Re: [ippm] Fw: New Version Notification for draft-elkins-ippm-pdm-metrics-00.txt

["MORTON, ALFRED C (AL)" <[e-mail]>]

Hi Nalini and all,

Here are a few comments on your IPPM draft. I've looked at some
of the background stuff previously, but some of those details may be foggy now.
Hopefully the questions below are clar.

regards,
Al

Early in the Intro, the various time/number fields are referred to as "base metrics" themselves.
I know you'll want to clarify that (they are just fields).

In section 1.2: in addition to time and seq number for current packet:

                 PSNLR : Packet Sequence Number Last Received
                 TSLR  : Timestamp Last Received

the device supplying the header appears to need to maintain flow state to add
these "last packet" fields. A very strong justification is probably needed. 
Later, I see that the Server host essentially has to store the fields across 
request-response pairs. Lower and higher layers need to work together,
somehow.

In Section 3.1 and 3.2, it's not clear which PDM time-stamps support the (round-trip delay
and server delay) metrics. When you look at  RFC2681, it should be fairly clear where 
the time stamps are applied, and that needs to carry though here (though I see it later
in the example).

Looking at the example in section 4, there can be a significant delay between when
the application layer transfers packets to TCP's send buffer and when the packets are
actually sent "on the wire" (as we say in IPPM), which happens after the IP header is
applied (or most of the header, in some cases). How would accuracy be maintained
across all the different layers? 

Maybe another way to phrase the question is this:
How does the process that adds the PDM header (with last Seq number 25) know 
which packet to add it to? 

I note that there is IPR declared on this draft, and licensing is not clear.

________________________________________
From: [e-mail] [[e-mail]] On Behalf Of Nalini Elkins [[e-mail]]
Sent: Friday, October 04, 2013 9:10 AM
To: WG ([e-mail]); 6man WG; [e-mail]
Cc: Sigfrido Perdomo; [e-mail]; Bill Jouris; Ackermann Michael
Subject: [ippm] Fw: New Version Notification for        draft-elkins-ippm-pdm-metrics-00.txt

We have submitted a number of drafts.  Some are new and some are updates to our existing PDM proposal.  We would appreciate any comments, questions, and corrections from the lists.


The new ones are:

1.  In IPPM:

http://www.ietf.org/internet-drafts/draft-elkins-ippm-pdm-metrics-00.txt

This describes the base and derived metrics which can be obtained from the IPv6 PDM DO Extension Header.


2.  In TicToc:

http://www.ietf.org/internet-drafts/draft-ackermann-tictoc-pdm-ntp-usage-00.txt

This describes how NTP may be implemented to support PDM.


The updates are as follows

1.  In 6man:

http://www.ietf.org/internet-drafts/draft-elkins-ippm-pdm-metrics-00.txt

This is the layout of the PDM DO header.


2.  In v6ops:

http://www.ietf.org/internet-drafts/draft-elkins-v6ops-ipv6-packet-sequence-needed-01.txt

http://www.ietf.org/internet-drafts/draft-elkins-v6ops-ipv6-pdm-recommended-usage-01.txt

http://www.ietf.org/internet-drafts/draft-elkins-v6ops-ipv6-end-to-end-rt-needed-01.txt

These are background for the proposal.


Thanks,

Nalini Elkins
Inside Products, Inc.
[phone]
www.insidethestack.com

----- Forwarded Message -----
From: "[e-mail]" <[e-mail]>
To: Nalini Elkins <[e-mail]>; William Jouris <[e-mail]>
Sent: Thursday, October 3, 2013 8:04 PM
Subject: New Version Notification for draft-elkins-ippm-pdm-metrics-00.txt


A new version of I-D, draft-elkins-ippm-pdm-metrics-00.txt
has been successfully submitted by Nalini Elkins and posted to the
IETF repository.

Filename:    draft-elkins-ippm-pdm-metrics
Revision:    00
Title:        IPPM Considerations for the IPv6 PDM Extension Header
Creation date:    2013-10-03
Group:        Individual Submission
Number of pages: 14
URL:            http://www.ietf.org/internet-drafts/draft-elkins-ippm-pdm-metrics-00.txt
Status:          http://datatracker.ietf.org/doc/draft-elkins-ippm-pdm-metrics
Htmlized:        http://tools.ietf.org/html/draft-elkins-ippm-pdm-metrics-00


Abstract:
  To diagnose performance and connectivity problems, metrics on real
  (non-synthetic) transmission are critical for timely end-to-end
  problem resolution. Such diagnostics may be real-time or after the
  fact, but must not impact an operational production network. These
  metrics are defined in the IPv6 Performance and Diagnostic Metrics
  Destination Option (PDM). The base metrics are: packet sequence
  number and packet timestamp. Other metrics may be derived from these
  for use in diagnostics.  This document specifies such metrics, their
  calculation, and usage.





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