Subject: [ntpwg] Updated NTPv4 Protocol Specification

From: Brian Haberman <[email-masked]>
Date: Tue, 20 Nov 2007 09:32:12 -0500

NTP WG,
      The latest NTPv4 protocol specification has been published.  This
revision should address all Last Call issues raised except for
additional text on the timing reference point.  I did not see any
consensus on the mailing list on the text proposed by Rich Osman using
the LI as the reference point.  Please review this version for all other
changes.

      If you have comments on the reference point for the start time,
please post that to the mailing list.

Regards,
Brian

-------- Original Message --------
Subject: I-D ACTION:draft-ietf-ntp-ntpv4-proto-08.txt
Date: Mon, 19 Nov 2007 12:15:01 -0500
From: [email-masked]
Reply-To: [email-masked]
To: [email-masked]
CC: [email-masked]

A New Internet-Draft is available from the on-line Internet-Drafts
directories.
This draft is a work item of the Network Time Protocol Working Group of
the IETF.

	Title		: Network Time Protocol Version 4 Protocol And Algorithms
Specification
	Author(s)	: J. Burbank, et al.
	Filename	: draft-ietf-ntp-ntpv4-proto-08.txt
	Pages		: 108
	Date		: 2007-11-19
	
The Network Time Protocol (NTP) is widely used to synchronize
    computer clocks in the Internet.  This document describes NTP Version
    4 (NTPv4), which is backwards compatible with NTP Version 3 (NTPv3)
    described in RFC 1305, as well as previous versions of the protocol.
    NTPv4 includes a modified protocol header to accommodate the Internet
    Protocol Version 6 address family.  NTPv4 includes fundamental
    improvements in the mitigation and discipline algorithms which extend
    the potential accuracy to the tens of microseconds with modern
    workstations and fast LANs.  It includes a dynamic server discovery
    scheme, so that in many cases specific server configuration is not
    required.  It corrects certain errors in the NTPv3 design and
    implementation and includes an optional extension mechanism.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-ntp-ntpv4-proto-08.txt

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---

From: <[email-masked]>
Date: Sun, 25 Nov 2007 09:47:25 -0600

Brian,

Actually, I believe there was rough consensus around the use of the
first bit of the start of frame regardless of protocol. I certainly
agree this is the best point and only offered the option I did because
of my perception of it's probability of achieving consensus.

What I'm not sure of is whether there is consensus around including text
at the end of section 4 "Definitions."  I'd offer: "The timestamp
reference point is the leading edge of the first bit of the start of the
IP frame." as the text to include at that point. 

I don't know if it's too late or sufficiently critical to decide at this
late date.  I was primarily responding to a comment by Stewart (or was
it Yakov) in Chicago, though there is value in this issue for a number
of applications that interest me.  

While I'd like to see this resolved, I don't see earth shattering
consequences if it's not. 

Rich

> -----Original Message-----
> From: ntpwg-bounces+rich.osman=[email-masked] 
> [mailto:ntpwg-bounces+rich.osman=[email-masked]] On 
> Behalf Of ext Brian Haberman
> Sent: Tuesday, November 20, 2007 8:32 AM
> To: NTP Working Group
> Subject: [ntpwg] Updated NTPv4 Protocol Specification
> 
> NTP WG,

---

From: "David L. Mills" <[email-masked]>
Date: Mon, 26 Nov 2007 20:14:10 +0000

RIch, Brian,

Consensus or not, we are all victims of engineering necessity. The index 
point cannot be the first bit of the SOF; the hardware doesn't know it 
is an SOF until reading all bits of the SOF itself. The index must be 
immediately following the last bit and before the first bit of the frame 
itself. The index cannot be within the frame itself, because that would 
require the hardware to parse the frame on the wire, and that's just not 
practical.

The text should clearly state that the hardware protocol (PHY) must 
define in a media-specific manner the index point. The discussion here 
is relevant to Ethernet, but what about WiFi, FDDI, space communication, 
etc.? I think a statement something like that belongs in the spec; 
however, the SOF for Ethernet should be mentioned as example, not a 
definition.

Dave