draft-ietf-ippm-twamp-reflect-octets-09.txt   rfc6038.txt 
Network Working Group A. Morton Internet Engineering Task Force (IETF) A. Morton
Internet-Draft L. Ciavattone Request for Comments: 6038 L. Ciavattone
Updates: 5357 (if approved) AT&T Labs Updates: 5357 AT&T Labs
Intended status: Standards Track August 17, 2010 Category: Standards Track October 2010
Expires: February 18, 2011 ISSN: 2070-1721
TWAMP Reflect Octets and Symmetrical Size Features Two-Way Active Measurement Protocol (TWAMP) Reflect Octets and
draft-ietf-ippm-twamp-reflect-octets-09 Symmetrical Size Features
Abstract Abstract
This memo describes two closely-related features for the core This memo describes two closely related features for the core
specification of TWAMP - the Two-Way Active Measurement Protocol: an specification of the Two-Way Active Measurement Protocol (TWAMP): an
optional capability where the responding host returns some of the optional capability where the responding host returns some of the
command octets or padding octets to the sender, and an optional command octets or padding octets to the sender, and an optional
sender packet format that ensures equal test packet sizes are used in sender packet format that ensures equal test packet sizes are used in
both directions. both directions.
Requirements Language Status of This Memo
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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 This is an Internet Standards Track document.
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 This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on February 18, 2011. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6038.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 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 3, line 7 skipping to change at page 2, line 19
modifications of such material outside the IETF Standards Process. modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other it for publication as an RFC or to translate it into languages other
than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction ....................................................3
2. Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Language ...........................................3
3. TWAMP Control Extensions . . . . . . . . . . . . . . . . . . . 5 3. Purpose and Scope ...............................................4
3.1. Connection Setup with New Features . . . . . . . . . . . . 5 4. TWAMP Control Extensions ........................................4
3.2. Reflect Octets: Request-TW-Session Packet Format . . . . . 6 4.1. Connection Setup with New Features .........................5
3.3. Reflect Octets: Accept Session Packet Format . . . . . . . 8 4.2. Reflect Octets: Request-TW-Session Packet Format ...........6
3.4. Additional considerations . . . . . . . . . . . . . . . . 10 4.3. Reflect Octets: Accept Session Packet Format ...............7
4. Extended TWAMP Test . . . . . . . . . . . . . . . . . . . . . 10 4.4. Additional Considerations ..................................9
4.1. Sender Behavior . . . . . . . . . . . . . . . . . . . . . 10 5. Extended TWAMP Test .............................................9
4.1.1. Packet Timings . . . . . . . . . . . . . . . . . . . . 10 5.1. Sender Behavior ............................................9
4.1.2. Reflect Octets: Packet Formats and Contents . . . . . 10 5.1.1. Packet Timings ......................................9
4.1.3. Reflect Octets: Interaction with Padding Truncation . 12 5.1.2. Reflect Octets: Packet Formats and Contents .........9
4.1.4. Symmetrical Size: Session-Sender Packet Format . . . . 13 5.1.3. Reflect Octets: Interaction with Padding
4.1.5. Symmetrical Size AND Reflect Octets: Truncation .........................................11
Session-Sender Packet Format . . . . . . . . . . . . . 14 5.1.4. Symmetrical Size: Session-Sender Packet Format .....13
4.2. Reflector Behavior . . . . . . . . . . . . . . . . . . . . 15 5.1.5. Symmetrical Size AND Reflect Octets:
4.2.1. Reflect Octets: Session-Reflector Packet Format Session-Sender Packet ..............................14
and Contents . . . . . . . . . . . . . . . . . . . . . 16 5.2. Reflector Behavior ........................................14
4.2.2. Symmetrical Size: Session-Reflector Packet Format . . 17 5.2.1. Reflect Octets: Session-Reflector Packet
4.2.3. Symmetrical Size AND Reflect Octets: Format and Contents ................................15
Session-Sender Packet Format . . . . . . . . . . . . . 17 5.2.2. Symmetrical Size: Session-Reflector Packet Format ..16
5. Security Considerations . . . . . . . . . . . . . . . . . . . 17 5.2.3. Symmetrical Size AND Reflect Octets:
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 Session-Sender Packet Format .......................16
6.1. Registry Specification . . . . . . . . . . . . . . . . . . 18 6. Security Considerations ........................................17
6.2. Registry Contents . . . . . . . . . . . . . . . . . . . . 18 7. IANA Considerations ............................................17
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 7.1. Registry Specification ....................................17
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 7.2. Registry Contents .........................................17
8.1. Normative References . . . . . . . . . . . . . . . . . . . 19 8. Acknowledgements ...............................................17
8.2. Informative References . . . . . . . . . . . . . . . . . . 19 9. Normative References ...........................................18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
TWAMP - the Two-Way Active Measurement Protocol [RFC5357] is an The Two-Way Active Measurement Protocol (TWAMP) [RFC5357] is an
extension of the One-way Active Measurement Protocol, OWAMP extension of the One-way Active Measurement Protocol (OWAMP)
[RFC4656]. The TWAMP specification gathered wide review as it [RFC4656]. The TWAMP specification gathered wide review as it
approached completion, and the by-products were several approached completion, and the by-products were several
recommendations for new features in TWAMP. recommendations for new features in TWAMP.
This memo describes two closely-related features for TWAMP. This memo describes two closely related features for TWAMP.
One is the OPTIONAL capability for the responder host to return a One is the OPTIONAL capability for the responder host to return a
limited number of unassigned (padding) octets to the Control-Client limited number of unassigned (padding) octets to the Control-Client
or Session-Sender entities in both the TWAMP-Control and TWAMP-Test or Session-Sender entities in both the TWAMP-Control and TWAMP-Test
protocols. With this capability, the Control-Client or Session- protocols. With this capability, the Control-Client or Session-
Sender can embed octets of information it deems useful and have the Sender can embed octets of information it deems useful and have the
assurance that the corresponding reply/test packet will contain that assurance that the corresponding reply/test packet will contain that
information when it is reflected and returned (by the Server or information when it is reflected and returned (by the Server or
Session-Reflector). Session-Reflector).
The memo also adds an OPTIONAL capability to assure that reflected The memo also adds an OPTIONAL capability to ensure that reflected
test packets are the same size in both directions of transmission. test packets are the same size in both directions of transmission.
This is accomplished by specifying a new TWAMP-Test Session-Sender This is accomplished by specifying a new TWAMP-Test Session-Sender
packet format. Although TWAMP [RFC5357] recommends padding packet format. Although TWAMP [RFC5357] recommends padding
truncation to achieve symmetrical sizes (to compensate for the truncation to achieve symmetrical sizes (to compensate for the
Session-Reflector's larger test packet header), it's not guaranteed Session-Reflector's larger test packet header), it's not guaranteed
that the Session-Reflector will truncate the padding, and it's not that the Session-Reflector will truncate the padding, and it's not
possible if there's insufficient padding. possible if there's insufficient padding.
This memo is an update to the TWAMP core protocol specified in This memo is an update to the TWAMP core protocol specified in
[RFC5357]. Measurement systems are not required to implement the [RFC5357]. Measurement systems are not required to implement the
features described in this memo to claim compliance with [RFC5357]. features described in this memo to claim compliance with [RFC5357].
Throughout this memo, the bits marked MBZ (Must Be Zero) MUST be set Throughout this memo, the bits marked MBZ (Must Be Zero) MUST be set
to zero by senders and MUST be ignored by receivers. Also, the HMAC to zero by senders and MUST be ignored by receivers. Also, the HMAC
(Hashed Message Authentication Code) MUST be calculated as defined in (Hashed Message Authentication Code) MUST be calculated as defined in
Section 3.2 of [RFC4656]. Section 3.2 of [RFC4656].
2. Purpose and Scope 2. Requirements Language
The purpose of this memo is to define two OPTIONAL closely-related The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. Purpose and Scope
The purpose of this memo is to define two OPTIONAL closely related
features for TWAMP [RFC5357]. The features enhance the TWAMP host's features for TWAMP [RFC5357]. The features enhance the TWAMP host's
capabilities to perform a simple operation on control and test capabilities to perform a simple operation on control and test
packets: the reflection of octets or padding, and the capability to packets: the reflection of octets or padding, and the capability to
ensure symmetrical size TWAMP-Test packets. Motivations include ensure symmetrical size TWAMP-Test packets. Motivations include
permitting the controller host to tag packets with an index for permitting the controller host to tag packets with an index for
simplified identification, and/or assert that the same size test simplified identification, and/or assert that the same size test
packets will be used in each direction. packets will be used in each direction.
The scope of the memo is limited to specifications of the following The scope of the memo is limited to specifications of the following
features: features:
skipping to change at page 5, line 19 skipping to change at page 4, line 30
reflect specific octets back to the Client/Session-Sender, and a reflect specific octets back to the Client/Session-Sender, and a
similar service provided by the Client and Session-Sender. similar service provided by the Client and Session-Sender.
o Symmetrical Size: the capability to ensure that TWAMP-Test o Symmetrical Size: the capability to ensure that TWAMP-Test
protocol uses the same packet size in both directions through protocol uses the same packet size in both directions through
support of a new TWAMP-Test Session-Sender test packet format in support of a new TWAMP-Test Session-Sender test packet format in
both the Session-Sender and the Session-Reflector. Only the both the Session-Sender and the Session-Reflector. Only the
Session-Sender test packet format is new. Session-Sender test packet format is new.
This memo extends the modes of operation through assignment of two This memo extends the modes of operation through assignment of two
new values in the Modes Field (see section 3.1 of[RFC4656] for the new values in the Modes field (see Section 3.1 of [RFC4656] for the
format of the Server Greeting message), while retaining backward format of the Server Greeting message), while retaining backward
compatibility with the core TWAMP [RFC5357] implementations. The two compatibility with the core TWAMP [RFC5357] implementations. The two
new values correspond to the two features defined in this memo. new values correspond to the two features defined in this memo.
When the Server and Control-Client have agreed to use the Reflect When the Server and Control-Client have agreed to use the Reflect
Octets mode during control connection setup, then the Control-Client, Octets mode during control connection setup, then the Control-Client,
the Server, the Session-Sender, and the Session-Reflector MUST all the Server, the Session-Sender, and the Session-Reflector MUST all
conform to the requirements of that mode, as identified below. conform to the requirements of that mode, as identified below.
When the Server and Control-Client have agreed to use the Symmetrical When the Server and Control-Client have agreed to use the Symmetrical
Size mode during control connection setup, then the Control-Client, Size mode during control connection setup, then the Control-Client,
the Server, the Session-Sender, and the Session-Reflector MUST all the Server, the Session-Sender, and the Session-Reflector MUST all
conform to the requirements of that mode, as identified below. conform to the requirements of that mode, as identified below.
3. TWAMP Control Extensions 4. TWAMP Control Extensions
TWAMP-Control protocol [RFC5357] uses the Modes Field to identify and TWAMP-Control protocol [RFC5357] uses the Modes field to identify and
select specific communication capabilities, and this field is a select specific communication capabilities, and this field is a
recognized extension mechanism. The following sections describe two recognized extension mechanism. The following sections describe two
such extensions. such extensions.
3.1. Connection Setup with New Features 4.1. Connection Setup with New Features
TWAMP connection establishment follows the procedure defined in TWAMP connection establishment follows the procedure defined in
section 3.1 of [RFC4656] and section 3.1 of [RFC5357]. The new Section 3.1 of [RFC4656] and Section 3.1 of [RFC5357]. The new
features require two new bit positions (and values) to identify the features require two new bit positions (and values) to identify the
ability of the Server/Session-Reflector to reflect specific octets ability of the Server/Session-Reflector to reflect specific octets
back to the Control-Client/Session-Sender, and to support the new back to the Control-Client/Session-Sender, and to support the new
Session-Sender packet format in TWAMP-Test Protocol. See the IANA Session-Sender packet format in the TWAMP-Test protocol. See the
section for details on the assigned values and bit positions. IANA section for details on the assigned values and bit positions.
The Server sets one or both of the new bit positions in the Modes The Server sets one or both of the new bit positions in the Modes
Field of the Server Greeting message to indicate its capabilities and field of the Server Greeting message to indicate its capabilities and
willingness to operate in either of these modes (or both) if desired. willingness to operate in either of these modes (or both) if desired.
If the Control-Client intends to operate all test sessions invoked If the Control-Client intends to operate all test sessions invoked
with this control connection using one or both of the new modes, it with this control connection using one or both of the new modes, it
MUST set the Mode Field bit corresponding to each function in the MUST set the Mode field bit corresponding to each function in the
Setup Response message. With this and other extensions, the Control- Setup Response message. With this and other extensions, the Control-
Client MAY set multiple Mode Field bits in the Setup Response Client MAY set multiple Mode field bits in the Setup Response
message. message.
3.2. Reflect Octets: Request-TW-Session Packet Format 4.2. Reflect Octets: Request-TW-Session Packet Format
The bits designated for the Reflect Octets feature in the Request-TW- The bits designated for the Reflect Octets feature in the Request-TW-
Session command are as shown in the packet format below. Session command are as shown in the packet format below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5 | MBZ | IPVN | Conf-Sender | Conf-Receiver | | 5 | MBZ | IPVN | Conf-Sender | Conf-Receiver |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Schedule Slots | | Number of Schedule Slots |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. ... Many fields (66 octets) not shown ... . . ... Many fields (66 octets) not shown ... .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Padding Length (4 octets) | | Padding Length (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Start Time, (8 octets) | | Start Time (8 octets) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timeout, (8 octets) | | Timeout (8 octets) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type-P Descriptor | | Type-P Descriptor |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Octets to be reflected | Length of padding to reflect | | Octets to be reflected | Length of padding to reflect |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (4 octets) | | MBZ (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| HMAC (16 octets) | | HMAC (16 octets) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
It is important to note that the "Padding Length" Field continues to It is important to note that the Padding Length field continues to
specify the number of padding octets that the Session-Sender will specify the number of padding octets that the Session-Sender will
append to ALL TWAMP-Test packets associated with this test session. append to ALL TWAMP-Test packets associated with this test session.
See below for considerations on the minimum length of the padding See below for considerations on the minimum length of the padding
octets, following the definitions of the two new fields that follow octets following the definitions of the two new fields that follow
the Type-P Descriptor. the Type-P Descriptor.
Note that the number of padding octets appended to the Session- Note that the number of padding octets appended to the Session-
Reflector's test packet depends on support for the truncation process Reflector's test packet depends on support for the truncation process
that TWAMP section 4.2.1 [RFC5357] recommends. that TWAMP recommends, see Section 4.2.1 of [RFC5357].
The "Octets to be reflected" Field SHALL be 2 octets long, as shown The Octets to be reflected field SHALL be 2 octets long, as shown,
and contains the octets that the Server MUST reflect in the Accept and contain the octets that the Server MUST reflect in the Accept
Session message as specified below. Session message as specified below.
The "Length of padding to reflect" Field SHALL be 2 octets long, and The Length of padding to reflect field SHALL be 2 octets long and
contain an unsigned binary value in units of octets. This field contain an unsigned binary value in units of octets. This field
communicates the length of the padding in the TWAMP-Test Packet that communicates the length of the padding in the TWAMP-Test Packet that
the Session-Sender expects to be reflected, and the length of octets the Session-Sender expects to be reflected and the length of octets
that the Session-Reflector SHALL return in its TWAMP-Test packet that the Session-Reflector SHALL return in its TWAMP-Test packet
format (see section 4.2). By including this length field in the format (see Section 5.2). By including this length field in the
Request-TW-Session message, a Server is able to determine if it can Request-TW-Session message, a Server is able to determine if it can
comply with a specific request to reflect padding in the TWAMP-Test comply with a specific request to reflect padding in the TWAMP-Test
packets, and to arrange for the Session-Reflector processing in packets and to arrange for the Session-Reflector processing in
advance. advance.
The "Padding Length" SHOULD be >= 27 octets when specifying a test The Padding Length SHOULD be >= 27 octets when specifying a test
session using the Unauthenticated TWAMP-Test mode, to allow for the session using the Unauthenticated TWAMP-Test mode to allow for the
truncation process that TWAMP section 4.2.1 [RFC5357] recommends. truncation process that TWAMP recommends, see Section 4.2.1 of
[RFC5357].
The "Padding Length" SHOULD be >= 56 octets when specifying a test The Padding Length SHOULD be >= 56 octets when specifying a test
session using the Authenticated or Encrypted TWAMP-Test modes, to session using the Authenticated or Encrypted TWAMP-Test modes to
allow for the truncation process that TWAMP section 4.2.1 [RFC5357] allow for the truncation process that TWAMP recommends, see Section
recommends. 4.2.1 of [RFC5357].
The "Padding Length" SHALL be > the "Length of padding to reflect" The Padding Length SHALL be > the Length of padding to reflect when
when specifying a test session using the OPTIONAL Reflect Octets specifying a test session using the OPTIONAL Reflect Octets mode.
mode.
In Unauthenticated TWAMP-Test mode, the "Padding Length" SHALL be >= In Unauthenticated TWAMP-Test mode, the Padding Length SHALL be >= 27
27 + "Length of padding to reflect" octets when specifying a test + Length of padding to reflect octets when specifying a test session
session using both the OPTIONAL Reflect Octets mode and the using both the OPTIONAL Reflect Octets mode and the truncation
truncation process that TWAMP section 4.2.1 [RFC5357] recommends. process that TWAMP recommends, see Section 4.2.1 of [RFC5357].
In Authenticated or Encrypted TWAMP-Test modes, the "Padding Length" In Authenticated or Encrypted TWAMP-Test modes, the Padding Length
SHALL be >= 56 + "Length of padding to reflect" octets when SHALL be >= 56 + Length of padding to reflect octets when specifying
specifying a test session using both the OPTIONAL Reflect Octets mode a test session using both the OPTIONAL Reflect Octets mode and the
and the truncation process that TWAMP section 4.2.1 [RFC5357] truncation process that TWAMP recommends, see Section 4.2.1 of
recommends. [RFC5357].
3.3. Reflect Octets: Accept Session Packet Format 4.3. Reflect Octets: Accept Session Packet Format
The bits designated for the Reflect Padding feature in the Accept The bits designated for the Reflect Padding feature in the Accept
Session command are as shown in the packet format below. Session command are as shown in the packet format below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Accept | MBZ | Port | | Accept | MBZ | Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | | |
skipping to change at page 9, line 26 skipping to change at page 8, line 26
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) | | MBZ (8 octets) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| HMAC (16 octets) | | HMAC (16 octets) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The "Reflected octets" field SHALL contain the octets from the The Reflected octets field SHALL contain the octets from the Request-
Request-TW-Session "Octets to be reflected" Field, and be 2 octets TW-Session Octets to be reflected field and be 2 octets long, as
long, as shown. shown.
The "Server octets" field SHALL contain information that the Server The Server octets field SHALL contain information that the Server
intends to be returned in the TWAMP-Test packet padding to-be- intends to be returned in the TWAMP-Test Packet Padding (to be
reflected Field, OR SHALL be zero, and be 2 octets long, as shown. reflected) field, OR SHALL be zero, and be 2 octets long, as shown.
Although the Server determines the SID, this field is very long (16 Although the Server determines the SID, this field is very long (16
octets) and does not normally appear in TWAMP-Test packets. The octets) and does not normally appear in TWAMP-Test packets. The
following items MUST be part of compliant implementations using the following items MUST be part of compliant implementations using the
Reflect Octets feature: Reflect Octets feature:
o When a Server does not require octets to be returned in TWAMP-Test o When a Server does not require octets to be returned in TWAMP-Test
packets, it MUST send all zeros in the Server octets field packets, it MUST send all zeros in the Server octets field.
o When a Server intends octets to be returned in TWAMP-Test packets, o When a Server intends octets to be returned in TWAMP-Test packets,
it MUST send a non-zero value in the Server octets field, and the it MUST send a non-zero value in the Server octets field, and the
TWAMP-Test Sender MUST include those octets at the beginning of TWAMP-Test Sender MUST include those octets at the beginning of
the "Packet Padding (to be reflected)" field the Packet Padding (to be reflected) field.
o Section 4.1.2 defines how Server octets MUST be included in the o Section 4.1.2 defines how Server octets MUST be included in the
TWAMP-Test packet padding when this service is desired by the TWAMP-Test packet padding when this service is desired by the
Server (indicated in the second of two figures in the section) Server (indicated in the second of two figures in this section).
When performing the truncation process that TWAMP section 4.2.1 When performing the truncation process that TWAMP recommends, see
[RFC5357] recommends, if calculations on the Padding lengths reveal Section 4.2.1 of [RFC5357], if calculations on the Padding lengths
that there are insufficient octets supplied to produce equal-length reveal that there are insufficient octets supplied to produce equal-
Session-Sender and Session-Reflector test packets, then the Accept length Session-Sender and Session-Reflector test packets, then the
Field MUST be set to 3 to indicate that some aspect of the request is Accept field MUST be set to 3 to indicate that some aspect of the
not supported. request is not supported.
3.4. Additional considerations 4.4. Additional Considerations
The value of the Modes Field sent by the Server in the Server The value of the Modes field sent by the Server in the Server
Greeting message is the bit-wise OR of the mode values that it is Greeting message is the bit-wise OR of the mode values that it is
willing to support during this session. willing to support during this session.
With the publication of this memo as an RFC, the last 7 bit positions With the publication of this memo as an RFC, the last 7 bit positions
of the Modes 32-bit Field are used. A Control-Client conforming to of the Modes 32-bit field are used. A Control-Client conforming to
this extension of [RFC5357] MAY ignore the values in the higher bits this extension of [RFC5357] MAY ignore the values in the higher bits
of the Modes Field, or it MAY support other features that are of the Modes field, or it MAY support other features that are
communicated in those bit positions. The other bits are available communicated in those bit positions. The other bits are available
for future protocol extensions. for future protocol extensions.
4. Extended TWAMP Test 5. Extended TWAMP Test
The TWAMP test protocol is similar to the OWAMP [RFC4656] test The TWAMP-Test protocol is similar to the OWAMP [RFC4656] test
protocol with the exception that the Session-Reflector transmits test protocol with the exception that the Session-Reflector transmits test
packets to the Session-Sender in response to each test packet it packets to the Session-Sender in response to each test packet it
receives. TWAMP section 4[RFC5357] defines two additional test receives. TWAMP, see Section 4 of [RFC5357], defines two additional
packet formats for packets transmitted by the Session-Reflector. The test packet formats for packets transmitted by the Session-Reflector.
appropriate format depends on the security mode chosen. The new The appropriate format depends on the security mode chosen. The new
modes specified here utilize some of the padding octets within each modes specified here utilize some of the padding octets within each
test packet format, or require truncation of those octets depending test packet format or require truncation of those octets depending on
on the security mode in use. the security mode in use.
4.1. Sender Behavior 5.1. Sender Behavior
This section describes extensions to the behavior of the TWAMP This section describes extensions to the behavior of the TWAMP
Session-Sender. Session-Sender.
4.1.1. Packet Timings 5.1.1. Packet Timings
The Send Schedule is not utilized in TWAMP, and this is unchanged in The Send Schedule is not utilized in TWAMP, and this is unchanged in
this memo. this memo.
4.1.2. Reflect Octets: Packet Formats and Contents 5.1.2. Reflect Octets: Packet Formats and Contents
The Session-Sender packet format and content follow the same The Session-Sender packet format and content follow the same
procedure and guidelines as defined in section 4.1.2 of [RFC4656] (as procedure and guidelines as defined in Section 4.1.2 of [RFC4656] (as
indicated in section 4.1.2 of TWAMP [RFC5357]). indicated in Section 4.1.2 of [RFC5357]).
The Reflect octets mode re-designates the original TWAMP-Test Packet The Reflect Octets mode re-designates the original TWAMP-Test Packet
Padding Field (see section 4.1.2 of [RFC4656]), as shown below for Padding field (see Section 4.1.2 of [RFC4656]), as shown below for
unauthenticated mode: Unauthenticated mode:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp | | Timestamp |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | | | Error Estimate | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
| Packet Padding (to be reflected) | | Packet Padding (to be reflected) |
. (length in octets specified in command) . . (length in octets specified in command) .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. Additional Packet Padding . . Additional Packet Padding .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The "Packet Padding (to be reflected)" Field SHALL correspond to the The Packet Padding (to be reflected) field SHALL correspond to the
length of octets specified in the Request-TW-Session "Length of length of octets specified in the Request-TW-Session Length of
padding to reflect" Field to this test session. These are the octets padding to reflect field to this test session. These are the octets
that the Session-Sender expects will be returned by the Session- that the Session-Sender expects will be returned by the Session-
Reflector. Reflector.
The length of the "Additional Packet Padding" Field is the difference The length of the Additional Packet Padding field is the difference
between two fields in the Request-TW-Session command, as follows: between two fields in the Request-TW-Session command, as follows:
"Additional Packet Padding", in octets = Additional Packet Padding, in octets =
"Padding Length" - "Length of padding to reflect" Padding Length - Length of padding to reflect
When a Server intends octets to be returned in TWAMP-Test packets, it When a Server intends octets to be returned in TWAMP-Test packets, it
MUST send a non-zero value in the Server octets field, and the TWAMP- MUST send a non-zero value in the Server octets field, and the TWAMP-
Test Session-Sender MUST include those octets in the first 2 octets Test Session-Sender MUST include those octets in the first 2 octets
of the "Packet Padding (to be reflected)" Field as shown below: of the Packet Padding (to be reflected) field as shown below:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Server octets | | Server octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Remaining Packet Padding (to be reflected) | | Remaining Packet Padding (to be reflected) |
. (total length in octets specified in command) . . (total length in octets specified in command) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The "Server octets" field contains the same information that the The Server octets field contains the same information that the Server
Server returned to the Control-Client in the Accept-Session message returned to the Control-Client in the Accept-Session message
corresponding to this specific test session (see section 3.3). At corresponding to this specific test session (see Section 4.3). At
the Session-Reflector, these octets MUST be reflected the same as the the Session-Reflector, these octets MUST be reflected the same as the
rest of the "Packet Padding (to be reflected)" field. rest of the Packet Padding (to be reflected) field.
Note that it is permissible for the Session-Sender to insert the same Note that it is permissible for the Session-Sender to insert the same
octets used in the "Octets to be reflected" field of the Request-TW- octets used in the Octets to be reflected field of the Request-TW-
Session command elsewhere in the "Packet Padding (to be reflected)" Session command elsewhere in the Packet Padding (to be reflected)
field. field.
4.1.3. Reflect Octets: Interaction with Padding Truncation 5.1.3. Reflect Octets: Interaction with Padding Truncation
When the Reflect Octets mode is selected, and the performing When the Reflect Octets mode is selected, and performing the
truncation process that TWAMP section 4.2.1 [RFC5357] recommends, the truncation process that TWAMP recommends, see Section 4.2.1 of
Session-Sender MUST anticipate a minimum padding required to achieve [RFC5357], the Session-Sender MUST anticipate a minimum padding
equal size test packets in both directions. The amount of padding required to achieve equal-size test packets in both directions. The
needed to achieve symmetrical packet size depends on both the amount of padding needed to achieve symmetrical packet size depends
security mode (Unauthenticated/Authenticated/Encrypted) and whether on both the security mode (Unauthenticated/Authenticated/Encrypted)
the Reflect Octets mode is selected simultaneously. and whether the Reflect Octets mode is selected simultaneously.
When using the truncation process in TWAMP section 4.2.1 [RFC5357] When using the truncation process in TWAMP alone, see Section 4.2.1
alone, the Session-Sender MUST append sufficient Packet Padding of [RFC5357], the Session-Sender MUST append sufficient Packet
octets to allow the same IP packet payload lengths to be used in each Padding octets to allow the same IP packet payload lengths to be used
direction of transmission (this is usually desirable). To compensate in each direction of transmission (this is usually desirable). To
for the Session-Reflector's larger test packet format, the Session- compensate for the Session-Reflector's larger test packet format, the
Sender MUST append at least 27 octets of padding in Unauthenticated Session-Sender MUST append at least 27 octets of padding in
mode, and at least 56 octets in Authenticated and Encrypted modes. Unauthenticated mode, and at least 56 octets in Authenticated and
The sizes of TWAMP Test protocol packets and the resulting truncated Encrypted modes. The sizes of TWAMP-Test protocol packets and the
padding to achieve equal packet sizes in both directions are shown in resulting truncated padding to achieve equal packet sizes in both
the table below: directions are shown in the table below:
+-------------------+----------------------+---------------------+ +-------------------+----------------------+---------------------+
| Octets in: | Unauthenticated Mode | Auth/Encrypted Mode | | Octets in: | Unauthenticated Mode | Auth/Encrypted Mode |
+-------------------+----------------------+---------------------+ +-------------------+----------------------+---------------------+
| Reflector Header | 41 | 104 | | Reflector Header | 41 | 104 |
| Sender Header | 14 | 48 | | Sender Header | 14 | 48 |
| Truncated Padding | 27 | 56 | | Truncated Padding | 27 | 56 |
+-------------------+----------------------+---------------------+ +-------------------+----------------------+---------------------+
TWAMP-Test Padding Truncation TWAMP-Test Padding Truncation
When using the Reflect Octets mode simultaneously with the truncation When using the Reflect Octets mode simultaneously with the truncation
process that TWAMP recommends in section 4.2.1 [RFC5357], the process that TWAMP recommends in Section 4.2.1 of [RFC5357], the
Session-Sender MUST append at least 27 octets of padding plus the Session-Sender MUST append at least 27 octets of padding plus the
"Length of the padding to reflect" octets when operating in Length of the padding to reflect octets when operating in
Unauthenticated mode. The Session-Sender MUST append at least 56 Unauthenticated mode. The Session-Sender MUST append at least 56
octets of padding plus the "Length of the padding to reflect" octets octets of padding plus the Length of the padding to reflect octets
when operating in Authenticated and Encrypted modes. when operating in Authenticated and Encrypted modes.
4.1.4. Symmetrical Size: Session-Sender Packet Format 5.1.4. Symmetrical Size: Session-Sender Packet Format
When the Symmetrical Size mode is selected, the Session-Sender SHALL When the Symmetrical Size mode is selected, the Session-Sender SHALL
use the following TWAMP-Test Packet Format in Unauthenticated mode: use the following TWAMP-Test Packet Format in Unauthenticated mode:
Unauthenticated Mode Unauthenticated Mode
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp | | Timestamp |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | | | Error Estimate | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
skipping to change at page 14, line 33 skipping to change at page 14, line 5
| | | | | |
+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+ +
. . . .
. Packet Padding . . Packet Padding .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This feature REQUIRES only a new Session-Sender test packet format, This feature REQUIRES only a new Session-Sender test packet format,
the Session-Reflector test packet format is unchanged. the Session-Reflector test packet format is unchanged.
4.1.5. Symmetrical Size AND Reflect Octets: Session-Sender Packet 5.1.5. Symmetrical Size AND Reflect Octets: Session-Sender Packet
Format Format
When both the Symmetrical Size mode and the Reflect Octets mode are When both the Symmetrical Size mode and the Reflect Octets mode are
selected, the Session-Sender SHALL use the following TWAMP-Test selected, the Session-Sender SHALL use the following TWAMP-Test
Packet Format in Unauthenticated mode: Packet Format in Unauthenticated mode:
Unauthenticated Mode Unauthenticated Mode
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp | | Timestamp |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | | | Error Estimate | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
skipping to change at page 15, line 37 skipping to change at page 14, line 45
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. Additional Packet Padding . . Additional Packet Padding .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In this combined mode, the Packet Padding to be reflected follows the In this combined mode, the Packet Padding to be reflected follows the
27 MBZ octets. In Authenticated or Encrypted modes, the Packet 27 MBZ octets. In Authenticated or Encrypted modes, the Packet
Padding to be reflected follows the 56 MBZ octets. Padding to be reflected follows the 56 MBZ octets.
4.2. Reflector Behavior 5.2. Reflector Behavior
The TWAMP Reflector follows the procedures and guidelines in section The TWAMP Reflector follows the procedures and guidelines in Section
4.2 of [RFC5357], with the following additional functions: 4.2 of [RFC5357], with the following additional functions:
o Reflect Octets mode: Designated octets in the "Packet Padding (to o Reflect Octets mode: Designated octets in the Packet Padding (to
be reflected)" field of the Session-Sender's test packet MUST be be reflected) field of the Session-Sender's test packet MUST be
included in the Session-Reflector's test packet. included in the Session-Reflector's test packet.
o Symmetrical Size mode: The Session-Reflector MUST operate using o Symmetrical Size mode: The Session-Reflector MUST operate using
the Session_Reflector Packet Format defined in section 4.1.4, the Session_Reflector Packet Format defined in Section 5.1.4,
where the Padding Octets are separated from the information where the Padding Octets are separated from the information
fields. fields.
4.2.1. Reflect Octets: Session-Reflector Packet Format and Contents 5.2.1. Reflect Octets: Session-Reflector Packet Format and Contents
The Reflect Padding feature re-designates the packet padding field, The Reflect Padding feature re-designates the Packet Padding field,
as shown below. When the Reflect Octets mode is selected, the as shown below. When the Reflect Octets mode is selected, the
Session-Sender SHALL use the following TWAMP-Test Packet Format in Session-Sender SHALL use the following TWAMP-Test Packet Format in
Unauthenticated mode: Unauthenticated mode:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp | | Timestamp |
skipping to change at page 16, line 42 skipping to change at page 15, line 47
| Sender TTL | Packet Padding (from Session-Sender) | | Sender TTL | Packet Padding (from Session-Sender) |
+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+ +
. . . .
+ +-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+
| Packet Padding (from Session-Sender) | | | Packet Padding (from Session-Sender) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
| | | |
. Additional Packet Padding . . Additional Packet Padding .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The "Packet Padding (from Session-Sender)" field MUST be the same
octets as the "Packet Padding (to be reflected)" field in the
Session-Sender's test packet, and therefore MUST conform to the
length specified in the Request-TW-Session message.
When the Server has returned a non-zero value in the "Server octets" The Packet Padding (from Session-Sender) field MUST be the same
field of the Accept Session message (as described in section 3.3), octets as the Packet Padding (to be reflected) field in the Session-
Sender's test packet, and therefore MUST conform to the length
specified in the Request-TW-Session message.
When the Server has returned a non-zero value in the Server octets
field of the Accept Session message (as described in Section 4.3),
then the Session-Reflector SHALL reflect these octets the same as the then the Session-Reflector SHALL reflect these octets the same as the
rest of the "Packet Padding (to be reflected)" Field. rest of the Packet Padding (to be reflected) field.
Section 4.2.1 of [RFC5357] recommends a padding truncation process Section 4.2.1 of [RFC5357] recommends a padding truncation process
for use in TWAMP. When using that process in conjunction with the for use in TWAMP. When using that process in conjunction with the
Reflect octets mode, the Session-Reflector MUST reflect the Reflect Octets mode, the Session-Reflector MUST reflect the
designated octets from the Session-Sender's test packet in the designated octets from the Session-Sender's test packet in the Packet
"Packet Padding (from Session-Sender)" Field, and MAY re-use Padding (from Session-Sender) field, and MAY re-use additional Packet
additional Packet Padding from the Session-Sender. The Session- Padding from the Session-Sender. The Session-Reflector MUST truncate
Reflector MUST truncate the padding such that the highest number the padding such that the highest number octets are discarded, and
octets are discarded, and the test packet length equals the Session- the test packet length equals the Session-Sender's packet length.
Sender's packet length. When using the recommended truncation When using the recommended truncation process, the Session-Reflector
process, the Session-Reflector MUST truncate exactly 27 octets of MUST truncate exactly 27 octets of padding in Unauthenticated mode,
padding in Unauthenticated mode, and exactly 56 octets in and exactly 56 octets in Authenticated and Encrypted modes.
Authenticated and Encrypted modes.
In any case, the Session-Reflector MAY re-use the Sender's Packet In any case, the Session-Reflector MAY re-use the Sender's Packet
Padding (since the requirements for padding generation are the same Padding (since the requirements for padding generation are the same
for each). for each).
4.2.2. Symmetrical Size: Session-Reflector Packet Format 5.2.2. Symmetrical Size: Session-Reflector Packet Format
When Symmetrical Size mode is selected, the Session-Reflector packet When Symmetrical Size mode is selected, the Session-Reflector packet
formats for unauthenticated and authenticated/encrypted modes are formats for Unauthenticated and Authenticated/Encrypted modes are
identical to the core TWAMP specification, section 4.2.1 of identical to the core TWAMP specification, see Section 4.2.1 of
[RFC5357]. Thus, the Session-Reflector test packet format is [RFC5357]. Thus, the Session-Reflector test packet format is
unchanged. unchanged.
The Session-Reflector MUST construct its test packet using the The Session-Reflector MUST construct its test packet using the
information in the Session-Sender's test packet. The length of the information in the Session-Sender's test packet. The length of the
Session-Reflector's test packet SHALL equal the length of the Session-Reflector's test packet SHALL equal the length of the
Session-Sender's test packet. Session-Sender's test packet.
4.2.3. Symmetrical Size AND Reflect Octets: Session-Sender Packet 5.2.3. Symmetrical Size AND Reflect Octets: Session-Sender Packet
Format Format
When both the Symmetrical Size mode and the Reflect Octets mode are When both the Symmetrical Size mode and the Reflect Octets mode are
selected, the Session-Reflector MUST operate using the Session- selected, the Session-Reflector MUST operate using the Session-Sender
Reflector Packet Format defined in section 4.1.5, where the Padding Packet Format defined in Section 5.1.5, where the Padding Octets are
Octets are separated from the information fields, and the Padding to separated from the information fields, and the Packet Padding (to be
be Reflected field precedes the Additional Padding. reflected) field precedes the Additional Padding.
The Session-Reflector SHALL use the same TWAMP-Test Packet Format as The Session-Reflector SHALL use the same TWAMP-Test Packet Format as
specified in section 4.2.1 above. specified in Section 5.2.1, above.
5. Security Considerations 6. Security Considerations
These extended modes of operation do not appear to permit any new These extended modes of operation do not appear to permit any new
attacks on hosts communicating with core TWAMP [RFC5357]. attacks on hosts communicating with core TWAMP [RFC5357].
The security considerations that apply to any active measurement of The security considerations that apply to any active measurement of
live networks are relevant here as well. See [RFC4656] and live networks are relevant here as well. See [RFC4656] and
[RFC5357]. [RFC5357].
6. IANA Considerations 7. IANA Considerations
This memo adds two modes to the IANA registry for the TWAMP Modes This memo adds two modes to the IANA registry for the TWAMP Modes
Field, and describes behavior when the new modes are used. This field, and describes behavior when the new modes are used. This
field is a recognized extension mechanism for TWAMP. field is a recognized extension mechanism for TWAMP.
6.1. Registry Specification 7.1. Registry Specification
IANA has created a TWAMP-Modes registry (as requested in [RFC5618]). IANA has created a TWAMP-Modes registry (as requested in [RFC5618]).
TWAMP-Modes are specified in TWAMP Server Greeting messages and TWAMP-Modes are specified in TWAMP Server Greeting messages and Setup
Set-up Response messages, as described in section 3.1 of [RFC5357], Response messages, as described in Section 3.1 of [RFC5357],
consistent with section 3.1 of [RFC4656], and extended by this memo. consistent with Section 3.1 of [RFC4656], and extended by this memo.
Modes are indicated by setting bits in the 32-bit Modes field that Modes are indicated by setting bits in the 32-bit Modes field that
correspond to values in the Modes registry. For the TWAMP-Modes correspond to values in the Modes registry. For the TWAMP-Modes
registry, we expect that new features will be assigned increasing registry, we expect that new features will be assigned increasing
registry values that correspond to single bit positions, unless there registry values that correspond to single bit positions, unless there
is a good reason to do otherwise (more complex encoding than single is a good reason to do otherwise (more complex encoding than single-
bit positions may be used in the future, to access the 2^32 value bit positions may be used in the future to access the 2^32 value
space). space).
6.2. Registry Contents 7.2. Registry Contents
TWAMP Modes Registry is recommended to be augmented as follows: The TWAMP-Modes registry has been augmented as follows:
Value Description Semantics Definition Value Description Semantics Definition
-------------------------------------------------------- --------------------------------------------------------
xxx Reflect Octets this memo, section 3.1 32 Reflect Octets this memo, Section 3.1
Capability new bit position (X) Capability new bit position (5)
yyy Symmetrical Size this memo, section 3.1 64 Symmetrical Size this memo, Section 3.1
Sender Test Packet Format new bit position (Y) Sender Test Packet Format new bit position (6)
>>>IANA: change xxx, yyy, X, Y, and RFC???? to the assigned values
The suggested values are
X=5, xxx=32
Y=6, yyy=64 <<<<
7. Acknowledgements 8. Acknowledgements
The authors thank Steve Baillargeon, Walt Steverson, and Stina Ross The authors thank Steve Baillargeon, Walt Steverson, and Stina Ross
for helpful review and comments. for helpful review and comments.
8. References 9. Normative References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] 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.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, September 2006. (OWAMP)", RFC 4656, September 2006.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, October 2008. RFC 5357, October 2008.
[RFC5618] Morton, A. and K. Hedayat, "Mixed Security Mode for the [RFC5618] Morton, A. and K. Hedayat, "Mixed Security Mode for the
Two-Way Active Measurement Protocol (TWAMP)", RFC 5618, Two-Way Active Measurement Protocol (TWAMP)", RFC 5618,
August 2009. August 2009.
8.2. Informative References
Authors' Addresses Authors' Addresses
Al Morton Al Morton
AT&T Labs AT&T Labs
200 Laurel Avenue South 200 Laurel Avenue South
Middletown,, NJ 07748 Middletown, NJ 07748
USA USA
Phone: +1 732 420 1571 Phone: +1 732 420 1571
Fax: +1 732 368 1192 Fax: +1 732 368 1192
Email: acmorton@att.com EMail: acmorton@att.com
URI: http://home.comcast.net/~acmacm/ URI: http://home.comcast.net/~acmacm/
Len Ciavattone Len Ciavattone
AT&T Labs AT&T Labs
200 Laurel Avenue South 200 Laurel Avenue South
Middletown,, NJ 07748 Middletown, NJ 07748
USA USA
Phone: +1 732 420 1239 Phone: +1 732 420 1239
Fax: EMail: lencia@att.com
Email: lencia@att.com
URI:
 End of changes. 108 change blocks. 
241 lines changed or deleted 228 lines changed or added

This html diff was produced by rfcdiff 1.40. The latest version is available from http://tools.ietf.org/tools/rfcdiff/