Network Working Group A. Morton Internet-Draft AT&T Labs Updates: 5357 (if approved) K. Hedayat Intended status: Standards Track EXFO Expires: November 6, 2009 May 5, 2009 More Features for the Two-Way Active Measurement Protocol - TWAMP draft-ietf-ippm-more-twamp-01 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. 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 November 6, 2009. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. Morton & Hedayat Expires November 6, 2009 [Page 1]
Internet-Draft TWAMP Extensions May 2009 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This memo describes a simple extension to TWAMP - the Two-Way Active Measurement Protocol. The extension adds the option to use different security modes in the TWAMP-Control and TWAMP-Test protocols simultaneously. The memo also requests that IANA establish a registry for additional new features, called the TWAMP-Modes registry. Requirements Language 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]. Morton & Hedayat Expires November 6, 2009 [Page 2]
Internet-Draft TWAMP Extensions May 2009 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . 4 3. TWAMP Control Extensions . . . . . . . . . . . . . . . . . . . 4 3.1. Extended Control Connection Setup . . . . . . . . . . . . . 5 4. Extended TWAMP Test . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Sender Behavior . . . . . . . . . . . . . . . . . . . . . . 7 4.1.1. Packet Timings . . . . . . . . . . . . . . . . . . . . 7 4.1.2. Packet Format and Content . . . . . . . . . . . . . . . 7 4.2. Reflector Behavior . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 6.1. Registry Specification . . . . . . . . . . . . . . . . . . 8 6.2. Registry Management . . . . . . . . . . . . . . . . . . . . 8 6.3. Experimental Numbers . . . . . . . . . . . . . . . . . . . 8 6.4. Initial Registry Contents . . . . . . . . . . . . . . . . . 8 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 8. Normative References . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Morton & Hedayat Expires November 6, 2009 [Page 3]
Internet-Draft TWAMP Extensions May 2009 1. Introduction The Two-Way Active Measurement Protocol, TWAMP [RFC5357] is an extension of the One-way Active Measurement Protocol, OWAMP [RFC4656]. 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 that are designed to test implementations for protocol compliance. This memo describes a simple extension for TWAMP, the option to use different security modes in the TWAMP-Control and TWAMP-Test protocols (mixed security mode). It also requests that IANA establish a registry for additional new features, called the TWAMP- Modes registry. When the Server and Control-Client have agreed to use the mixed security mode during control connection setup, then the Control- Client, the Server, the Session-Sender and the Session-Reflector MUST all conform to the requirements of this mode as described in sections 3, 4, and 5. This memo updates [RFC5357]. 2. Purpose and Scope The purpose of this memo is to describe and specify an extension for TWAMP [RFC5357], and request the establishment of a registry for future TWAMP extensions. The scope of the memo is limited to specifications of the following: o Extension of the modes of operation through assignment of one new value in the Mode field (see section 3.1 of [RFC4656]), while retaining backward compatibility with TWAMP [RFC5357] implementations. This value adds the OPTIONAL ability to use different security modes in the TWAMP-Control and TWAMP-Test protocols. The motivation for this extension is to permit the low packet rate TWAMP-Control protocol to utilize a stronger mode of integrity protection than that used in the TWAMP-Test protocol. 3. TWAMP Control Extensions TWAMP-Control protocol is a derivative of the OWAMP-Control protocol, and coordinates a two-way measurement capability. All TWAMP Control Morton & Hedayat Expires November 6, 2009 [Page 4]
Internet-Draft TWAMP Extensions May 2009 messages are similar in format and follow similar guidelines to those defined in section 3 of [RFC4656] with the exceptions described in TWAMP [RFC5357], and in the following sections. All OWAMP-Control messages apply to TWAMP-Control, except for the Fetch Session command. 3.1. Extended Control Connection Setup TWAMP-Control connection establishment follows the same procedure defined in section 3.1 of [RFC4656]. This extended mode assigns one new bit position (and value) to allow the Test protocol security mode to operate in Unauthenticated mode, while the Control protocol operates in Encrypted mode. With this extension, the complete set of TWAMP Mode 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) Encrypted CONTROL In the original OWAMP and TWAMP Modes field, setting bit position 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]). In this extension to TWAMP, when the Control-Client sets Modes Field bit position 3, it SHALL discontinue the inheritance of the security mode in the Test protocol, and each protocol's mode SHALL be as specified below. When the desired TWAMP-Test protocol mode is identical to the Control Session mode, the corresponding Modes Field bit (position 0, 1 or 2) SHALL be set by the Control-Client. The table below gives the various combinations of integrity protection that are permissible in TWAMP (with this extension). The TWAMP- Control and TWAMP-Test protocols SHALL use the mode in each column corresponding to the bit position set in the Modes Field. Morton & Hedayat Expires November 6, 2009 [Page 5]
Internet-Draft TWAMP Extensions May 2009 -------------------------------------------------------- Protocol | Permissible Mode Combinations (Modes bit set) -------------------------------------------------------- Control | Unauth.(0)| Auth. == Encrypted (1,2,3) -------------------------------------------------------- | Unauth.(0)| Unauth. (3) ----------------------------------------------- Test | | Auth.(1) ----------------------------------------------- | | Encrypted (2) -------------------------------------------------------- Note that the TWAMP-Control protocol security measures are identical in the Authenticated and Encrypted Modes. Therefore, only one new bit position (3) is needed to convey the single mixed security mode. The value of the Modes Field sent by the Server in the Server- Greeting message is the bit-wise OR of the modes (bit positions) that it is willing to support during this session. Thus, the last four bits of the Modes 32-bit Field are used. When no other features are activated, the first 28 bits MUST be zero. A client conforming to this extension of [RFC5357] MAY ignore the values in the first 28 bits of the Modes Field, or it MAY support other features that are communicated in these bit positions. Other ways in which TWAMP extends OWAMP are described in [RFC5357]. 4. Extended TWAMP Test The TWAMP test protocol is similar to the OWAMP [RFC4656] 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 [RFC5357] 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 that also determine the test packet format: unauthenticated, authenticated, and encrypted. This TWAMP extension makes it possible to use TWAMP-Test Unauthenticated mode regardless of the mode used in the TWAMP-Control protocol. This section describes OPTIONAL extensions. When the Server has identified the ability to support the mixed security mode, the Control-Client has selected the mixed security mode in its Set-Up- Response, and the Server responds with a zero Accept field in the Server-Start message, then these extensions are conditionally REQUIRED. Morton & Hedayat Expires November 6, 2009 [Page 6]
Internet-Draft TWAMP Extensions May 2009 4.1. Sender Behavior This section describes extensions to the behavior of the TWAMP Session-Sender. 4.1.1. Packet Timings The Send Schedule is not utilized in TWAMP, and there are no extensions defined in this memo. 4.1.2. Packet Format and Content The Session-Sender packet format and content MUST follow the same procedure and guidelines as defined in section 4.1.2 of [RFC4656] and section 4.1.2 of [RFC5357], with the following exceptions: o the Send Schedule is not used, and o the Session-Sender MUST support the mixed security mode (Unauthenticated TEST, Encrypted CONTROL,value 8, bit position 3) defined in section 3.1 of this memo. 4.2. Reflector Behavior The TWAMP Session-Reflector is REQUIRED to follow the procedures and guidelines in section 4.2 of [RFC5357], with the following extensions: o the Session-Reflector MUST support the mixed security mode (Unauthenticated TEST, Encrypted CONTROL,value 8, bit position 3) defined in section 3.1 of this memo. 5. Security Considerations The extended mixed-mode of operation permits stronger security/ integrity protection on the TWAMP-Control protocol while simultaneously emphasizing accuracy or efficiency on the TWAMP-Test protocol, thus making it possible to increase 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] and [RFC5357]. Morton & Hedayat Expires November 6, 2009 [Page 7]
Internet-Draft TWAMP Extensions May 2009 6. IANA Considerations This memo adds one security mode bit position/value beyond those in the OWAMP-Control specification[RFC4656], and describes behavior when the new mode is used. This memo requests creation of an IANA registry for the TWAMP Modes field. This field is a recognized extension mechanism for TWAMP. 6.1. Registry Specification 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] and section 3.1 of [RFC5357], 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 bit positions and corresponding values. 6.2. Registry Management Because the TWAMP-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 [RFC5226](an RFC documenting registry use that is approved by the IESG). For the TWAMP-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. 6.3. Experimental Numbers No experimental values are currently assigned for the Modes Registry. 6.4. Initial Registry Contents TWAMP Modes Registry Morton & Hedayat Expires November 6, 2009 [Page 8]
Internet-Draft TWAMP Extensions May 2009 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 Encrypted CONTROL 7. Acknowledgements The authors would like to thank Len Ciavattone for helpful review and comments. 8. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, "A One-way Active Measurement Protocol (OWAMP)", RFC 4656, September 2006. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", RFC 5357, October 2008. Morton & Hedayat Expires November 6, 2009 [Page 9]
Internet-Draft TWAMP Extensions May 2009 Authors' Addresses 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 EXFO 285 Mill Road Chelmsford, MA 01824 USA Phone: +1 Fax: +1 Email: khedayat@exfo.com URI: http://www.exfo.com/ Morton & Hedayat Expires November 6, 2009 [Page 10]
