Internet Engineering Task Force Rajesh Kumar (Editor) INTERNET-DRAFT Cisco Systems draft-rajeshkumar-avt-v150-registration-00.txt August 16, 2002 Expires: February 16, 2003 IANA Registration of parameters and MIME types in proposed ITU Recommendation V.150 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. Abstract This document defines a framework and basis for the IANA registration of parameters defined in the ITU V.150 recommendation, which addresses the transmission of modem signals over IP. This includes both modem passthrough and modem relay operation. As a framework document, this internet draft leaves the details of the modem-over-IP (MoIP) protocols and formats to the ITU V.150 recommendation. Since the V.150 recommendation is work in progress by ITU SG16/Q11, registration of these parameters is contingent upon its impending ratification. Although these parameters are meant for use in text-based control protocols such as SDP, equivalent reformulations are planned for non-text protocols such as ITU H.245. Kumar et al August 2002 Page 1 IANA Registration of ITU V.150 Parameters and MIMEs 1. Introduction.............................................................2 2. Registration of the UDPSPRT transport protocol..........................2 3. Registration of new SDP attributes.......................................3 4. Registration of new MIME types...........................................3 4.1 Registration of the audio/v150mr MIME type.............................3 4.2 Registration of the audio/v150fw MIME type.............................6 5. Security Considerations..................................................7 6. IANA Considerations......................................................7 7. Acknowledgements.........................................................7 8. References...............................................................8 9. Authors' Addresses.......................................................9 1. Introduction The ITU V.150 recommendation is meant to standardize, in a comprehensive manner, the encapsulation of modem signals within IP. This includes both modem passthrough and modem relay operation. Although this internet draft is a first-cut application for the IANA registration of ITU V.150 parameters, the underlying ITU V.150 protocols and media formats it refers to reflect the current consensus of the TIA TR.30.1 (ITU SG16/Q11) study groups. These protocols and media formats have been crafted over a period of about two years and several meetings of modem experts, and are close to finalization. The following classes of parameters defined in ITU V.150 recommendation warrant IANA registration: 1. A new transport protocol, UDPSPRT (Simple Packet Relay Transport over UDP). 2. New SDP attributes that qualify media streams associated with modem-over- IP. These may be modem passthrough or modem relay media streams. 3. New MIME types: audio/v150mr and audio/v150fw. These indicate media formats defined, in the ITU V.150 recommendation, for use in the modem- over-IP context. This document is initially submitted to the IETF's AVT working group because of the presence of new MIME definitions. Review by the IETF's MMUSIC working group is also solicited. 2. Registration of the UDPSPRT transport protocol UDSPRT, Simple Packet Relay Transport over UDP, is a reliable protocol that can be used to efficiently guarantee packet delivery in an IP network that is prone to packet loss. Kumar et al August 2002 Page 2 IANA Registration of ITU V.150 Parameters and MIMEs In a manner similar to the UDPTL protocol [3], UDPSRPT should be registered as a value of the SDP parameter "proto", referring to the transport protocol. Details of the UDPSPRT protocol are found in [1]. 3. Registration of new SDP attributes The ITU V.150 recommendation defines several new SDP attributes. These should be registered as values of the SDP parameter "att-field" parameter. These are: 1. sprtparm, which lists parameters associated with the UDPSRPT protocol. 2. sprtmap, which dynamically defines a numerical identifier for modem relay packets. 3. vndpar, used to pass vendor-specific parameters. 4. gfmtp, based on its definition [2]. This is used to dynamically associate, with a format, parameters that are not embedded in the MIME definition of that format. In addition to being listed as an SDP attribute, 'gfmtp' warrants a new IANA registry of its own since new non-MIME parameters may be deemed useful and defined in the future. Details of these attributes are found in [1]. 4. Registration of new MIME types 4.1 Registration of the audio/v150mr MIME type This MIME represents the modem relay packet format as defined in the ITU V.150 recommendation. Hence the suffix 'mr' (modem relay). MIME media type name: audio MIME subtype name: v150mr Required parameters: mr: the type of modem relay, from the set "v8" (ITU V.8-compatible) and "u" (universal). mg: the type of media gateway, from the set "0" (No Transcompression), "1" (Single Transcompression) and "2" (Double Transcompression. Optional parameters: versn: Version of the ITU V.150 recommendation used. Dotted representation, x.y, where the integer 'x' is the main version number ('1' for V.150.1) and the integer 'y' is the sub-version Kumar et al August 2002 Page 3 IANA Registration of ITU V.150 Parameters and MIMEs number. jmdelay: indicates whether the JM delay procedures for end-to-end XID exchange are enabled or not. Permissible values are "yes" and "no". mrmods: This parameter lists supported modulation types. These are listed as one or mote comma-separated elements. Each element can either be a single integer or two integers separated by a hyphen. No white space is allowed. The integers, which designate modulation types are from the set "1" (V.34 duplex), "2" (V.34 Half-duplex), "3" (V.32bis/V.32), "4" (V.22bis/V.22), "5" (V.17), "6" (V.29 half- duplex), "7" (V.27 ter), "8" (V.26 ter), "9" (V.26bis), "10" (V.23 duplex), "11" (V.23 half duplex), "12" (V.21), "13" (V.90 analog), "14" (V.90 digital), "15" (V.91), "16" (V.92 analog) and "17" (V.92 digital). txalgs: This parameter lists supported transcompression algorithms. These are listed as one or mote comma-separated elements. Each element can either be a single integer or two integers separated by a hyphen. No white space is allowed. The integers, which designate transcompression algorithms are from the set "1" (V.44), "2" (V.42bis) and "3" (MNP5). The default is "2". v42maxdict: Maximum V.42 dictionary size. Value range and default TBD. v42maxstring: Maximum V.42 string size. Value range and default TBD. v44maxtdict: Maximum V.44 transmit dictionary size. Value range and default TBD. v44maxtstring: Maximum V.44 transmit string size. Value range and default TBD. v44maxrdict: Maximum V.44 receive dictionary size. Value range and default TBD. v44maxrstring: Maximum V.44 receive string size. Value range and default TBD. v44maxthist: Maximum V.44 transmit history size. Value range and default TBD. v44maxrhist: Maximum V.44 receive history size. Value range and default TBD. Encoding considerations: The MIME audio/v150mr uses the UDPSPRT (Simple Packet Relay Transport over UDP) reliable transport protocol as defined in the ITU V.150 recommendation. As such, it consists of packets of binary data. Security considerations: The privacy and integrity of the data transmitted via V.150 modem relay must be ensured at the application level by means such as encryption. The V.150 modem relay protocol does not hinder such end- to-end data protection. Nor does it provide any additional, inbuilt safeguards that can be used in the absence of end-to-end, application-level data security. The transcompression and other algorithms used in V.150 modem relay are published in various standards and can be implemented by a resourceful attacker. Kumar et al August 2002 Page 4 IANA Registration of ITU V.150 Parameters and MIMEs Likewise, V.150 modem relay procedures do not address session authentication, which must be handled end-to-end by client and server authentication applications. Authentication is out of the scope of a bearer-level protocol such as V.150 modem relay. Resource usage by a modem relay session may be monitored to prevent denial of service attacks. The resource utilization of modem relay sessions does not exhibit such non-uniformity so as to preclude such resource limiting. The MIME type contains no executable content that affects sessions or session legs other than the ones in which the requester is a participant. For these session legs, executable content in the form of modem relay control messages is well within the normal prerogatives of the requester. Like other encodings with open-ended content, the ITU V.150 modem relay format may be abused by hiding data using steganography. However, due to its more limited context, it is unlikely that it will be preferred for such misuse vis-a-vis other audio and video encodings. Interoperability considerations: Interoperability is limited to endpoints or gateways that implement the mandatory parts of the ITU V.150 recommendation, "Procedures for the end-to-end connection of V-series DCEs over an IP Network". Backward compatibility will be maintained between all versions of this recommendation. Published specification: The ITU V.150.1 specification, to be published. Applications which use this media: Endpoints and media gateways that interface with V-series modems on one end, and with an IP network on the other end. In this case, the on-ramp gateway does not support full modem termination which would have allowed forwarding via a higher-layer protocol. Additional information: 1. Magic number(s): N/A 2. File extension(s): N/A 3. Macintosh file type code: N/A Kumar et al August 2002 Page 5 IANA Registration of ITU V.150 Parameters and MIMEs 4.2 Registration of the audio/v150fw MIME type This MIME represents the format of messages used to define the overall framework of modem-over-IP operation as defined in the ITU V.150 recommendation. Hence the suffix 'fw' (framework). MIME media type name: audio MIME subtype name: v150fw Required parameters: None. Optional parameters: messages: The "messages" parameter lists the framework messages supported by the media gateway or endpoint. Messages are listed as one or more comma-separated elements. Each element can either be a single integer or two integers separated by a hyphen. No white space is allowed. The integers, which identify messages types are from the set "0" (null), "1" (initialize), "2" (voiceband data), "3" (modem relay), "4" (text relay), "5" (fax relay). When omitted, the default is 0-4. Encoding considerations: Like all other ITU V.150 media formats except modem relay, the MIME audio/v150fw uses the RTP protocol. As such, it consists of packets of binary data. The RTP payload is defined in the ITU V.150 recommendation. Security considerations: As with other RTP formats, it is possible to use IPSEC to ensure the authenticity, integrity and privacy of this media format. Since this media format is uncompressed, there is no potential conflict between compression and encryption. Many applications use modem relay between trusted network equipment and, as such, may forego the use of IPSEC. When used with equipment in untrusted areas, the impact of the V.150 framework messages is limited to one session. Hence, any exposure from not encrypting this media format is limited. Resource usage by V.150 framework messages may be monitored to prevent denial of service attacks. Since the resource utilization of these messages is minimal, resource limiting is not precluded. The MIME type contains no executable content that affects sessions or session legs other than the ones in which the requester is a participant. For these session legs, executable content in the form of V.150 framework messages is well within the normal prerogatives of the requester. Kumar et al August 2002 Page 6 IANA Registration of ITU V.150 Parameters and MIMEs Since the content associated with this MIME type is well-defined and not open-ended, it is not vulnerable to hiding data using steganography. Interoperability considerations: Interoperability is limited to endpoints or gateways that implement the mandatory parts of the ITU V.150 recommendation, "Procedures for the end-to-end connection of V-series DCEs over an IP Network". Backward compatibility will be maintained between all versions of this recommendation. Published specification: The ITU V.150.1 specification, to be published. Applications which use this media: Endpoints and media gateways that interface with V-series modems on one end, and with an IP network on the other end. In this case, the on-ramp gateway does not support full modem termination which would have allowed forwarding via a higher-layer protocol. Additional information: 1. Magic number(s): N/A 2. File extension(s): N/A 3. Macintosh file type code: N/A 5. Security Considerations This document does not impose any security considerations of its own, apart from the security considerations associated with each MIME type is contains. 6. IANA Considerations The entirety of this document is for IANA review and is limited to such information as pertinent to the IANA registration of MIME types and SDP parameters. For the creation of a separate registry for the 'gfmtp' parameter, see [2]. 7. Acknowledgements The entirety of the TIA TR.30.1(ITU SG16/Q11) teams led by Les Brown in the past and Ken Chu currently. Detailed review of and indispensable contribution towards of the ITU V.150 SDP definition by Flemming Andreasen, Bill Foster and Dave Oran. Kumar et al August 2002 Page 7 IANA Registration of ITU V.150 Parameters and MIMEs Jim Renkel who suggested the creation of a 'manyfolks' internet draft leading to an RFC that highlighted the IANA registration requirements of the ITU V.150 recommendation. Advice from Colin Perkins regarding the creation of a new 'gfmtp' registry is acknowledged. 8. References [1] ITU V.150.1, Procedures for the end-to-end connection of V-series DCEs over an IP Network, work-in-progress, http://ftp.tiaonline.org/TR-30/TR301/Public. [2] Generic format parameter, draft-rajeshkumar-mmusic-gfmtp-02.txt. [3] ITU T.38, Procedures for real-time Group 3 facsimile communication over IP networks. Kumar et al August 2002 Page 8 IANA Registration of ITU V.150 Parameters and MIMEs 9. Authors' Addresses Rajesh Kumar Cisco Systems 170 West Tasman Dr San Jose, CA Phone: +1 408 527 0811 Email: rkumar@cisco.com Jim Renkel The CommWorks Corporation, a 3COM company Office: +1.847.262.2539 E-mail: james_renkel@commworks.com Fred Lucas, Chair TIA TR-30 FAL Associates 3421 Buttonwood Court Reisterstown, MD 21136-4401 Tel: 410-239-0248 Email: fred.lucas@ieee.org Keith Chu TIA TR-30.1 (MoIP) chair Conexant Systems Phone: +1 (949) 579-4121 Fax: +1 (949) 579-3667 Email: keith.chu@mindspeed.com Michael Nicholas 3COM E-mail: michael_nicholas@3com.com Herb Wildfeuer Cisco Systems, Inc. hwildfeu@cisco.com (805)961-3620 Adrian Zakrzewski Texas Instruments, Inc. azakrzewski@ti.com (301)515-6636 Frank Chen Conexant Systems Phone: +1 (949) 579-3296 Fax: +1 (949) 579-3667 Email: frank.chen@mindspeed.com Mario (Mehryar) Garakani Kumar et al August 2002 Page 9 IANA Registration of ITU V.150 Parameters and MIMEs Cisco Systems Phone: +1 (805) 961-3640 Email: mgarakan@cisco.com Alex Urquizo Cisco Systems Office: 1-978-936-0172 E-mail: aurquizo@cisco.com Nate Melhorn Cisco Systems Office: +1.978.936.0144 Email: nmelhorn@cisco.com Dan DeLiberatto Cisco Systems Email: ddeliber@cisco.com Hisham Abdelhamid Cisco Systems Email: hisham@cisco.com Mohamed Mostafa Office: +1.408.525.2378 Cisco Systems Email: mmostafa@cisco.com Other members of TIA TR.30.1 whose names will be added in a future revision. 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