Subject: TSV Area review of draft-ietf-dime-qos-parameters

From: [email-masked] (Scott O. Bradner)
Date: Thu, 13 Nov 2008 16:43:44 -0500 (EST)

I've reviewed this document as part of the transport area directorate's ongoing
effort to review key IETF documents. These comments were written primarily for the
transport area directors, but are copied to the document's authors for their
information and to allow them to address any issues raised. The authors should
consider this review together with any other last-call comments they receive.

This ID describes some useful technology but I think it can be improved.

My main issue is that the ID does not do a good enough job of making clear what
the units of the parameters are or even what the meaning of some of the parameters
are.  Some of the information can be found by looking at the RFCs that are
referenced but it would be cleaner to just include the information in this
document.

I was initially confused by the fact that section 3 contained no information on
what the units of the parameters are but much of this is covered in section 4.
(if it were up to me I'd put the units in section 3 as well - e.g. in section 3.2
I'd say that "The <Path Latency> parameter (expressed in usec) refers to the
accumulated latency …" )

But not all of the units are explained in section 4 and some terms are left
undefined.

I'll only provide some examples here - I suggest that the authors step through the
document and be sure that the units as well as the terms are defined in every
case.

For example, in section 3.1.  The value "large" is not defined or explained, nor
is the term "policed unit".  The document does not say what the units for rate
(bytes per second?, packets per usec?) are or the units for bucket size (bytes?)
- an educated guess can be made but it would be better if no guessing were needed.

Another example, in section 3.2.  The units for packet loss rate are not given
(packets per second?  % of packets?)

Also, in section 4.5.  It would be nice to have a few words say what "99.9%-ile"
means and how to calculate it for those who might not know

nit: section 4.8 says "A description of the semantic of the parameter values can
be found in [RFC2212], [RFC2215]. "  Should this say " [RFC2212] and [RFC2215]"? 

nit: the first sentence under section 4.13.3 is not a sentence

nit: section 6.1 - 4th pp says "1 to 511: Standards Action" the pp following says
"range of 0-511"  - should these be consistent?

Scott

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