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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MMUSIC G. Salgueiro 3 Internet-Draft Cisco Systems 4 Intended status: Standards Track April 20, 2011 5 Expires: October 22, 2011 7 The 'image' Media Type for the Session Description Protocol (SDP) 8 draft-gsalguei-image-media-type-00 10 Abstract 12 This document describes the registration of 'image' as a top-level 13 media type for the Session Description Protocol (SDP). The 'image' 14 media type is primarily used by SDP to negotiate and establish T.38 15 media streams. 17 Status of this Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at http://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on October 22, 2011. 34 Copyright Notice 36 Copyright (c) 2011 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (http://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Conventions Used in This Document . . . . . . . . . . . . . . . 3 52 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3 54 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 55 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 56 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 57 6.1. Normative References . . . . . . . . . . . . . . . . . . . 5 58 6.2. Informative References . . . . . . . . . . . . . . . . . . 6 59 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 61 1. Conventions Used in This Document 63 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 64 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 65 document are to be interpreted as described in [RFC2119]. 67 2. Overview 69 In the previous version of the SDP specification [RFC2327] packetized 70 media types, such as those shared by RTP, share the same namespace 71 used by the Multipurpose Internet Mail Extensions (MIME) media types 72 registry [RFC2048] (i.e. "MIME types"). This is in contrast to the 73 latest version of the SDP specification [RFC4566] where an SDP- 74 specific media type registry is created. The top-level SDP media 75 content types registered by [RFC4566] are "audio", "video", "text", 76 "application", and "message". A glaring omission on this list is the 77 'image' media type. 79 The 'image' media type is an existing top-level MIME type and is 80 widely used by SDP for setting up T.38 Real-Time Facsimile [T38] 81 media streams. This media type is extensively referenced by examples 82 in ITU-T T.38 [T38] and IETF standards like [RFC4145]. 84 This document complies with the request of section 8.2.1 of [RFC4566] 85 that indicates: 87 "The same rules should apply for media names as for top-level 88 media content types, and where possible the same name should be 89 registered for SDP as for MIME. For media other than existing 90 top-level media content types, a Standards Track RFC MUST be 91 produced for a new top-level content type to be registered, and 92 the registration MUST provide good justification why no existing 93 media name is appropriate." 95 The registration of 'image' as a top-level SDP media type ensures 96 seamless continuity with documentation that uses the 'image' MIME 97 type. This also simplifies the usage of previously registered MIME 98 sub-types like 'image/t38' [RFC3362] that are used as SDP media 99 descriptors for T.38 [T38]. 101 3. IANA Considerations 103 This document registers with IANA the 'image' media type as a top- 104 level media content type in accordance with the "Standards Action" 105 policy defined in Section 4.1 of [RFC5226]. This registration 106 follows the procedures described in BCP 13 [RFC4288]. 108 To: ietf-types@iana.org 110 Subject: Registration of 'image' media type for the Session 111 Description Protocol (SDP) 113 Type name: image 115 Subtype name: 117 Required parameters: None 119 Optional parameters: None 121 Encoding considerations: 122 Binary encoding as defined in ITU-T Recommendation T.38 [T38]. 124 Security considerations: 125 Refer to Section 4 127 Interoperability considerations: 128 This media type is primarily intended to be utilized as a 129 parameter by SDP [RFC4566] in SIP [RFC3261] to establish T.38 130 [T38] media streams. 132 Published specification: RFC 4566 134 Applications that use this media type: 135 Real-time facsimile (fax) 137 Additional information: 139 Magic number(s): 140 File extension(s): 141 Macintosh file type code(s): 143 Person & email address to contact for further information: 145 Gonzalo Salgueiro 146 gsalguei@cisco.com 148 Intended usage: COMMON 150 Restrictions on usage: None 151 Author: 152 Gonzalo Salgueiro 154 Change controller: 155 The IESG 157 4. Security Considerations 159 The 'image' media type registered by this document to the IANA 160 registry for SDP [SDP-IANA] is primarily for use by the offer/answer 161 model of the Session Description Protocol [RFC4566] for the 162 negotiation and establishment of T.38 [T38] media streams using the 163 Session Initiation Protocol [RFC3261]. This additional SDP parameter 164 does not introduce any new security considerations beyond those 165 detailed in Section 7 of [RFC4566]. The security vulnerabilities in 166 T.38 [T38] and its associated transport protocols (TCP [RFC0793], UDP 167 [RFC0768], or RTP [RFC3550]) are well documented in each of their 168 respective specifications. 170 5. Acknowledgements 172 Thanks goes to the chairs of the IETF Multiparty Multimedia Session 173 Control (MMUSIC) working group (Miguel A. Garcia and Flemming 174 Andreasen) for their guidance, encouragement, and the creation of the 175 media type registry. 177 The author would also like to acknowledge the considerable efforts of 178 Kevin Fleming and the members of the FoIP TG in the SIP Forum that 179 contributed to the new revision of the ITU-T T.38 Recommendation that 180 prompted the need to register the 'image' media type for SDP. 182 6. References 184 6.1. Normative References 186 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 187 Requirement Levels", BCP 14, RFC 2119, March 1997. 189 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 190 Description Protocol", RFC 4566, July 2006. 192 [SDP-IANA] 193 IANA, "Session Description Protocol (SDP) Parameters", 194 http://www.iana.org/assignments/sdp-parameters , 2011. 196 6.2. Informative References 198 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 199 August 1980. 201 [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, 202 RFC 793, September 1981. 204 [RFC2048] Freed, N., Klensin, J., and J. Postel, "Multipurpose 205 Internet Mail Extensions (MIME) Part Four: Registration 206 Procedures", BCP 13, RFC 2048, November 1996. 208 [RFC2327] Handley, M. and V. Jacobson, "SDP: Session Description 209 Protocol", RFC 2327, April 1998. 211 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 212 A., Peterson, J., Sparks, R., Handley, M., and E. 213 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 214 June 2002. 216 [RFC3362] Parsons, G., "Real-time Facsimile (T.38) - image/t38 MIME 217 Sub-type Registration", RFC 3362, August 2002. 219 [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. 220 Jacobson, "RTP: A Transport Protocol for Real-Time 221 Applications", STD 64, RFC 3550, July 2003. 223 [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in 224 the Session Description Protocol (SDP)", RFC 4145, 225 September 2005. 227 [RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and 228 Registration Procedures", BCP 13, RFC 4288, December 2005. 230 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 231 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 232 May 2008. 234 [T38] International Telecommunications Union, "Procedures for 235 real-time Group 3 facsimile communication over IP 236 Networks", ITU-T Recommendation T.38, 2010. 238 Author's Address 240 Gonzalo Salgueiro 241 Cisco Systems 242 7200-12 Kit Creek Road 243 Research Triangle Park, NC 27709 244 US 246 Email: gsalguei@cisco.com