Subject: [alto] WGLC of draft-ietf-alto-reqs-07

From: Richard Alimi <[email-masked]>
Date: Fri, 25 Feb 2011 08:40:29 -0800

Hi All,
The following is a review of draft-ietf-alto-reqs-07.  Overall, very
good draft.  Now some more detailed comments (note that some are
nits):

Terminology:
- Host Group Descriptor:
  - can also be used to group resource consumers, though text seems to
indicate that it describes a single one
  - Perhaps a sentence saying why it is introduced (before discussing
the tradeoffs)

Architectural Framework:
- " find out where to send ALTO requests." -> "determine one or more
ALTO servers to be used"?

Requirements:

Should ARv07-5 be moved somewhere else, e.g., into text?  It seems a
bit recursive in the current location :)

ARv07-11: Is this intended to cover the concept of a PID, or extend to
other types of addresses?
- If for a PID, I understand, but it it is somewhat confusing.  It
appears to limit us to supporting addresses that are IPv4/v6 or could
be mapped into that space.  Maybe it might be helpful to introduce the
fact that could be used to provide a grouping for Host Group
Descriptors.
- If for other types of addresses, why is it needed?

ARv07-12: similar discussion w.r.t. ARv07-11

ARv07-13: Clarify what "the other party" refers to?

ARv07-16:
- It may be better to avoid using "higher" or "lower" since it could
be confused with the actual numerical values. For example, a lower
cost could be more-preferred. Maybe use "more-preferred" or
"less-preferred"?
- "unless information from non-ALTO sources suggests a different
choice, such as transmission attempts suggesting that the path is
currently congested" - Maybe it would be better to state outside of
the body of the requirements that ALTO guidance is just an information
source. There does not need to be a binding agreement to use it.
The paragraph beginning with "One design assumption for ALTO is that
it is acceptable that the host characteristics attributes..." - This
seems a bit out of place intermingled in the requirements?  Maybe
restate it as a requirement (something along the lines of "the ALTO
Protocol MUST support providing guidance at intervals ..."), or as
additional detail within ARv07-18.

ARv07-20: I'm a bit skeptical of whether the ALTO Server would need to
know the relative weighting for the different criteria available.
Could this be done on the client-side?  Maybe split this into two
requirements (the first being a MUST requirement indicating that the
ALTO Client should specify the rating criteria, and a second being a
MAY/SHOULD requirement indicating that the ALTO Client could specify
the relative importance)?

ARv07-31: In the last bullet point, it seems that the ".. to any ALTO
server" needs some qualification. Does that really mean all ALTO
servers globally? Or ALTO Servers within the same administrative
domain?

ARv07-35: Why do we need to state requirements on applications? Should
this instead be stated as an assumption before presenting the
requirements?

Section 5.2.1:
- " There are a couple of sub-cases here" - There are actually 3 :)

Section 5.2.2:
- Regarding the the target-aware query mode, it may be worth noting
that the effectiveness is limited in certain modes. In the third-party
mode, this might be doable. If the queries are being sent from the
ALTO Client itself, the source IP address may be revealed directly (as
the Source IP address on the received packets) if there are no NATs
involved.

In Appendix A, can you please change my email address to "[email-masked]"?

Thanks!
Rich