Re: [ippm] Last Call: draft-ietf-ippm-more-twamp (More Features for the Two-Way Active Measurement Protocol - TWAMP) to Proposed Standard

["Romascanu, Dan (Dan)" <[e-mail]>]

Please find below the OPS-DIR review for draft-ietf-ippm-more-twamp
performed by Joel Jaeggli. 

Please consider these comments together with the other IETF LC comments.


Regards,

Dan


-----Original Message-----
From: [e-mail] [mailto:[e-mail]] On
Behalf Of Joel Jaeggli
Sent: Sunday, May 17, 2009 11:37 AM
To: [e-mail]
Subject: [OPS-DIR] Review of draft-ietf-ippm-more-twamp-01

review for opsdir of:

http://tools.ietf.org/html/draft-ietf-ippm-more-twamp-01

section 4 -

   "This section describes OPTIONAL extensions.  When the Server has
   identified the ability to support the mixed security mode, the
   Control-Client has selected the mixed security mode in its Set-Up-
   Response, and the Server responds with a zero Accept field in the
   Server-Start message, then these extensions are conditionally
   REQUIRED."

When I read the introduction to section 4 the following statement, it
sent me scrambling for the other conditions that would make the above
statement required.

It should be sufficient to say:

   When the Server has identified the ability to support the mixed 	
   security mode, the Control-Client has selected the mixed security
   mode in its Set-Up-Response, and the Server responds with a zero
   Accept field in the Server-Start message, these extensions are
   REQUIRED.

regarding 6.1 and 6.2 registry specification and management, 6.1 states:
 	"Thus, this registry can contain a total of 32 possible bit
	positions and corresponding values."

Certainly while there are 32 bits in the field, each has two states
(e.g. 64) and the sum of the possible positions is significantly greater
than 32 e.g. 2^32

6.2 states:

   For the TWAMP-Modes registry, we expect that new features will be
   assigned using monotonically increasing bit positions and in the
   range [0-31] and the corresponding values, unless there is a good
   reason to do otherwise.

at some future date values in the registry for some bit positions might
be encoded in some more complex fashion.