Subject: [TICTOC] Proposed charter

From: Mark Townsley <[email-masked]>
Date: Fri, 30 Nov 2007 04:57:47 +0100

I performed a rather significant fleshing out of the proposed charter, 
and would like people to read and comment on this before the tictoc BoF. 
I tried to tighten up what the expected deliverables are just a bit, and 
biased some of the expectations with respect to 1588 and NTP here while 
still leaving the door open to variance if the WG decides otherwise 
based on the requirements analysis. Note that if tictoc is chartered, 
much of the work beyond documenting the deployed NTPv4 protocol in the 
NTP WG would transition here.

Thanks, and see you in Vancouver,

- Mark

Proposed Charter

Description of Working Group:

The Timing over IP Connections and Transfer Of Clock (tictoc) WG is 
concerned with highly accurate time and frequency distribution over 
native IP and MPLS-enabled IP Packet Switched Networks (PSNs). The 
degree of accuracy required naturally varies by application, but at a 
minimum the WG aims to improve on that which is generally available via 
NTP over the public Internet. While the need for this level of 
functionality arises from a variety of sources, the focus of this WG is 
on (1) service providers migrating services from TDM networks onto IP 
and MPLS PSNs, and (2) individual hosts and devices on the Internet 
requiring functionality or performance not available in NTP. The WG will 
develop requirements based on these focus areas, analyze solutions in a 
modular fashion based on system-level functionality, extend existing 
mechanisms where necessary, and define new functionality in as common a 
manner as feasible.

Specifically, TICTOC will address three use cases for timing distribution:

1. Time and frequency distribution within a well-engineered service 
provider or enterprise campus network, including possible on-path 
support at one or more hops on a given path
2. Time and frequency distribution to individual hosts and devices over 
the public Internet
3. The combined case of distribution of time and frequency from a master 
to the edge of a service provider network, and subsequently over an 
access network to an individual end host or device.

The NTP Working Group is currently standardizing the fourth version of 
NTP for time distribution over IP networks, including the public 
Internet. The NTP WG has focused its deliverables largely on 
standardizing the currently deployed NTPv4, while collecting 
requirements for future extensions. The IEEE has produced a second 
version of 1588, which is emerging as a viable solution for time 
transfer over service provider and campus networks, and for which 
specialized hardware support is becoming available. The TICTOC WG will 
document the requirements for high accuracy time and frequency 
distribution, and will document the extent to which these requirements 
can be satisfied with no modification to these currently available 
solutions. It is expected that to meet all of the requirements for high 
accuracy time and frequency distribution over PSNs, some extension of 
one or both of these protocols will be necessary. Ultimately, it is this 
gap analysis of requirements that will drive which solution to begin 
with and extend for each use-case.

IEEE 1588v2 specifically encourages other standards organizations to 
adapt it to their requirements, and provides guidelines for doing so. If 
1588v2 is ultimately recommended for any one of the use-cases set forth 
above, a suitable 1588v2 adaptation profile will be developed following 
the guidelines given by the IEEE. To date, 1588v2 has been targeted for 
use within well-engineered, closed, network environments, thus use-case 
#1 is expected to be the most logical case for a profile of 1588v2 to be 
applied. An applicability statement will describe the use-case for which 
any adaptation profile of 1588v2 is targeted.

TICTOC will adopt and extend NTPv4 as required to meet the use-cases set 
forth above. This may include revision of the protocol to a new version 
level, but in all cases backwards compatibility and the ability to 
co-exist with currently deployed NTPv4 is of paramount concern. Unlike 
1588v2, NTPv4 was designed to operate over the public Internet, thus use 
case #2 is expected to be the most logical case for a new version of NTP 
to target. This does not prevent NTP from operating in a closed network 
environment, but the primary focus of NTP will likely be the public 
Internet. An applicability statement will describe the use-case for 
which any extension of NTP is targeted.

TICTOC will not assume the availability of on-path support for time 
distribution, but will be able to exploit such support where it is 
available. Within a service provider network environment in particular, 
it may be advantageous to allow timing distribution traffic to take 
advantage of enhancements provided by specific intermediate network 
elements along a given path.

The TICTOC work must be modular and allow for component replacement in 
the future. In addition to the chosen timing distribution protocols, 
such modules include the transport mechanism over which the timing 
distribution protocol is carried; algorithms for frequency acquisition, 
ranging, and packet selection/discard; protocols for autodiscovery, 
master clock selection, path selection, OAM, synchronization status 
messaging, and performance monitoring; security mechanisms; and network 
management. This modular framework will be a deliverable of the WG in 
its first phase, though not all items will be addressed until after 
first phase deliverables are completed.

The TICTOC WG will co-ordinate with the PWE3 and NTP WGs in the IETF, as 
well as IEEE 1588, IEEE 802.1AS and ITU-T SG15 Q13. TICTOC will propose 
the formation of an IRTF RG to study more advanced aspects of timing 
distribution.

WG Objectives:

First phase objectives:

To document the time and frequency requirements of the services that 
need to be supported over a PSN for the three use-cases stated above.

To document a modular breakdown of functionality based on these 
requirements.

To determine the extent to which these requirements can be satisfied 
using IEEE 1588v2 and NTPv4 within each use-case, along with an 
associated gap analysis for what requirements are not met without 
adaptation or extension of these protocols.

To develop a 1588v2 profile as necessary for time and frequency 
distribution, likely with primary focus on use case #1.

To develop extensions to NTPv4 as necessary for time and frequency 
distribution, likely with primary focus on use case #2.

If required, to develop a 1588-NTP interworking mechanism for use case #3.

To provide applicability statements for all WG deliverables.

Second phase deliverables:

To propose and document algorithms, protocols and mechanisms for 
transport, frequency acquisition, ranging, and packet selection/discard, 
master clock selection, path selection, OAM, synchronization status 
messaging, performance monitoring, security, and network management.

Goals and Milestones:

Dates are for documents exiting WG last call, and entering "Publication 
Requested" with the shepherding Area Director.

March 08 - Problem statement, including documentation of use cases 
outlined in charter
March 08 - Modular Framework documentation
June 08 - Requirements analysis for use cases, including gap analysis 
for NTPv4 and 1588v2
Dec 08 - 1588v2 profile, if needed
Dec 08 - NTPv4 extensions, if needed
Mar 09 - MIB for IEEE 1588v2 profile and NTPv4 extensions (tictoc MIB)
Mar 09 - Prioritize second phase deliverables and add milestones or 
recharter.

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