Internet Engineering Task Force Rajesh Kumar (Editor) INTERNET-DRAFT Cisco Systems draft-kumar-avt-v150-registration-02.txt October 29, 2002 Expires: April 29, 2003 IANA Registration of MIME types and SDP parameters in proposed ITU Recommendation V.150.1 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 for the IANA registration of MIME types and SDP parameters defined in the ITU V.150.1 recommendation. For SDP parameters, it does not repeat the details of syntax and semantics found in the ITU recommendation. For the MIME types, it provides RFC 2048-compliant MIME definitions which refer to the ITU V.150.1 recommendation for detailed format description. Until the ITU V.150.1 recommendation is ratified, this document should be considered work in progress. 1. Introduction.............................................................1 2. Overview of Parameters to be registered....................................2 3. Registration of new SDP parameters.......................................3 3.1 Registration of the 'udpsprt' transport protocol.......................3 3.2 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.............................7 5. Security Considerations..................................................8 6. IANA Considerations......................................................8 7. Acknowledgements.........................................................8 8. References...............................................................9 9. Authors' Addresses......................................................10 1. Introduction Kumar et al September 2002 Page 1 IANA Registration of ITU V.150.1 MIMEs and SDP parameters There is a need to register ITU V.150.1 parameters with the IANA/ICANN. These include (i) SDP parameters, and (ii) MIME types. The IANA registration of MIME subtypes types in the IETF tree requires an RFC approved by the IESG. This document is meant to fulfill that role. The ITU V.150.1 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. The ITU V.150.1 recommendation, which has been crafted over a period of about two years has been approved for consent (October 25)and is close to finalization. This internet draft 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. Overview of Parameters to be registered The following parameters defined in ITU V.150.1 recommendation need to be registered with the IANA: 1. New MIME types: audio/v150mr and audio/v150fw. These indicate media formats defined, in the ITU V.150.1 recommendation, for use in the modem- over-IP context. MIME registration applications based on RFC 2048 [4] are in Section 4. These refer to the ITU V.150.1 recommendation for detailed format descriptions and semantics. 2. New SDP parameters (Section 3). These include a new transport protocol (udpsprt, section 3.1) and several new SDP attributes (Section 3.2). Precise details of their syntax and semantics, found in ITU recommendation V.150.1, are not repeated. Kumar et al September 2002 Page 2 IANA Registration of ITU V.150.1 MIMEs and SDP parameters 3. Registration of new SDP parameters 3.1 Registration of the 'udpsprt' transport protocol The 'udpsprt' (Simple Packet Relay Transport over UDP) protocol should be registered as a value of the SDP field "proto", referring to the transport protocol. Details of the 'udpsprt' (Simple Packet Relay Transport over UDP) protocol are found in [1]. This is a reliable protocol that can be used to efficiently guarantee packet delivery in an IP network that is prone to packet loss. 3.2 Registration of new SDP attributes New SDP attributes defined in ITU V.150.1 [1] should be registered as values of the SDP field "att-field". Details of these attributes, listed below, are found in [1]: 1. sprtparm, a list of parameters qualifying the 'udpsprt' protocol. 2. sprtmap, which dynamically defines a numerical identifier for modem relay packets. 3. vndpar (vendor parameters), used to declare vendor-specific parameters. The SDP attribute 'gpmd' (general-purpose media descriptor) is addressed elsewhere [2]. This attribute is used extensively in ITU V.150.1 systems. 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.150.1 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 "0" (ITU V.8-compatible modem relay) and "1" (universal modem relay). mg: the type of media gateway, from the set "0" (No Transcompression), "1" (Single Transcompression) and "2" (Double Transcompression. CDSCselect: Call discrimination mode selection, from the set 1 ('audio (RFC 2833)'), 2 ('VBD-preferred'), 3 (Mixed). mrmods: This parameter lists supported modulation types. These are listed as one or more comma-separated elements, where each element is either a single integer or two integers separated by a hyphen. No white space is allowed. The integers, which designate modulation Kumar et al September 2002 Page 3 IANA Registration of ITU V.150.1 MIMEs and SDP parameters 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). jmdelay: indicates support of JM delay procedures. Permissible values are "yes" and "no". Optional parameters: versn: Composite representation of the version of the ITU V.150 Recommendation used. Dotted representation, x.y, where the integer 'x' is the suffix in the number of the controlling Recommendation ('1' for ITU V.150.1), and the integer 'y' is the version of this Recommendation ('2' for the version 2 of Recommendation V.150.1). The default is fixed or configured for the Gateway or endpoint. Declaration of a value of this parameter implies backward compatibility with earlier versions (values of 'y') and document suffixes (values of 'x'). txalgs: This parameter lists supported optional transcompression algorithms. Not listed is ITU V.42bis, which is mandatory. This list consists of 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 designate transcompression algorithms are from the set "1" (ITU V.44), "2" (MNP5). If this parameter is omitted, ITU V.44 and MNP5 are not supported. V42bNumCodewords: Proposed number of ITU V.42bis code words. This is an integer in the range 512 û 65535, with a default of 1024. v42bMaxStringLength: Maximum ITU V.42bis string size, range 6-250. The default, when omitted, is 32. v44NumTxCodewords: Proposed number of ITU V.44 transmitter code words. This is an integer in the range 256 û 65535, with a default of 1024. v44NumRxCodewords: Proposed number of ITU V.44 receiver code words. This is an integer in the range 256 û 65535, with a default of 1024. v44MaxTxStringLength: Maximum ITU V.44 transmitter string size, range 32 û 255. The default, when omitted, is 64. v44MaxRxStringLength: Maximum ITU V.44 receiver string size, range 32 û 255. The default, when omitted, is 64. V44LenTxHistory: Proposed size of the V.44 transmitter history, range 512 û 65535. The default, when omitted, is 3072. V44LenRxHistory: Proposed size of the V.44 receiver history, range 512 û 65535. The default, when omitted, is 3072. TCXpreference: When two double transcompression (D-TCX) gateways are connected, this parameter indicates preference for the initial transcompression mode. Possible values are 1 ('single') and 2 ('double'), with 1 as the default. Kumar et al September 2002 Page 4 IANA Registration of ITU V.150.1 MIMEs and SDP parameters Encoding considerations: The MIME audio/v150mr uses the 'udpsprt' (Simple Packet Relay Transport over UDP) reliable transport protocol as defined in the ITU V.150.1 recommendation. As such, it consists of packets of binary data. Security considerations: The privacy and integrity of the data transmitted via V.150.1 modem relay must be ensured at the application level by means such as encryption. The V.150.1 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.150.1 modem relay are published in various standards and can be implemented by a resourceful attacker. Likewise, V.150.1 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.150.1 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.150.1 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.150.1 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, approved for consent on October 25, 2002. 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 Kumar et al September 2002 Page 5 IANA Registration of ITU V.150.1 MIMEs and SDP parameters 2. File extension(s): N/A 3. Macintosh file type code: N/A Kumar et al September 2002 Page 6 IANA Registration of ITU V.150.1 MIMEs and SDP parameters 4.2 Registration of the audio/v150fw MIME type This MIME represents the format of messages used to define the contextual framework of information transfer operation as defined in the ITU V.150.1 recommendation. Hence the suffix 'fw' (framework). MIME media type name: audio MIME subtype name: v150fw Required parameters: None. Optional parameters: events: The "events" parameter lists the framework event messages supported by the media gateway or endpoint. Events are listed as one or more comma-separated elements. Each element can either be a single integer, or two integers separated by a hyphen. The latter indicates a range of integers. No white space is allowed in the representation. The integers, which identify event types are from the set "0" (null), "1" (initial audio), "2" (voice band data), "3" (modem relay), "4" (text relay), "5" (fax relay). When omitted, the default is 0-4. expack: indicates whether explicit framework message acknowledgement procedures, as defined in the ITU V.150.1 recommendation are enabled or not. Both sides must enable these procedures in order for them to be used. Permissible values are "yes" and "no". Encoding considerations: Like all other ITU V.150.1 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.150.1 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 September 2002 Page 7 IANA Registration of ITU V.150.1 MIMEs and SDP parameters 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.150.1 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, approved for consent on October 25, 2002. 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. Security considerations for SDP parameters defined in this document are unchanged from RFC 2327 [3]. 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. Details found in ITU Recommendation V.150.1 [1] are not repeated, except as necessitated by MIME registration rules [4]. 7. Acknowledgements The ITU SG16/Q11 team led by Keith Chu, Rapporteur for the modem-over-IP question (Q11). This team includes members of the TIA TR.30.1 modem-over-IP standards group, which was chaired by Les Brown in the past and is currently chaired by Keith Chu. TIA TR.30.1 reports to the TIA TR.30 organization, which is chaired by Fred Lucas. Detailed review of and indispensable contribution towards of the ITU V.150.1 SDP definition by Flemming Andreasen, Bill Foster and Dave Oran. Kumar et al September 2002 Page 8 IANA Registration of ITU V.150.1 MIMEs and SDP parameters 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.150.1 recommendation. 8. References [1] TD-91, Proposed text for ITU V.150.1, Procedures for the end-to-end connection of V-series DCEs over an IP Network, approved for consent, Oct 25, 2002. [2] SDP attribute for qualifying Media Formats with Generic Parameters, draft-rajeshkumar-mmusic-gpmd-01.txt. [3] RFC 2327, Session Description Protocol (SDP). [4] RFC 2048, MIME registration procedures. Kumar et al September 2002 Page 9 IANA Registration of ITU V.150.1 MIMEs and SDP parameters 9. Authors' Addresses Rajesh Kumar Cisco Systems 170 West Tasman Dr San Jose, CA 95035, USA Phone: +1 408 527 0811 E-mail: rkumar@cisco.com Jim Renkel The CommWorks Corporation, a 3COM company 3800 Golf Rolling Meadows, IL 60008, USA Phone: +1 847 262 2539 E-mail: james_renkel@commworks.com Michael Nicholas The CommWorks Corporation, a 3Com Company 3800 Golf Rolling Meadows, IL 60008, USA Phone: +1 847 262 2673 E-mail: Michael_Nicholas@3com.com Fred Lucas, Chair TIA TR-30 FAL Associates 3421 Buttonwood Court Reisterstown, MD 21136-4401, USA Phone: +1 410 239 0248 E-mail: fred.lucas@ieee.org Keith Chu TIA TR-30.1 (MoIP) chair Conexant Systems 4311 Jamboree Road Newport Beach, CA 92660, USA Phone: +1 949 579 4121 E-mail: keith.chu@mindspeed.com Herb Wildfeuer Cisco Systems, Inc. 150 Castilian Drive Goleta, CA 93117, USA Phone: +1 805 961 3620 Email: hwildfeu@cisco.com Paul E. Jones Cisco Systems, Inc. 7025 Kit Creek Road RTP, NC 27709, USA Phone: +1 919 392 6948 E-mail: paulej@packetizer.com Adrian Zakrzewski Texas Instruments, Inc Kumar et al September 2002 Page 10 IANA Registration of ITU V.150.1 MIMEs and SDP parameters 20450 Century Blvd Germantown, MD 20874, USA Phone: +1 301 515 6636 E-mail: azakrzewski@ti.com Frank Chen Conexant Systems 4311 Jamboree Road Newport Beach, CA 92660, USA Phone: +1 949 579 3296 E-mail: frank.chen@mindspeed.com Mehryar Garakani Cisco Systems 150 Castilian Drive Goleta, CA 93117, USA Phone: +1 805 961 3640 E-mail: mgarakan@cisco.com Alex Urquizo Cisco Systems 1414 Massachusetts Ave. Boxborough, MA 01719, USA Phone: +1 978 936 0172 E-mail: aurquizo@cisco.com Nate Melhorn Cisco Systems 1414 Massachusetts Ave. Boxborough, MA 01719, USA Phone: +1 978 936 0144 E-mail: nmelhorn@cisco.com Ken Jones Lucent Technologies Phone: +1 603 362 5949 E-mail: kdjones1@lucent.com Daniel DeLiberato Cisco Systems 1414 Massachusetts Ave. Boxborough, MA 01719, USA Phone: +1 978 936 0111 E-mail: ddeliber@cisco.com Hisham Abdelhamid Cisco Systems 170 West Tasman Dr San Jose, CA 95035, USA Phone: +1 408 525 6940 E-mail: hisham@cisco.com Mohamed Mostafa Cisco Systems 170 West Tasman Dr San Jose, CA 95035, USA Phone: +1 408 525 2378 Kumar et al September 2002 Page 11 IANA Registration of ITU V.150.1 MIMEs and SDP parameters E-mail: mmostafa@cisco.com John Malone, LAKE Datacomms, Greenhills Rd, Dublin 24, Ireland. Phone: +353 1 403 1000 E-mail: john.malone@lakecommunications.com Other members of TIA TR.30.1 whose names have been inadvertently omitted. These will be added in a future revision. Please inform the editor of such omissions. Kumar et al September 2002 Page 12