Internet DRAFT - draft-ietf-ippm-port-twamp-test
draft-ietf-ippm-port-twamp-test
Network Working Group A. Morton, Ed.
Internet-Draft AT&T Labs
Updates: 4656 and 5357 (if approved) G. Mirsky, Ed.
Intended status: Standards Track ZTE Corp.
Expires: June 12, 2019 December 9, 2018
OWAMP and TWAMP Well-Known Port Assignments
draft-ietf-ippm-port-twamp-test-04
Abstract
This memo explains the motivation and describes the re-assignment of
well-known ports for the One-way Active Measurement Protocol and Two-
way Active Measurement Protocol (OWAMP and TWAMP) protocols for
control and measurement, and clarifies the meaning and composition of
these standards track protocol names for the industry.
The memo updates RFC 4656 and RFC 5357, in terms of the UDP well-
known port assignments, and clarifies the complete OWAMP and TWAMP
protocol composition for the industry.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 12, 2019.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Definitions and Background . . . . . . . . . . . . . . . . . 3
5. New Well-Known Ports . . . . . . . . . . . . . . . . . . . . 4
5.1. Impact on TWAMP-Control Protocol . . . . . . . . . . . . 4
5.2. Impact on OWAMP-Control Protocol . . . . . . . . . . . . 5
5.3. Impact on OWAMP/TWAMP-Test Protocols . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7
9. Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . 7
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
11.1. Normative References . . . . . . . . . . . . . . . . . . 8
11.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The IETF IP Performance Metrics (IPPM) working group first developed
the One-Way Active Measurement Protocol, OWAMP, specified in
[RFC4656]. Further protocol development to support testing resulted
in the Two-Way Active Measurement Protocol, TWAMP, specified in
[RFC5357].
Both OWAMP and TWAMP require the implementation of a control and mode
negotiation protocol (OWAMP-Control and TWAMP-Control) which employs
the reliable transport services of TCP (including security
configuration and key derivation). The control protocols arrange for
the configuration and management of test sessions using the
associated test protocol (OWAMP-Test or TWAMP-Test) on UDP transport.
In this memo, IETF recognizes the value of assigning a well-known UDP
port to the *-Test protocols, and that this goal can easily be
arranged through port re-assignments.
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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] [RFC8174] when, and only when, they appear in all capitals,
as shown here.
3. Scope
The scope of this memo is to re-allocate well-known ports for the UDP
Test protocols that compose necessary parts of their respective
standards track protocols, OWAMP and TWAMP, along with clarifications
of the complete protocol composition for the industry.
The memo updates [RFC4656] and [RFC5357], in terms of the UDP well-
known port assignments.
4. Definitions and Background
This section defines key terms and clarifies the required composition
of the OWAMP and TWAMP standards-track protocols.
OWAMP-Control is the protocol defined in Section 3 of [RFC4656].
OWAMP-Test is the protocol defined in Section 4 of [RFC4656].
OWAMP is described in a direct quote from Section 1.1 of[RFC4656]:
"OWAMP actually consists of two inter-related protocols: OWAMP-
Control and OWAMP-Test." A similar sentence appears in Section 2 of
[RFC4656]. For avoidance of doubt, implementation of both OWAMP-
Control and OWAMP-Test are REQUIRED for standards-track OWAMP
specified in [RFC4656] (aplying the consensus of many dictionary
definitions of "consist").
TWAMP-Control is the protocol defined in Section 3 of [RFC5357].
TWAMP-Test is the protocol defined in Section 4 of [RFC5357].
TWAMP is described in a direct quote from Section 1.1 of [RFC5357]:
"Similar to OWAMP [RFC4656], TWAMP consists of two inter-related
protocols: TWAMP-Control and TWAMP-Test." For avoidance of doubt,
implementation of both TWAMP-Control and TWAMP-Test are REQUIRED for
standards-track TWAMP specified in [RFC5357] (aplying the consensus
of many dictionary definitions of "consist").
TWAMP Light is an idea described in Informative Appendix I of
[RFC5357], and includes an un-specified control protocol combined
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with the TWAMP-Test protocol. The TWAMP Light idea was relegated to
the Appendix because it failed to meet the requirements for IETF
protocols (there are no specifications for negotiating this form of
operation, and no specifications for mandatory-to-implement security
features), as described in Appendix A of this memo, which cites
[LarsAD] and [TimDISCUSS] .
Since the idea of TWAMP Light clearly includes the TWAMP-Test
component of TWAMP, it is considered reasonable for future systems to
use the TWAMP-Test well-known UDP port (whose re-allocated assignment
is requested here). Clearly, the TWAMP Light idea envisions many
components and communication capabilities beyond TWAMP-Test
(implementing the security requirements, for example), otherwise
Appendix I of [RFC5357] would be one sentence long (equivocating
TWAMP Light with TWAMP-Test only).
5. New Well-Known Ports
Originally, both TCP and UDP well-known ports were assigned to the
control protocols that are essential components of standards track
OWAMP and TWAMP.
Since OWAMP-Control and TWAMP-Control require TCP transport, they
cannot make use of the UDP ports which were originally assigned.
However, test sessions using OWAMP-Test or TWAMP-Test operate on UDP
transport.
This memo requests re-assignment of the UDP well-known port from the
Control protocol to the Test protocol (see the IANA Considerations
Section 7). Use of this UDP port is OPTIONAL in standards-track
OWAMP and TWAMP. It may simplify some operations to have a well-
known port available for the Test protocols, or for future
specifications involving TWAMP-Test to use this port as a default
port. For example, [TR-390] is a specification for testing at the
customer edge of IP networks, and whose implememntations should
benefit.
5.1. Impact on TWAMP-Control Protocol
Section 3.5 [RFC5357] describes the detailed process of negotiating
the Receiver Port number, on which the TWAMP Session-Reflector will
send and receive TWAMP-Test packets. The Control-Client, acting on
behalf of the Session-Sender, proposes the Receiver port number from
the Dynamic Port range [RFC6335]:
"The Receiver Port is the desired UDP port to which TWAMP-Test
packets will be sent by the Session-Sender (the port where the
Session-Reflector is asked to receive test packets). The Receiver
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Port is also the UDP port from which TWAMP-Test packets will be
sent by the Session-Reflector (the Session-Reflector will use the
same UDP port to send and receive packets)."
It is possible that the proposed Receiver Port may be not available,
e.g., the port is in use by another test session or another
application. In this case:
"... the Server at the Session-Reflector MAY suggest an alternate
and available port for this session in the Port field. The
Control-Client either accepts the alternate port, or composes a
new Session-Request message with suitable parameters. Otherwise,
the Server uses the Accept field to convey other forms of session
rejection or failure to the Control Client and MUST NOT suggest an
alternate port; in this case, the Port field MUST be set to zero."
A Control Client that supports use of the allocated TWAMP-Test
Receiver Port Section 7 MAY request to use that port number in the
Request-TW-Session Command. If the Server does not support the
allocated TWAMP-Test Receiver Port, then it sends an alternate port
number in the Accept-Session message with Accept field = 0. Thus the
deployment of the allocated TWAMP Receiver Port number is backward
compatible with existing TWAMP-Control solutions that are based on
[RFC5357]. Of course, use of a UDP port number chosen from the
Dynamic Port range [RFC6335] will help to avoid the situation when
the Control-Client or Server finds the proposed port being already in
use.
5.2. Impact on OWAMP-Control Protocol
As described above, an OWAMP Control Client that supports use of the
allocated OWAMP-Test Receiver Port Section 7 MAY request to use that
port number in the Request-Session Command. If the Server does not
support the allocated OWAMP-Test Receiver Port (or does not have the
port available), then it sends an alternate port number in the
Accept-Session message with Accept field = 0. Further exchanges
proceed as already specified.
5.3. Impact on OWAMP/TWAMP-Test Protocols
OWAMP/TWAMP-Test may be used to measure IP performance metrics in an
Equal Cost Multipath (ECMP) environment. Though algorithms to
balance IP flows among available paths have not been standardized,
the most common is the five-tuple that uses destination IP address,
source IP address, protocol type, destination port number, and source
port number. When attempting to monitor different paths in ECMP
network, it is sufficient to vary only one of five parameters, e.g.
the source port number. Thus, there will be no negative impact on
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ability to arrange concurrent OWAMP/TWAMP test sessions between the
same test points to monitor different paths in the ECMP network when
using the re-allocated UDP port number as the Receiver Port, as use
of the port is optional.
6. Security Considerations
The security considerations that apply to any active measurement of
live paths are relevant here as well (see [RFC4656] and [RFC5357]).
When considering privacy of those involved in measurement or those
whose traffic is measured, the sensitive information available to
potential observers is greatly reduced when using active techniques
which are within this scope of work. Passive observations of user
traffic for measurement purposes raise many privacy issues. We refer
the reader to the security and privacy considerations described in
the Large Scale Measurement of Broadband Performance (LMAP) Framework
[RFC7594], which covers both active and passive techniques.
The registered UDP port as the Receiver Port for OWAMP/TWAMP-Test
could become a target of denial-of-service (DoS), or used to aid man-
in-the-middle (MITM) attacks. To improve protection from the DoS
following methods are recommended:
o filtering access to the OWAMP/TWAMP Receiver Port by access list;
o using a non-globally routable IP address for the OWAMP/TWAMP
Session-Reflector address.
A MITM attack may try to modify the content of the OWAMP/TWAMP-Test
packets in order to alter the measurement results. However, an
implementation can use authenticated mode to detect modification of
data. In addition, use encrypted mode to prevent eavesdropping and
un-detected modification of the OWAMP/TWAMP-Test packets.
There is also a risk of a network under test giving special treatment
to flows involving the well-known UDP port, with or without knowing
source and destination addresses of measurement systems, and thus
biasing the results through preferential or detrimental processing.
7. IANA Considerations
This memo requests re-allocation of two UDP port numbers from the
System Ports range [RFC6335]. Specifically, this memo requests that
IANA re-allocate UDP ports 861 and 862 as shown below, leaving the
TCP port assignments as-is:
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+------------+-------+---------+----------------------+-------------+
| Service | Port | Transp. | Description | Reference |
| Name | Num. | Protocol| | |
| | | | | |
+------------+-------+---------+----------------------+-------------+
| owamp- | 861 | tcp | OWAMP-Control | [RFC4656] |
| control | | | | |
| owamp-test | 861 | udp | OWAMP-Test | [RFCXXXX] |
| | | | | |
| twamp- | 862 | tcp | TWAMP-Control | [RFC5357] |
| control | | | | |
| twamp-test | 862 | udp | TWAMP-Test Receiver | [RFCXXXX] |
| | | | Port | |
+------------+-------+---------+----------------------+-------------+
Table 1 Re-allocated OWAMP and TWAMP Ports
where RFCXXXX is this memo when published. The Assignee and Contact
should information be updated as follows:
Assignee: IESG
Contact: IETF Chair
8. Contributors
Richard Foote and Luis M. Contreras made notable contributions on
this topic.
9. Appendix A
This informative Appendix provides the Background on the decision to
move the TWAMP Light idea to an informative Appendix in [RFC5357].
The TWAMP Light idea was relegated to the Appendix because it failed
to meet the requirements for IETF protocols (there are no
specifications for negotiating this form of operation, and no
specifications for mandatory-to-implement security features), as
described in the references below:
o Lars Eggert's Area Director review [LarsAD], where he pointed out
that having two variants of TWAMP, Light and Complete (called
standards track TWAMP here), required a protocol mechanism to
negotiate which variant will be used. See Lars' comment on Sec
5.2. The working group consensus was to place the TWAMP Light
description in Appendix I, and to refer to the Appendix only as an
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"incremental path to adopting TWAMP, by implementing the TWAMP-
Test protocol first".
o Tim Polk's DISCUSS Ballot, which points out that TWAMP Light was
an incomplete specification because the key required for
authenticated and encrypted modes depended on the TWAMP-Control
Session key. See Tim's DISCUSS on 2008-07-16 [TimDISCUSS].
Additional requirement statements were added in the Appendix to
address Tim's DISCUSS Ballot (see the last three paragraphs of
Appendix I in [RFC5357]).
Since the idea of TWAMP Light clearly includes the TWAMP-Test
protocol and other undefined facilities, Appendix I of [RFC5357]
simply describes ideas of how TWAMP-Test might be used ouside of the
context of Standards-Track TWAMP.
10. Acknowledgements
The authors thank the IPPM working group for their rapid review; also
Muthu Arul Mozhi Perumal and Luay Jalil for their participation and
suggestions.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,
<https://www.rfc-editor.org/info/rfc4656>.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, DOI 10.17487/RFC5357, October 2008,
<https://www.rfc-editor.org/info/rfc5357>.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165,
RFC 6335, DOI 10.17487/RFC6335, August 2011,
<https://www.rfc-editor.org/info/rfc6335>.
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[RFC7594] Eardley, P., Morton, A., Bagnulo, M., Burbridge, T.,
Aitken, P., and A. Akhter, "A Framework for Large-Scale
Measurement of Broadband Performance (LMAP)", RFC 7594,
DOI 10.17487/RFC7594, September 2015,
<https://www.rfc-editor.org/info/rfc7594>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
11.2. Informative References
[LarsAD] "https://mailarchive.ietf.org/arch/msg/ippm/
LzcTPYhPhWhbb5-ncR046XKpnzo", April 2008.
[TimDISCUSS]
"https://datatracker.ietf.org/doc/rfc5357/history/", July
2008.
[TR-390] "TR-390 Performance Measurement from IP Edge to Custom er
Equipment using TWAMP Light, Issue: 1", May 2017,
<https://www.broadband-forum.org/technical/download/
TR-390.pdf>.
Authors' Addresses
Al Morton (editor)
AT&T Labs
200 Laurel Avenue South
Middletown, NJ 07748
USA
Phone: +1 732 420 1571
Fax: +1 732 368 1192
Email: acmorton@att.com
Greg Mirsky (editor)
ZTE Corp.
Email: gregimirsky@gmail.com
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