Re: [xrblock] WGLC fordraft-ietf-xrblock-rtcp-xr-discardandxrblock-rtcp-xr-discard-rle-metrics

[Qin Wu <[e-mail]>]

----- Original Message ----- 
From: "Varun Singh" <[e-mail]>
To: "Claire Bi(jiayu)" <[e-mail]>
Cc: "xrblock" <[e-mail]>
Sent: Saturday, June 16, 2012 7:43 AM
Subject: Re: [xrblock] WGLC fordraft-ietf-xrblock-rtcp-xr-discardandxrblock-rtcp-xr-discard-rle-metrics


> Hi,
> 
> Quickly responding to the comments here.
> 
> On Thu, Jun 14, 2012 at 8:12 PM, Claire Bi(jiayu) <[e-mail]> wrote:
>> I have three minor comments to draft-ietf-xrblock-rtcp-xr-discard:
>> a. Section 1.1, last paragraph:
>> Remove "(work in progress)"
>> b Section 3.2, Definitionof "Discard Type".
>> Change the order of four Discard type allocated as follows:
>> NEW TEXT:
>> "
>>          00: packets are discarded due to too early arrival.
>>          01: packets are discarded due to too late arrival.
>>          10: packets are discarded due to both early arrival and late
>>          arrival.
>>           11: packets are discarded due to other reasons than late
>>          arrival, early arrival, or both (e.g., duplicate, redundant
>>          packets).
>> "
> 
> 
> The burst gap discard draft requires reporting total discarded packets
> in the discard packet and it cites that the discard draft carries this
> information. So this needs to be fixed or the dependency on the
> discard draft should be removed.
> 
[Qin]: That's a good question. However in the version -03 of burst gap draft doesn't
depend on discard draft since "summary statitistics metrics" (e.g., burst discard rate, gap discard rate)
has already been moved to draft-zorn-xrblock-rtcp-xr-al-stat, please see section 3.3 for details.
Now draft-zorn-xrblock-rtcp-xr-al-stat relies
on both burst gap draft and discard draft to calculate "Gap Discard Rate". 
According to section 2.1 of Discard draft and section 2.1 of Burst Gap Discard draft,

Discarded shall be regarded as A packet that arrives within
this time window but is too early or late to be played out.

Therefore I propose the following change to Discard draft:
OLD TEXT:
"
   Discard Type (DT): 2bits

      This field is used to identify the discard type used in this
      report block.  The discard type is defined as follows:

         00: packets are discarded due to other reasons than late
         arrival, early arrival, or both (e.g., duplicate, redundant
         packets)

         01: packets are discarded due to too early arrival.

         10: packets are discarded due to too late arrival.

         11: packets are discarded due to both early arrival and late
         arrival.
"
NEW TEXT:
"
   Discard Type (DT): 2bits

      This field is used to identify the discard type used in this
      report block.  The discard type is defined as follows:

         00: packets are discarded due to too early to be played out.

         01: packets are discarded due to too late to be played out.

         10: packets are discarded due to both early and late to be played out.

         11: packets are discarded due to other reasons than late
         arrival at playout buffer, early arrival at playout buffer, or both (e.g., duplicate, redundant
         packets)
"


Also I propose the following
text in the draft-zorn-xrblock-rtcp-xr-al-stat to get in line with change to Discard draft and discard definition of section 2.1 of Discard draft.

"
   Gap Discard Rate: 16 bits

      The fraction of packets discarded during gaps since the beginning
      of reception expressed as a fixed point number with the binary
      point at the left edge of the field.  This value is calculated by
      dividing the difference between number of packets discarded and
      Packets Discarded in Bursts by the difference between Packets


      Expected and Total Packets expected in Bursts as follows:

      (number of packets discarded - Packets Discarded in Bursts) /
      (Packets Expected - Total Packets expected in Bursts)

      where "number of packets discarded" is obtained from the RTCP XR
      Discard Block [DISCARD] and Packets Expected is calculated as the
      difference between "extended last sequence number" and "extended
      first sequence number" (Interval or Cumulative) provided in the
      Measurement Information block [MEASIDENT]."
NEW TEXT:
"
   Gap Discard Rate: 16 bits

      The fraction of packets discarded during gaps since the beginning
      of reception expressed as a fixed point number with the binary
      point at the left edge of the field.  This value is calculated by
      dividing the difference between number of packets discarded and
      Packets Discarded in Bursts by the difference between Packets


      Expected and Total Packets expected in Bursts as follows:

      (number of packets discarded - Packets Discarded in Bursts) /
      (Packets Expected - Total Packets expected in Bursts)

      where "number of packets discarded" is obtained from the RTCP XR
      Discard Block [DISCARD] with "Discard Type" field set to 2      (i.e.,packets are discarded due to both early to be played out and late to be played out.)       and Packets Expected is calculated as the
      difference between "extended last sequence number" and "extended
      first sequence number" (Interval or Cumulative) provided in the
      Measurement Information block [MEASIDENT]."