Subject: [AVT] Comments on draft-ietf-avt-rtcp-xr-mib-02

From: Magnus Westerlund <[email-masked]>
Date: Wed, 03 Aug 2005 15:35:59 +0200

Hi,

Mostly editorial comments:

1. Section 1: Could you please write the reference to STD 58 in another 
way. For example: STD 58 (RFC 2578, 2579, and 2580).

2. Page 5, The RFC editor note "-- RFC Ed: replace mmm with IANA 
assigned number and remove this note" does not have any MMM to be 
replaced. Is also the nnn reference before correct?

3. Page 8, rtcpXrSessionIDSessionIdentifier: I don't like the very fuzzy 
description of this attribute:
         "Unique identifier for this session.  Where a billing record
          correlation identifier is not available for a particular call,
          another identifier such as SSRC can be used."
How is anybody supposed to know what to fill in this field unless it is 
actually specified?

4. Page 9: rtcpXrSessionIDSourceIPType:
""Source IP address type for this session."
I have a problem that saying that a SESSION has a single Source address. 
This comment applies to the following source and destination attributes. 
I think one needs to talk about session participants or so.

5. Page 11, rtcpXrSessionIDMeasurePtID:
What type of ID is this. Currently it is totally unspecified in which 
way one describes the measuring point.

6. Page 13, rtcpXrBaseParamVocoderType:
First of all the VocoderType is not something I think is totally well 
describing. An audio encoder is not necessarily an Vocoder. I would 
propose changing VocoderType to MediaEncoding.

Secondly, it need to be specified per PT in use.

Third, it should use a specified name space, like media type including 
parameters.

7. Page 13, rtcpXrBaseParamVocoderRate:
First, name, it think MediaEncodingRate would be more correctly describing.

Secondly, The description should clarify that it is "bit-rate" that it 
described.

8. Page 14, rtcpXrBaseFramesPerPAcket:
         "Number of vocoder frames for this RTP session contained
          in a single IP packet. The duration of speech per IP
          packet is the product of Frame Duration and Frames Per
          Packet."

This parameter has two problems as currently specified. First of all it 
can't be applied on a session level, it is a SSRC specific description.

Secondly, it is dependent on the point of time as it may be changed at 
any point.

9. Page 16, rtcpXrBasePAramAvgOWDelay:
         "Average (symmetric) one way RTCP delay on call. A value of
          zero may indicate that this value has not yet been determined."

The "may" in the second sentence is problematic. It need to be 
normatively defined how the values shall be interpret, including if 0 
shall be interpreted.

10. Page 24 history parameters, All that are measurements, do lack in 
there description a normative reference to how they are calculated.

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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