draft-ietf-ippm-twamp-time-format-01.txt   draft-ietf-ippm-twamp-time-format-02.txt 
Network Working Group G. Mirsky Network Working Group G. Mirsky
Internet-Draft Internet-Draft
Intended status: Standards Track I. Meilik Intended status: Standards Track I. Meilik
Expires: May 9, 2017 Broadcom Expires: August 29, 2017 Broadcom
November 8, 2016 February 25, 2017
Support of IEEE-1588 time stamp format in Two-Way Active Measurement Support of IEEE-1588 time stamp format in Two-Way Active Measurement
Protocol (TWAMP) Protocol (TWAMP)
draft-ietf-ippm-twamp-time-format-01 draft-ietf-ippm-twamp-time-format-02
Abstract Abstract
This document describes an OPTIONAL feature for active performance This document describes an OPTIONAL feature for active performance
measurement protocols allowing use of time stamp format defined in measurement protocols allowing use of the Precision Time Protocol
IEEE-1588v2-2008. time stamp format defined in IEEE-1588v2-2008, as an alternative to
the Network Time Protocol that is currently used.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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
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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 May 6, 2017. This Internet-Draft will expire on August 29, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2017 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
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skipping to change at page 2, line 48 skipping to change at page 2, line 50
NTP domain or via interprocess communication in multiprocessor NTP domain or via interprocess communication in multiprocessor
distributed system. And of mentioned solutions will be subject to distributed system. And of mentioned solutions will be subject to
additional queuing delays that negatively affect data plane clock additional queuing delays that negatively affect data plane clock
accuracy. accuracy.
Precision Time Protocol (PTP) [IEEE.1588.2008] has gained wide Precision Time Protocol (PTP) [IEEE.1588.2008] has gained wide
support since the development of OWAMP and TWAMP. PTP, using on-path support since the development of OWAMP and TWAMP. PTP, using on-path
support and other mechanisms, allows sub-microsecond clock accuracy. support and other mechanisms, allows sub-microsecond clock accuracy.
PTP is now supported in multiple implementations of fast forwarding PTP is now supported in multiple implementations of fast forwarding
engines and thus accuracy achieved by PTP is the accuracy of clock in engines and thus accuracy achieved by PTP is the accuracy of clock in
data plane. Thus, providing option to use more accurate clock as data plane. An option to use a more accurate clock as a source of
source of time stamps for IP performance measurement is one of time stamps for IP performance measurements is one of this proposal?s
advantages this proposal helps to achieve. Another advantage realized advantages. Another advantage is realized by simplification of
by simplification of hardware in data plane. To support OWAMP or hardware in data plane. To support OWAMP or TWAMP test protocol time
TWAMP test protocol time stamps must be converted from PTP to NTP. stamps must be converted from PTP to NTP. That requires resources,
use of micro-code or additional processing elements, that are always
That requires resources, use of micro-code or additional processing limited. To address this, this document proposes optional extensions
elements, that are always limited. To address this, this document to Control and Test protocols to support use of IEEE-1588v2 time
proposes optional extensions to Control and Test protocols to support stamp format as optional alternative to the NTP time stamp format.
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 One of the goals of this proposal is not only to allow end-points of
test session to use other than NTP timestamp but to support backwards a test session to use timestamp format other than NTP but to support
compatibility with nodes that do not yet support this extension. backwards compatibility with nodes that do not yet support this
extension.
1.1. Conventions used in this document 1.1. Conventions used in this document
1.1.1. Terminology 1.1.1. Terminology
IPPM: IP Performance Measurement IPPM: IP Performance Measurement
NTP: Network Time Protocol NTP: Network Time Protocol
PTP: Precision Time Protocol PTP: Precision Time Protocol
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
2. OWAMP and TWAMP Extensions 2. OWAMP and TWAMP Extensions
OWAMP connection establishment follows the procedure defined in OWAMP connection establishment follows the procedure defined in
Section 3.1 of [RFC4656] and additional steps in TWAMP described 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 Section 3.1 of [RFC5357]. In these procedures, the Modes field been
used to identify and select specific communication capabilities. At used to identify and select specific communication capabilities. At
the same time the Modes field been recognized and used as extension the same time the Modes field has been recognized and used as
mechanism [RFC6038]. The new feature requires one bit position for extension mechanism [RFC6038]. The new feature requires one bit
Server and Control-Client to negotiate which timestamp format can be position for Server and Control-Client to negotiate which timestamp
used in some or all test sessions invoked with this control format can be used in some or all test sessions invoked with this
connection. The end-point of the test session, Session-Sender and control connection. The end-point of the test session, Session-
Session-Receiver or Session-Reflector, that supports this extension Sender and Session-Receiver or Session-Reflector, that supports this
MUST be capable to interpret NTP and PTPv2 timestamp formats. If the extension MUST be capable to interpret NTP and PTPv2 timestamp
end-point does not support this extension, then the value of PTPv2 formats. If the end-point does not support this extension, then the
Timestamp flag MUST be 0 because it is in Must Be Zero field. If value of PTPv2 Timestamp flag MUST be 0 because it is in Must Be Zero
value of PTPv2 Timestamp flags is 0, then the advertising node can field. If the value of PTPv2 Timestamp flags is 0, then the
use and interpret only NTP timestamp format. advertising node can use and interpret only NTP timestamp format.
Use of PTPv2 Timestamp flags discussed in the following sub-sections. Use of PTPv2 Timestamp flags is discussed in the following sub-
For details on the assigned values and bit positions see the sections. For details on the assigned values and bit positions see
Section 3. the Section 3.
2.1. Timestamp Format Negotiation in Setting Up Connection in OWAMP 2.1. Timestamp Format Negotiation in Setting Up Connection in OWAMP
In OWAMP-Test [RFC4656] it is the Session-Receiver and/or Fetch- In OWAMP-Test [RFC4656] the Session-Receiver and/or Fetch-Client
Client that are interpreting collected timestamps. Thus, announced by interpret collected timestamps. Thus, the Server uses the Modes
a Server in the Modes field timestamp format indicates which formats field timestamp format to indicate which formats the Session-Receiver
the Session-Receiver is capable to interpret. The Control-Client is capable to interpret. The Control-Client inspects values set by
inspects values set by the Server for timestamp formats and sets the Server for timestamp formats and sets values in the Modes field
values in the Modes field of the Set-Up-Response message per of the Set-Up-Response message according to timestamp formats
timestamp formats Session-Sender can use. The rules of setting Session-Sender can use. The rules of setting timestamp flags in
timestamp flags in Modes field in server greeting and Set-Up- Modes field in server greeting and Set-Up-Response messages and
Response messages and interpreting them are as follows: interpreting them are as follows:
o The Server that establishes test sessions for Session-Receiver o The Server that establishes test sessions for Session-Receiver
that supports this extension MUST set PTPv2 Timestamp flag to 1 in that supports this extension MUST set PTPv2 Timestamp flag to 1 in
the server greeting message per the requirement listed in the server greeting message per the requirement listed in
Section 2. Section 2.
o If PTPv2 Timestamp flag of the server greeting message that the o If PTPv2 Timestamp flag of the server greeting message that the
Control-Client receives has value 0, then the Session-Sender MUST Control-Client receives has value 0, then the Session-Sender MUST
use NTP format for timestamp in the test session and Control- use NTP format for timestamp in the test session and Control-
Client SHOULD set PTPv2 Timestamp flag to 0 in accordance with Client SHOULD set PTPv2 Timestamp flag to 0 in accordance with
[RFC4656]. If the Session-Sender cannot use NTP timestamps, then [RFC4656]. If the Session-Sender cannot use NTP timestamps, then
the Control-Client SHOULD close the TCP connection associated with the Control-Client SHOULD close the TCP connection associated with
the OWAMP-Control session. the OWAMP-Control session.
o If the Session-Sender can set timestamp in PTPv2 format, then the o If the Session-Sender can set timestamp in PTPv2 format, then the
Control-Client MUST set the PTPv2 Timestamp flag to 1in Modes Control-Client MUST set the PTPv2 Timestamp flag to 1 in Modes
field in the Set-Up-Response message and the Session-Sender MUST field in the Set-Up-Response message and the Session-Sender MUST
set timestamp in PTPv2 timestamp format. Otherwise the Control- set timestamp in PTPv2 timestamp format. Otherwise the Control-
Client MUST set the PTPv2 Timestamp flag in the Set-Up-Response Client MUST set the PTPv2 Timestamp flag in the Set-Up-Response
message to 0. message to 0.
o Otherwise, if the Session-Sender can set timestamp in NTP format, o Otherwise, if the Session-Sender can set timestamp in NTP format,
then the Session-Sender MUST set timestamp in NTP timestamp then the Session-Sender MUST set timestamp in NTP timestamp
format. Otherwise the Control-Client SHOULD close the TCP format. Otherwise the Control-Client MUST close the TCP
connection associated with the OWAMP-Control session. connection associated with the OWAMP-Control session.
If values of both NTP and PTPv2 Timestamp flags in the Set-Up- If values of both NTP and PTPv2 Timestamp flags in the Set-Up-
Response message are equal to 0, then that indicates that the Response message are equal to 0, then that indicates that the
Control-Client can set timestamp only in NTP format. Control-Client can set timestamp only in NTP format.
If OWAMP-Control uses Fetch-Session commands, then selection and use If OWAMP-Control uses Fetch-Session commands, then selection and use
of one or another timestamp format is local decision for both of one or another timestamp format is local decision for both
Session-Sender and Session-Receiver. Session-Sender and Session-Receiver.
2.2. Timestamp Format Negotiation in Setting Up Connection in TWAMP 2.2. Timestamp Format Negotiation in Setting Up Connection in TWAMP
In TWAMP-Test [RFC5357] it is the Session-Sender that is interpreting In TWAMP-Test [RFC5357] the Session-Sender interprets collected
collected timestamps. Hence, in the Modes field a Server advertises timestamps. Hence, in the Modes field a Server advertises timestamp
timestamp formats that the Session-Reflector can use in TWAMP-Test formats that the Session-Reflector can use in TWAMP-Test message.
message. The choice of the timestamp format to be used by the The choice of the timestamp format to be used by the Session-Sender
Session-Sender is a local decision. The Control-Client inspects the is a local decision. The Control-Client inspects the Modes field and
Modes field and sets timestamp flags values to indicate which format sets timestamp flags values to indicate which format will be used by
will be used by the Session-Reflector. The rules of setting and the Session-Reflector. The rules of setting and interpreting flag
interpreting flag values are as follows: values are as follows:
o Server MUST set to 1 value of PTPv2 Timestamp flag in its greeting o Server MUST set to 1 value of PTPv2 Timestamp flag in its greeting
message if Session-Reflector can set timestamp in PTPv2 format. message if Session-Reflector can set timestamp in PTPv2 format.
Otherwise the PTPv2 Timestamp flag MUST be set to 0. Otherwise the PTPv2 Timestamp flag MUST be set to 0.
o If value of the PTPv2 Timestamp flag in received server greeting o If value of the PTPv2 Timestamp flag in received server greeting
message equals 0, then Session-Reflector does not support this message equals 0, then Session-Reflector does not support this
extension and will use NTP timestamp format. Control-Client extension and will use NTP timestamp format. Control-Client
SHOULD set PTPv2 Timestamp flag to 0 in Set-Up-Response message in SHOULD set PTPv2 Timestamp flag to 0 in Set-Up-Response message in
accordance with [RFC5357]. accordance with [RFC5357].
o Control-Client MUST set PTPv2 Timestamp flag value to 1 in Modes o Control-Client MUST set PTPv2 Timestamp flag value to 1 in Modes
field in the Set-Up-Response message if Server advertised ability field in the Set-Up-Response message if Server advertised ability
of the Session-Reflector to use PTPv2 format for timestamps. of the Session-Reflector to use PTPv2 format for timestamps.
Otherwise the flag MUST be set to 0. Otherwise the flag MUST be set to 0.
o If the values of PTPv2 Timestamp flag in the Set-Up-Response o If the values of PTPv2 Timestamp flag in the Set-Up-Response
message equals 0, then that means that Session-Sender can only message equals 0, then that means that Session-Sender can only
interpret NTP timestamp format. Then the Session-Reflector MUST interpret NTP timestamp format. Then the Session-Reflector MUST
use NTP timestamp format. If the Session-Reflector does not use NTP timestamp format. If the Session-Reflector does not
support NTP format for timestamps then Server and SHOULD close the support NTP format then Server and MUST close the TCP connection
TCP connection associated with the TWAMP-Control session. associated with the TWAMP-Control session.
2.3. OWAMP-Test and TWAMP-Test Update 2.3. OWAMP-Test and TWAMP-Test Update
Participants of a test session need to indicate which timestamp Participants of a test session need to indicate which timestamp
format being used. The proposal is to use Z field in Error Estimate 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 defined in Section 4.1.2 of [RFC4656]. The new interpretation of the
Error Estimate is in addition to it specifying error estimate and Error Estimate is in addition to it specifying error estimate and
synchronization, Error Estimate indicates format of a collected synchronization, Error Estimate indicates format of a collected
timestamp. And this proposal changes the semantics of the Z bit timestamp. And this proposal changes the semantics of the Z bit
field, the one between S and Scale fields, to be referred as field, the one between S and Scale fields, to be referred as
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