draft-ietf-avtcore-leap-second-05.txt   draft-ietf-avtcore-leap-second-06.txt 
AVTCore K. Gross AVTCore K. Gross
Internet-Draft AVA Networks Internet-Draft AVA Networks
Updates: 3550 (if approved) R. van Brandenburg Updates: 3550 (if approved) R. van Brandenburg
Intended status: Standards Track TNO Intended status: Standards Track TNO
Expires: April 04, 2014 October 01, 2013 Expires: May 19, 2014 November 15, 2013
RTP and Leap Seconds RTP and Leap Seconds
draft-ietf-avtcore-leap-second-05 draft-ietf-avtcore-leap-second-06
Abstract Abstract
This document discusses issues that arise when RTP sessions span This document discusses issues that arise when RTP sessions span
Coordinated Universal Time (UTC) leap seconds. It updates RFC 3550 Coordinated Universal Time (UTC) leap seconds. It updates RFC 3550
to describe how RTP senders and receivers should behave in the to describe how RTP senders and receivers should behave in the
presence of leap seconds. presence of leap seconds.
Status of This Memo Status of This Memo
skipping to change at page 1, line 34 skipping to change at page 1, line 34
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 04, 2014. This Internet-Draft will expire on May 19, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 5, line 48 skipping to change at page 5, line 48
leap seconds. NTP time, operating system clocks and other UTC leap seconds. NTP time, operating system clocks and other UTC
references include leap seconds. references include leap seconds.
All participants working to a leap-second-bearing reference SHOULD All participants working to a leap-second-bearing reference SHOULD
recognize leap seconds and have a working communications channel to recognize leap seconds and have a working communications channel to
receive notification of leap-second scheduling. Note that a working receive notification of leap-second scheduling. Note that a working
communication channel includes a protocol means of notifying clocks communication channel includes a protocol means of notifying clocks
of an impending leap second such as the Leap Indicator in the NTP of an impending leap second such as the Leap Indicator in the NTP
header [8] but also a means for top-tier clocks to receive leap- header [8] but also a means for top-tier clocks to receive leap-
second schedule information published by the International Earth second schedule information published by the International Earth
Rotation and Reference Systems Service. Rotation and Reference Systems Service. [12]
Because of the timestamp ambiguity, positive leap seconds can Because of the timestamp ambiguity, positive leap seconds can
introduce and the inconsistent manner in which different systems introduce and the inconsistent manner in which different systems
accommodate positive leap seconds, generating or using NTP timestamps accommodate positive leap seconds, generating or using NTP timestamps
during the entire last second of a day on which a positive leap during the entire last second of a day on which a positive leap
second has been scheduled SHOULD be avoided. Note that the period to second has been scheduled SHOULD be avoided. Note that the period to
be avoided has a real-time duration of two seconds. In the Table 1 be avoided has a real-time duration of two seconds. In the Table 1
example, the region to be avoided is indicated by RTP timestamps example, the region to be avoided is indicated by RTP timestamps
12000 through 28000 12000 through 28000
skipping to change at page 7, line 43 skipping to change at page 7, line 43
[1] Schulzrinne, H., Casner, S., Frederick, R., and V. [1] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003. Applications", STD 64, RFC 3550, July 2003.
[2] Bradner, S., "Key words for use in RFCs to Indicate [2] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
9.2. Informative References 9.2. Informative References
[3] Institute of Electrical and Electronics Engineers, [3] IEEE, "IEEE Standard for Information Technology - Portable
"Portable Operating System Interface (POSIX)", IEEE Operating System Interface (POSIX)", IEEE Standard
Standard 1003.1, 2008. 1003.1-2008, 2008, <http://standards.ieee.org/findstds/
standard/1003.1-2008.html>.
[4] Google, Inc., "Time, technology and leaping seconds", [4] Google, Inc., "Time, technology and leaping seconds",
September 2011, <http://googleblog.blogspot.com/2011/09/ September 2011, <http://googleblog.blogspot.com/2011/09/
time-technology-and-leaping-seconds.html>. time-technology-and-leaping-seconds.html>.
[5] Kuhn, M., "Coordinated Universal Time with Smoothed Leap [5] Kuhn, M., "Coordinated Universal Time with Smoothed Leap
Seconds (UTC-SLS)", draft-kuhn-leapsecond-00 (work in Seconds (UTC-SLS)", draft-kuhn-leapsecond-00 (work in
progress), January 2006. progress), January 2006.
[6] ITU-R, "Recommendation ITU-R TF.460-6 - Standard-frequency [6] ITU, "Standard-frequency and time-signal emissions", ITU-R
and time-signal emissions", February 2002. TF.460-6, February 2002,
<http://www.itu.int/rec/R-REC-TF.460/>.
[7] ITU-R Working Party 7A, "Question SG07.236", February [7] ITU, "Question 236/7", February 2012,
2012. <http://www.itu.int/pub/R-QUE-SG07.236-2001>.
[8] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network [8] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010. Specification", RFC 5905, June 2010.
[9] IEEE, "IEEE Standard for a Precision Clock Synchronization [9] IEEE, "IEEE Standard for a Precision Clock Synchronization
Protocol for Networked Measurement and Control Systems", Protocol for Networked Measurement and Control Systems",
July 2008. IEEE Standard 1588-2008, July 2008, <http://
standards.ieee.org/findstds/standard/1588-2008.html>.
[10] Global Positioning Systems Directorate, "Navstar GPS Space [10] Global Positioning Systems Directorate, "Navstar GPS Space
Segment/Navigation User Segment Interfaces", September Segment/Navigation User Segment Interfaces", September
2011. 2011, <http://www.navcen.uscg.gov/pdf/IS-GPS-200F.pdf>.
[11] BIPM, "Circular T", May 2012. [11] Bureau International des Poids et Mesures (BIPM),
"International Atomic Time", November 2013,
<http://www.bipm.org/en/scientific/tai/tai.html>.
[12] International Earth Rotation and Reference System Service,
"Bulletin C", November 2013, <http://datacenter.iers.org/
web/guest/eop/-/somos/5Rgv/product/16>.
Authors' Addresses Authors' Addresses
Kevin Gross Kevin Gross
AVA Networks AVA Networks
Boulder, CO Boulder, CO
US US
Email: kevin.gross@avanw.com Email: kevin.gross@avanw.com
Ray van Brandenburg Ray van Brandenburg
TNO TNO
Brassersplein 2 Brassersplein 2
Delft 2612CT Delft 2612CT
the Netherlands the Netherlands
Phone: +31-88-866-7000 Phone: +31-88-866-7000
Email: ray.vanbrandenburg@tno.nl Email: ray.vanbrandenburg@tno.nl
 End of changes. 11 change blocks. 
15 lines changed or deleted 23 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/