can be very confident that the path from
T1 to me will follow the prefixes I advertise rather than a route
through a peer, for advertisements of the same mask length.

This absolutely happens today, and people absolutely multi-home today
in order to accomplish this.

> Taken to the
> limit, the requirement presented means every site has ultimate real-time
> control of routing policy for every service provider as well as all the
> remote sites they have active flows with. Even if each service provider
> wanted to cede control, the mismatch of policy constrains between the
> collections of end sites will assure this requirement can't be met because
> it has to be true for each of them.
> 
> Since I assume you have some specific implementation in mind it might help
> if there were an example provided. Without that this requirement simply
> needs to be removed.

This requirement comes from the observed fact that this happens today,
and works very reliably.

Suppose for a second a large, popular on-line auction company obtained
transit through one particular provider, and that provider had a problem
of peering congestion to some other large promising regional ISP that
was taking months to sort out. An immediate solution for the auction
company was to purchase transit from the promising regional ISP, which
eliminates the congestion point that had been causing them such pain.

[note that the congestion condition hypothetically alluded to above
would surely no longer be an issue, if we consider the fabricated
example to be real in some way]


Joe