Richard,

I don¹t like that language ‹ it¹s too wishy-washy. If an ECS can ³use² a
Network Map, we need to spell out what that means.

So I support either of two alternatives.

(1) Say that an ECS MAY ³use² a Network Map, and spell out what that means.
E..g., if an ECS ³uses² a Network Map, then that ECS is equivalent to a
Filtered Cost Map resource on that Network Map, using the PIDs of the source
and destination endpoint addresses. This means the client can assume the ECS
will return the same cost for any endpoint in the source PID to any endpoint
in the destination PID (modulo cost updates).

If an ECS does not ³use² a Network Map, then the client can make no
assumptions about how the ECS costs relate to the costs for any PIDs or
endpoints.

(2) Say that ECS MUST NOT ³use² a Network or Cost Map. The ECS cost is the
cost from the source to destination endpoint; the client cannot draw any
conclusions about costs for PIDs or other endpoints.

BTW, I thought we¹d agreed on #2, until a colleague pointed out that
11.5.1.5 says an ECS can use a map.

- Wendy Roome

From:  "Y. Richard Yang" <[email protected]>
Date:  Tue, February 25, 2014 at 10:52
To:  Wendy Roome <[email protected]>
Cc:  IETF ALTO <[email protected]>
Subject:  Re: [alto] Ambiguity in ALTO draft 25

Hi Wendy,

Good discussion. I believe that the previous conclusion is that ECS does not
reveal any dependency. Hence, a simple change will be the last sentence:

"...However, to preserve flexibility, there is no need for the ECS resource
to declare the network map and/or cost map on which it depends."

How does this sound?

Richard



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