One document matched: draft-mirsky-ippm-time-format-00.txt
Network Working Group G. Mirsky
Internet-Draft R. Lakshmikanthan
Intended status: Standards Track S. Bansal
Expires: July 20, 2015 Ericsson
I. Meilik
Broadcom
January 16, 2015
Support of IEEE-1588 time stamp format in Two-Way Active Measurement
Protocol (TWAMP)
draft-mirsky-ippm-time-format-00
Abstract
This document describes an OPTIONAL feature for active performance
measurement protocols allowing use of time stamp format defined in
IEEE-1588v2-2008.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 20, 2015.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
Mirsky, et al. Expires July 20, 2015 [Page 1]
Internet-Draft 1588 time stamp format in TWAMP January 2015
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
2. OWAMP and TWAMP Extensions . . . . . . . . . . . . . . . . . 3
2.1. Timestamp Format Negotiation in Setting Up Connection in
OWAMP . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Timestamp Format Negotiation in Setting Up Connection in
TWAMP . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. OWAMP-Test and TWAMP-Test Update . . . . . . . . . . . . 6
2.3.1. Consideration for TWAMP Light mode . . . . . . . . . 6
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
6. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
One-Way Active Measurement Protocol (OWAMP) [RFC4656] defines that
only the NTP [RFC5905] format of a time stamp can be used in OWAMP-
Test protocol. Two-Way Active Measurement Protocol (TWAMP) [RFC5357]
adopted the OWAMP-Test packet format and extended it by adding a
format for a reflected test packet. Both the sender's and
reflector's packets time stamps are expected to follow the 64-bit
long NTP format [RFC5905].
Precision Time Protocol (PTP) [IEEE.1588.2008] has gained wide
support since the development of OWAMP and TWAMP. PTP is now
supported in multiple implementations of fast forwarding engines. As
result, to support OWAMP or TWAMP test protocol time stamps must be
converted from PTP to NTP. That requires resources, use of micro-
code or additional processing elements, that are always limited. To
address this, this document proposes optional extensions to Control
and Test protocols to support use of IEEE-1588v2 time stamp format as
optional alternative to the NTP time stamp format.
One of the goals of this proposal is not only allow end-points of a
test session to use other than NTP timestamp but to support backwards
compatibility with nodes that do not yet support this extension.
Mirsky, et al. Expires July 20, 2015 [Page 2]
Internet-Draft 1588 time stamp format in TWAMP January 2015
1.1. Conventions used in this document
1.1.1. Terminology
IPPM: IP Performance Measurement
NTP: Network Time Protocol
PTP: Precision Time Protocol
TWAMP: Two-Way Active Measurement Protocol
OWAMP: One-Way Active Measurement Protocol
1.1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
2. OWAMP and TWAMP Extensions
OWAMP connection establishment follows the procedure defined in
Section 3.1 of [RFC4656] and additional steps in TWAMP described in
Section 3.1 of [RFC5357]. In these procedures the Modes field been
used to identify and select specific communication capabilities. At
the same time the Modes field been recognized and used as extension
mechanism [RFC6038]. The new feature requires two bit positions for
Server and Control-Client to negotiate which timestamp format can be
used in some or all test sessions invoked with this control
connection. The end-point of the test session, Session-Sender and
Session-Receiver or Session-Reflector, that supports this extension
MUST be capable to interpret NTP and PTPv2 timestamp formats. If the
end-point does not support this extension, then the value of NTP
Timestamp and PTPv2 Timestamp flags MUST be 0 because it is in Must
Be Zero field. If value of both NTP and PTPv2 Timestamp flags is 0,
then the advertising node can use and interpret only NTP timestamp
format.
Use of two other flags, NTP Timestamp and PTPv2 Timestamp flags
discussed in the following sub-sections. For details on the assigned
values and bit positions see the Section 3.
Mirsky, et al. Expires July 20, 2015 [Page 3]
Internet-Draft 1588 time stamp format in TWAMP January 2015
2.1. Timestamp Format Negotiation in Setting Up Connection in OWAMP
In OWAMP-Test [RFC4656] it is the Session-Receiver and/or Fetch-
Client that are interpreting collected timestamps. Thus announced by
a Server in the Modes field timestamp format indicates which formats
the Session-Receiver is capable to interpret. The Control-Client
inspects values set by the Server for timestamp formats and sets
values in the Modes field of the Set-Up-Response message according to
timestamp formats Session-Sender is capable of using. The rules of
setting timestamp flags in Modes field in server greeting and Set-Up-
Response messages and interpreting them are as follows:
o The Server that establishes test sessions for Session-Receiver
that supports this extension MUST set NTP Timestamp and PTPv2
Timestamp flags to 1 in the server greeting message according to
the requirement listed in Section 2.
o If NTP Timestamp and PTPv2 Timestamp flags of the server greeting
message that the Control-Client receives each has value 0, then
the Session-Sender MUST use NTP format for timestamp in the test
session and Control-Client SHOULD set NTP Timestamp and PTPv2
Timestamp flags to 0 in accordance with [RFC4656]. If the
Session-Sender cannot use NTP timestamps, then the Control-Client
SHOULD close the TCP connection associated with the OWAMP-Control
session.
o If the Session-Sender can set timestamp in PTPv2 format, then the
Control-Client MUST set the PTPv2 Timestamp flag to 1in Modes
field in the Set-Up-Response message and the Session-Sender MUST
set timestamp in PTPv2 timestamp format. Otherwise the Control-
Client MUST set the PTPv2 Timestamp flag in the Set-Up-Response
message to 0.
o If the value of the PTPv2 Timestamp flag in the Set-Up-Response
message is 1, then the Control-Client MUST set the NTP Timestamp
flag in the Set-Up-Response message to 0.
o Otherwise, if the Session-Sender can set timestamp in NTP format,
then the Control-Client MUST set the NTP Timestamp flag in the
Set-Up-Response message to 1 and the Session-Sender MUST set
timestamp in NTP timestamp format. Otherwise the Control-Client
SHOULD close the TCP connection associated with the OWAMP-Control
session..
If values of both NTP and PTPv2 Timestamp flags in the Set-Up-
Response message are equal to 0, then that indicates that the
Control-Client can set timestamp only in NTP format.
Mirsky, et al. Expires July 20, 2015 [Page 4]
Internet-Draft 1588 time stamp format in TWAMP January 2015
If OWAMP-Control uses Fetch-Session commands, then selection and use
of one or another timestamp format is local decision for both
Session-Sender and Session-Receiver.
2.2. Timestamp Format Negotiation in Setting Up Connection in TWAMP
In TWAMP-Test [RFC5357] it is the Session-Sender that is interpreting
collected timestamps. Hence, in the Modes field a Server advertises
timestamp formats that the Session-Reflector can use in TWAMP-Test
message. The choice of the timestamp format to be used by the
Session-Sender is a local decision. The Control-Client inspects the
Modes field and sets timestamp flags values to indicate which format
will be used by the Session-Reflector. The rules of setting and
interpreting flag values are as follows:
o Server MUST set to 1 value of NTP Timestamp flag in the greeting
message if Session-Reflector can set timestamp in NTP format.
Otherwise the NTP Timestamp flag MUST be set to 0.
o Server MUST set to 1 value of PTPv2 Timestamp flag in its greeting
message if Session-Reflector can set timestamp in PTPv2 format.
Otherwise the PTPv2 Timestamp flag MUST be set to 0.
o If values of both NTP Timestamp and PTPv2 Timestamp flags in
received server greeting message each equals 0, then Session-
Reflector does not support this extension and will use NTP
timestamp format. Control-Client SHOULD set NTP Timestamp and
PTPv2 Timestamp flags to 0 in Set-Up-Response message in
accordance with [RFC5357].
o Control-Client MUST set PTPv2 Timestamp flag value to 1 in Modes
field in the Set-Up-Response message if Server advertised ability
of the Session-Reflector to use PTPv2 format for timestamps.
Otherwise the flag MUST be set to 0.
o Control-Client MUST set NTP Timestamp flag value to 1 in Modes
field in the Set-Up-Response message if Server advertised ability
of the Session-Reflector to use NTP format for timestamps.
Otherwise the flag MUST be set to 0.
o If the values of both NTP Timestamp and PTPv2 Timestamp flags in
the in the Set-Up-Response message are both equal 0, then that
means that Session-Sender can only interpret NTP timestamp format.
Then the Session-Reflector MUST use NTP timestamp format. If the
Session-Reflector does not support NTP format for timestamps then
Server and SHOULD close the TCP connection associated with the
TWAMP-Control session.
Mirsky, et al. Expires July 20, 2015 [Page 5]
Internet-Draft 1588 time stamp format in TWAMP January 2015
2.3. OWAMP-Test and TWAMP-Test Update
Participants of a test session need to indicate which timestamp
format being used. The proposal is to use Z field in Error Estimate
defined in Section 4.1.2 of [RFC4656]. The new interpretation of the
Error Estimate is in addition to it specifying error estimate and
synchronization, Error Estimate indicates format of a collected
timestamp. And this proposal changes the semantics of the Z bit
field, the one between S and Scale fields, to be referred as
Timestamp format and value MUST be set according to the following:
o 0 - NTP 64 bit format of a timestamp;
o 1 - PTPv2 truncated format of a timestamp.
As result of this value of the Z field from Error Estimate, Sender
Error Estimate or Send Error Estimate and Receive Error Estimate
SHOULD NOT be ignored and MUST be used when calculating delay and
delay variation metrics based on collected timestamps.
2.3.1. Consideration for TWAMP Light mode
This document does not specify how Session-Sender and Session-
Reflector in TWAMP Light mode are informed of timestamp format to be
used. It is assumed that, for example, configuration could be used
to direct Session-Sender and Session-Reflector respectively to use
timestamp format according to their capabilities and rules listed in
Section 2.2.
3. IANA Considerations
The TWAMP-Modes registry defined in [RFC5618].
IANA is requested to reserve a new NTP Timestamp and PTPv2 Timestamp
as follows:
+--------------+------------------+---------------------+-----------+
| Value | Description | Semantics | Reference |
+--------------+------------------+---------------------+-----------+
| TBA1 | NTP Timestamp | bit position TBA2 | This |
| (proposed | Capability | (proposed 8) | document |
| 256) | | | |
| TBA2 | PTPv2 Timestamp | bit position TBA4 | This |
| (proposed | Capability | (proposed 9) | document |
| 512) | | | |
+--------------+------------------+---------------------+-----------+
Table 1: New Timestamp Capability
Mirsky, et al. Expires July 20, 2015 [Page 6]
Internet-Draft 1588 time stamp format in TWAMP January 2015
4. Security Considerations
Use of particular format of a timestamp in test session does not
appear to introduce any additional security threat to hosts that
communicate with OWAMP and/or TWAMP as defined in [RFC4656],
[RFC5357] respectively. The security considerations that apply to
any active measurement of live networks are relevant here as well.
See the Security Considerations sections in [RFC4656] and [RFC5357].
5. Acknowledgements
The authors would like to thank David Allan for his thorough review
and thoughtful comments.
6. Normative References
[IEEE.1588.2008]
"Standard for a Precision Clock Synchronization Protocol
for Networked Measurement and Control Systems", IEEE
Standard 1588, March 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, September 2006.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, October 2008.
[RFC5618] Morton, A. and K. Hedayat, "Mixed Security Mode for the
Two-Way Active Measurement Protocol (TWAMP)", RFC 5618,
August 2009.
[RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
[RFC6038] Morton, A. and L. Ciavattone, "Two-Way Active Measurement
Protocol (TWAMP) Reflect Octets and Symmetrical Size
Features", RFC 6038, October 2010.
Mirsky, et al. Expires July 20, 2015 [Page 7]
Internet-Draft 1588 time stamp format in TWAMP January 2015
Authors' Addresses
Greg Mirsky
Ericsson
Email: gregory.mirsky@ericsson.com
Ramanathan Lakshmikanthan
Ericsson
Email: ramanathan.lakshmikanthan@ericsson.com
Suchit Bansal
Ericsson
Email: suchit.bansal@ericsson.com
Israel Meilik
Broadcom
Email: israel@broadcom.com
Mirsky, et al. Expires July 20, 2015 [Page 8]
| PAFTECH AB 2003-2026 | 2026-04-22 22:58:04 |