Folks,
I've heard that my .txt file attachment was stripped off on some
systems. Here are the minutes in line for your review...
Karen
DRAFT (15 Aug 2011)
Minutes for TICTOC meeting @ IETF-80
28 July 2011, 15:20 EDT (19:20 UTC)
The meeting started at 15:20 EDT. Karen O'Donoghue and Yaakov Stein
chaired the meeting
Dave Marlow took minutes. Karen was jabber scribe.
Karen bashed the agenda and the blue sheets were distributed. Karen
provided the status
for the Working group since the last meeting: 3 working group drafts, 3
individual
submissions, and no interim meetings.
Stefano Ruffino provided slides for an ITU-T SG15/Q13 update which
Yaakov presented.
SG15/Q13 had an interim meeting in May 2011. There were two primary
topics of
interest to TICTOC: (1) Packet timing performance aspects for frequency
(G.826x series);
and (2)Time Sync in packet networks (G.827x series). The frequency work
is maturing
while the time/phase work has its requirements document (G.8271) updated
and other
documents are identified and being started. SG15/Q13 is also working on
a definition
and terminology document for both frequency and time of day (G.8260).
Yang Cui provided a Security Requirements discussion based on IPsec
security for packet
based synchronization,
draft-xu-tictoc-ipsec-security-for-synchronization-01. As described
by its Abstract, this document analyses the need for security methods
for synchronization
messages distributed over the Internet and gives a solution on how to
mark the
synchronization message when IPSec is implemented in end to end
frequency synchronization.
It was pointed out that the Introduction has requirements language (i.e.
SHALLs) and
these will need to be taken out of this section. There was
considerable discussion on
the IEEE 1588 PTP use case across the Internet where Yaakov and Greg
Dowd pointed out you
cannot have transparent clocks you must tunnel. On a discussion of
whether to encrypt
packets across 3GPP, someone from the jabber room pointed out that with
3GPP you must
encrypt. Yaakov asked whether the authors have talked with anyone in
the closing IPsec
WG about this draft and Yang indicated that he has and they do not have
any questions.
Karen asked whether the Working Group thought this work should be
pursued, but got little
feedback. Peter Lothberg said that in some use cases this could be
useful but this
provides no value for the Internet use case. Yang said that the
femtocell is getting
greater use and there is no protection in the femtocell. Greg Dowd said
that femtocells
are meant to provide telephone calls and that they can be stopped by
dropping all data.
He said we needed to clarify the threat models we are building the
security for.
Karen discussed time synchronization protocol security requirements.
The expired
TICTOC Requirements draft had recently been resubmitted
(draft-ietf-tictoc-requirements-01). This draft identifies three
security mechanisms to
consider. Karen went over a survey that was done at the beginning of
the TICTOC work
where four questions were identified that cover the different aspects
for possible
security services. Karen said that a volunteer editor has been
identified to work on
general time synchronization security requirements. The goal is to have
a draft by the
next meeting.
Greg Dowd provided a PTPv2 MIB discussion based on
draft-ietf-tictoc-ptp-mib-00. This
MIB goes beyond the earlier drafts that only covered the PTPv2 telecom
profile. This
MIB covers all the PTPv2 devices. The current draft is in its third
version and
Greg felt it was now semantically correct. Asked whether this MIB has
been deployed,
Greg said that it has. Measuring the performance of a PTPv2 node is
outside the
present scope, but this could be added later. Yaakov asked whether
there was
commonality between this MIB and the NTPv4 MIB (RFC 5907), Greg said
that this
MIB was PTPv2 specific with little commonality to the NTP MIB. Dave
Marlow said
that he had read the draft and found little commonality with the NTP MIB
but was
very supportive of this draft which appears very thorough. The Chairs
said that
there needs to be MIB Doctor review (which they would pursue) and review by
TICTOC participants for this draft to progress.
Yaakov lead a discussion on Transporting PTP messages (IEEE 1588) over
MPLS Networks,
draft-ietf-tictoc-1588overmpls-01. He said that the draft very mature
with three
individual drafts and now one TICTOC version. There has been
considerable discussion
on the list. Yaakov asked what was needed before this goes to WGLC?
Luca Martini
said that there are some text formatting issues and that some sections
have given a
a wrong impression. Of particular concern were the two modes (IP over
MPLS and
Pseudowire), Pseudowire is not needed if timing is a service of the
network and there
is only one clock over the network. Pseudowire is needed if PTP is used
directly over
Ethernet, and Yaakov pointed out that in many parts of the world there
are many clocks
that a carrier transports separately. There were some concerns from the
MPLS
community, George Swallow pointed out an issue with fast reroute to
address a fault.
There were concerns whether the draft was ready for last call or not,
and what
procedure should be taken to get comments from the MPLS community.
George suggested
to at least announce to the MPLS list about a WGLC in TICTOC.
Tal Mizrahi briefed UDP Checksum Trailer in Timing Protocols,
draft-mizrahi-tictoc-checksum-trailer-00. This draft proposes a
Checksum Trailer
extension to NTP, OWAMP and TWAMP that allows intermediate nodes to
reflect the
checksum modification in the last 2 octets of the packet rather than in
the UDP
checksum field. This is to bring a capability already in IEEE 1588 into
these other
protocols. Yaakov asked why this is being brought into OWAMP and
TWAMP. Tal said
these are performance protocols that transfer time and could be
benefited as well.
An issue related to the NTP extension field had been raised and
discussed on the
mailing list. This proposed technique requires an extension field without
authentication (i.e. without a MAC) to be practical; however, the NTPv4
spec
(i.e. RFC 5905) REQUIRES all extension fields to include authentication.
Discussion on the list included opinions that the RFC was wrong and this
is not
a requirement for NTPv4. Additional effort is needed to determine if
NTPv4 spec
should be changed or not. Yaakov pointed out that both OWAMP and TWAMP
have
authenticated modes. This draft is intended for non authenticated
packets only.
Yaakov said that in the case of OWAMP this is very limiting because its
default is
to be authenticated. In addition Yaakov said that OWAMP and TWAMP would
require
an extension to their control protocols. OWAMP and TWAMP are IPPM
protocols, the
Chairs took an action to send this draft to the IPPM chairs. Tal was asked
whether the mechanisms discussed in the draft had been implemented and he
said the mechanisms had not yet been implemented.
Dave Marlow discussed Network Time Mechanisms for Improving Computer
Clock Accuracy,
draft-marlow-tictoc-computer-clock-accuracy-00. This draft had not been
updated
since the last meeting but Dave briefed the discussion that had been on
the list.
Vladimir Smotlacha provided to the list, references to his papers
describing NTP
servers which use OCXO oscillators to achieve much higher
synchronization accuracy
than the experimental results described in this draft. The use case in
the draft
covers client accuracy and thus is outside the Vladimir's use case which
addresses
server accuracy. In June, Karen had forwarded a note from Dave Mills to
the list
which mentioned that additional experimental results with NTP Interleave
are in his
book. Dave Mill's book provides experimental results for both an
unloaded scenario
(which is a very similar to the experiment described in the draft) and a
loaded
scenario. Dave Mills, in his email, pointed out that Interleave showed
greater
improvement in the loaded scenarios and with digest computations (e.g.
Autokey).
Dave Marlow and Tim Plunkett are looking at the experimental results in
the book and
comparing this to their results. Tim Frost provided a paper on Minimum
Time-Dispersion
Metrics to the list. Dave indicated that this provides direction
towards identifying
a common set of metrics for network time synchronization experiments. A
common set of
metrics or perhaps a benchmarking draft could be a candidate for future
TICTOC work.
Greg Dowd said that there are products on the market that can provide a
hardware time
stamp based on a programmable sequence off of a packet data network,
this provides a
direction for the second mechanism outlined in the draft. Yaakov
mentioned that
his company tried NTP interleave on their highly optimized products and
did not
see a significant difference in performance. Dave said he and Tim
Plunkett would
like to update their draft with the new information. He solicited
comments and
contributions on mechanisms to achieve greater client accuracy.
Karen led an additional NTP discussion. The NTP control protocol which
is an
appendix of RFC 1305 (NTPv3) is not in a current standard since RFC 1305
was deprecated.
Volunteers are needed to get this important work documented and
standardized. Brian
Haberman (along with Karen, co-chair of the NTP working group) suggested
in line with
Dave Hart to get rid of mode 7 and just document mode 6. Harlan Stenn,
via jabber
requested that mode 7 be documented as well. Dave Hart, via jabber,
said that mode 7
is fragile and vendor specific, so that there is no use in standardizing
it. Harlan
volunteered to document the NTP control protocol. It was pointed out
that RFC 5905 needs
to be redone since mode 6 is identified for future use; however, if this
is an IANA
controlled field then just a change by IANA is needed. Karen asked for
volunteers to
document the NTP interleave extensions. There has been email on list
discussing Autokey
bugs/vulnerabilities being found by PTB (Germany's Standards
Organization). There were
no details discussed at this meeting but this is a concern that must be
followed. There
was a short discussion on what work would be carried out in the NTP WG
and what should
be done in the TICTOC WG. Brian said that all NTP control protocol work
should be done
in the NTP WG but he had no opinion at this time as to where Interleave
work should be
done. All co-chairs agreed that email on any NTP topic should be sent
to both lists.
The meeting adjourned at 17:20 EDT (21:20 UTC).
On 8/15/11 10:25 AM, Karen O'Donoghue wrote:
Folks,
Below are the draft minutes for the recent tictoc meeting. Thanks to
Dave Marlow for the timely production of the minutes. Please review
and submit any comments or changes as soon as possible.
Regards,
Karen
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https://www.ietf.org/mailman/listinfo/tictoc
