| TOC |
|
By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work in progress.”
The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html.
This Internet-Draft will expire on January 8, 2009.
The IETF is completing its work on TWAMP - the Two-Way Active Measurement Protocol. This memo describes additional features for TWAMP, essentially the ability to use different security modes in the TWAMP-Control and TWAMP-Test protocols.
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 (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.) [RFC2119].
1.
Introduction
2.
Purpose and Scope
3.
TWAMP Control Extensions
3.1.
Extended Connection Setup
4.
Extended TWAMP Test
4.1.
Sender Behavior
4.1.1.
Packet Timings
4.1.2.
Packet Format and Content
4.2.
Reflector Behavior
5.
Security Considerations
6.
IANA Considerations
6.1.
Registry Specification
6.2.
Registry Management
6.3.
Experimental Numbers
6.4.
Initial Registry Contents
7.
Acknowledgements
8.
References
8.1.
Normative References
8.2.
Informative References
§
Authors' Addresses
§
Intellectual Property and Copyright Statements
| TOC |
The IETF is completing its work on TWAMP - the Two-Way Active Measurement Protocol [I‑D.ietf‑ippm‑twamp] (Babiarz, J., “A Two-way Active Measurement Protocol (TWAMP),” August 2008.), which is an extension to the One-way Active Measurement Protocol, OWAMP [RFC4656] (Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” September 2006.). The TWAMP specification gathered wide review as it approached completion, and the by-products were several recommendations for new features in TWAMP. There are a growing number TWAMP implementations at present, and wide-spread usage is expected. There are even devices emerging that test implementations for protocol compliance.
This memo describes additional features for TWAMP, such as the ability to use different security modes in the TWAMP-Control and TWAMP-Test protocols.
The relationship between this memo and the TWAMP is intended to be an update to the TWAMP RFC when published.
| TOC |
The purpose of this memo is to specify additional functions and features for TWAMP [I‑D.ietf‑ippm‑twamp] (Babiarz, J., “A Two-way Active Measurement Protocol (TWAMP),” August 2008.). The features and extensions were vetted before adoption in this memo.
The scope of the memo is limited to specifications of the following features:
(other items may be added)
| TOC |
TWAMP-Control protocol is a derivative of the OWAMP-Control protocol, and provides two-way measurement capability. All TWAMP Control messages are similar in format and follow similar guidelines to those defined in section 3 of [RFC4656] (Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” September 2006.) with the exceptions described in TWAMP [I‑D.ietf‑ippm‑twamp] (Babiarz, J., “A Two-way Active Measurement Protocol (TWAMP),” August 2008.), and in the following sections.
All OWAMP-Control messages apply to TWAMP-Control, except for the Fetch Session command.
| TOC |
TWAMP connection establishment follows the same procedure defined in section 3.1 of [RFC4656] (Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” September 2006.). The extended modes assign three new bit positions (and values) to allow the Test protocol security mode to differ from the Control protocol mode. With this extension, the complete set of TWAMP values are as follows:
Value Description Reference/Explanation
0 Reserved
1 Unauthenticated RFC4656, Section 3.1
2 Authenticated RFC4656, Section 3.1
4 Encrypted RFC4656, Section 3.1
8 Unauth. TEST protocol, new bit position (3)
Auth. CONTROL
16 Unauth. TEST protocol, new bit position (4)
Encrypted CONTROL
32 Auth. TEST protocol, new bit position (5)
Encrypted CONTROL
In the original OWAMP mode field, setting bit positions 0, 1 or 2 indicated the security mode of the Control protocol, and the Test protocol inherited the same mode (see section 4 of [RFC4656] (Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” September 2006.)). In this extension to TWAMP, setting a higher mode field bit position (3, 4 or 5) SHALL discontinue the inheritance of the security mode in the Test protocol, and each protocol’s mode SHALL be specified explicitly. When the desired TWAMP Test protocol mode is identical to the Control Session mode, the corresponding mode bit (position 0, 1 or 2) SHALL be set. The table below gives the various combinations that are now permissible in TWAMP, where the Test protocol may use one of the modes in each column corresponding to a Control mode.
----------------------------------------------------
Protocol | Permissible Mode Combinations
----------------------------------------------------
Control | Unauth. | Auth. | Encrypted
----------------------------------------------------
| Unauth. | Unauth. | Unauth.
-------------------------------------------
Test | | Auth. | Auth.
-------------------------------------------
| | | Encrypted
----------------------------------------------------
The value of the Modes field sent by the Server is the bit-wise OR of the mode values that it is willing to support during this session. Thus, the last six bits of the Modes 32-bit field are used. The first 26 bits MUST be zero. A client conforming to this version of the specification MUST ignore the values in the first 26 bits of the Modes value. (This way, the bits are available for future protocol extensions.)
Other ways in which TWAMP extends OWAMP are described in [I‑D.ietf‑ippm‑twamp] (Babiarz, J., “A Two-way Active Measurement Protocol (TWAMP),” August 2008.).
| TOC |
The TWAMP test protocol is similar to the OWAMP [RFC4656] (Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” September 2006.) test protocol with the exception that the Session-Reflector transmits test packets to the Session-Sender in response to each test packet it receives. TWAMP [I‑D.ietf‑ippm‑twamp] (Babiarz, J., “A Two-way Active Measurement Protocol (TWAMP),” August 2008.) defines two different test packet formats, one for packets transmitted by the Session-Sender and one for packets transmitted by the Session-Reflector. As with OWAMP-Test protocol there are three security modes: unauthenticated, authenticated, and encrypted. The extension to TWAMP makes it possible to specify these modes independently from the mode used in the TWAMP-Control protocol.
| TOC |
This section describes extensions to the behavior of the TWAMP Sender.
| TOC |
The Send Schedule is not utilized in TWAMP, and there are no extensions defined in this memo.
| TOC |
The Session Sender packet format and content follow the same procedure and guidelines as defined in section 4.1.2 of [RFC4656] (Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” September 2006.), with the following exceptions:
| TOC |
The TWAMP Reflector follows the procedures and guidelines in section 4.2 of [I‑D.ietf‑ippm‑twamp] (Babiarz, J., “A Two-way Active Measurement Protocol (TWAMP),” August 2008.), with the following extensions:
| TOC |
These extended modes of operation permit stronger integrity protection on the TWAMP-Control protocol while simultaneously emphasizing accuracy or efficiency on the TWAMP-Test protocol, thus enhancing overall security when compared to the previous options.
The security considerations that apply to any active measurement of live networks are relevant here as well. See [RFC4656] (Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” September 2006.) and [I‑D.ietf‑ippm‑twamp] (Babiarz, J., “A Two-way Active Measurement Protocol (TWAMP),” August 2008.).
| TOC |
This memo adds three security mode combinations to the OWAMP-Control specification[RFC4656] (Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” September 2006.), and describes behavior when the new modes are used. This memo requests creation an IANA registry for the TWAMP Mode field. This field is a recognized extension mechanism for TWAMP.
| TOC |
IANA is requested to create a TWAMP-Modes registry. TWAMP-Modes are specified in TWAMP Server Greeting messages and Set-up Response messages consistent with section 3.1 of [RFC4656] (Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” September 2006.), and extended by this memo. Modes are indicated by setting bits in the 32-bit Modes field. Thus, this registry can contain a total of 32 possible values.
| TOC |
Because the Modes registry can contain only thirty-two values, and because TWAMP is an IETF protocol, this registry must be updated only by "IETF Consensus" as specified in [RFC2434] (Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” October 1998.)(an RFC documenting registry use that is approved by the IESG). For the Modes registry, we expect that new features will be assigned using monotonically increasing bit positions and in the range [0-31] and the corresponding values, unless there is a good reason to do otherwise.
| TOC |
No experimental values are currently assigned for the Modes Registry.
| TOC |
TWAMP Modes Registry
Value Description Semantics Definition
0 Reserved
1 Unauthenticated RFC4656, Section 3.1
2 Authenticated RFC4656, Section 3.1
4 Encrypted RFC4656, Section 3.1
8 Unauth. TEST protocol, this document, Section 3.1
Auth. CONTROL
16 Unauth. TEST protocol, this document, Section 3.1
Encrypted CONTROL
32 Auth. TEST protocol, this document, Section 3.1
Encrypted CONTROL
| TOC |
The authors would like to thank Len Ciavattone for helpful review and comments.
| TOC |
| TOC |
| [I-D.ietf-ippm-twamp] | Babiarz, J., “A Two-way Active Measurement Protocol (TWAMP),” draft-ietf-ippm-twamp-09 (work in progress), August 2008 (TXT). |
| [RFC2119] | Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” BCP 14, RFC 2119, March 1997 (TXT, HTML, XML). |
| [RFC2434] | Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” BCP 26, RFC 2434, October 1998 (TXT, HTML, XML). |
| [RFC4656] | Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, “A One-way Active Measurement Protocol (OWAMP),” RFC 4656, September 2006 (TXT). |
| TOC |
| [x] | “.” |
| TOC |
| Al Morton | |
| 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 |
| URI: | http://home.comcast.net/~acmacm/ |
| Kaynam Hedayat | |
| Brix Networks | |
| 285 Mill Road | |
| Chelmsford, MA 01824 | |
| USA | |
| Phone: | +1 |
| Fax: | +1 |
| Email: | khedayat@brixnet.com |
| URI: | http://www.brixnet.com/ |
| TOC |
Copyright © The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on an “AS IS” basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org.