Subject: [siprec] Normative Statements in draft-ietf-siprec-protocol-13

From: Alan Johnston <[email-masked]>
Date: Fri, 25 Jul 2014 09:50:51 -0500

Here's a few comments on some normative statements in
draft-ietf-siprec-protocol-13.

"In order to communicate most effectively, the Session Recording Client
(SRC), the Session Recording Server (SRS), and any Recording aware User
Agents (UAs) SHOULD utilize the mechanisms provided by RTP in a
well-defined and predicable manner."

I question whether this statement should have normative language, since it
isn't testable at all.

"Using the FIR command to recover from errors is explicitly disallowed, and
instead the PLI message SHOULD be used."

The use of "disallowed" seems like a MUST NOT, but then PLI is a SHOULD
which is confusing.  I'd suggest using normative language instead of
disallowed.

There are a bunch of normative statements that are repeated twice in
different sections.  For example:

"If packet loss occurs from the UA to the SRC, the SRC SHOULD detect and
attempt to recover from the loss."

This statement appears in 8.2.2 and 8.2.3 for mixer and endpoint scenarios.
 There are similar things in 8.3.1 and 8.3.2.   Do we really want to repeat
this text?  If not, perhaps we could consolidate these two sections into
three:

- Section with normative statements that apply to both mixing and endpoint
- Section with normative for mixing only
- Section with normative for endpoint only

Or, if we do want to keep the existing structure, maybe the normative
statements could be prefixed with "For RTP mixing..." or "For RTP
endpoint..." so each normative statement is unique.

- Alan -