On 10/31/2011 08:49 AM, Bill Roome wrote:
I don't have complaints, but I do have an observation: A client
cannot distinguish between "pids are invalid" and "pids are valid but
this server doesn't have reliable cost data for that pair."
Does that bother anyone?
The problem, at least as I understand it, is not predicated on a PID
being valid or invalid.
The validity (or lack thereof) of the PIDs is a function on whether
they appear in the network map and cost map. Presumably, if they
appear there, the PIDs are valid.
However, the greater question is this: does the ALTO provider know
authoritatively the cost between all PIDs? That is the issue
under discussion.
Clearly, the ALTO provider cannot know the costs between all PIDs.
Again, consider our sample topology we used for the bakeoff [1]. In
that topology, the ALTO provider had authoritative costs for
mypid{1,2,3} -> mypid{1,2,3} +
peeringpid{1,2} +
transitpid{1,2} +
defaultpid
However, asking the ALTO server to provide a cost between defaultpid
(Internet) and transitpid1 is useless, since at best, the server will
be indulging in a guess (and at worst, it'd be lying).
[1] http://www.ietf.org/mail-archive/web/alto/current/msg01147.html
Thanks,
- vijay
--
Vijay K. Gurbani, Bell Laboratories, Alcatel-Lucent
1960 Lucent Lane, Rm. 9C-533, Naperville, Illinois 60566 (USA)
Email: vkg@{bell-labs.com,acm.org} / [email protected]
Web: http://ect.bell-labs.com/who/vkg/
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