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1、 CEA Standard IP-Based Digital Telephony for the Versatile Home Network CEA-851.1-A February 2009 Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=HP Monitoring/1111111164 Not for Resale, 04/08/2009 01:31:17 MDTNo reproduction or networking permitted without
2、 license from IHS -,-,- NOTICE Consumer Electronics Association (CEA) Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of product
3、s, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards, Bulletins and other technical publications shall not in any respect preclude any member or nonmember of CEA from manufacturing or selling products not
4、 conforming to such Standards, Bulletins or other technical publications, nor shall the existence of such Standards, Bulletins and other technical publications preclude their voluntary use by those other than CEA members, whether the standard is to be used either domestically or internationally. Sta
5、ndards, Bulletins and other technical publications are adopted by CEA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, CEA does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Standard,
6、 Bulletin or other technical publication. This CEA Standard is considered to have International Standardization implication, but the International Electrotechnical Commission activity has not progressed to the point where a valid comparison between the CEA Standard and the IEC document can be made.
7、This Standard does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations bef
8、ore its use. (Formulated under the cognizance of the CEAs R7 Home Network Committee.) Published by CONSUMER ELECTRONICS ASSOCIATION 2009 Technology however, we leave discussion of implementing non-IP telephony on the VHN to a later version of this Standard. We note first that, as the VHN is an IP-ba
9、sed internet, it is capable of transporting any IP traffic, regardless of the interpretation of the packet contents. Thus, IP-based telephony transport is “native” to the VHN, and the VHN is transparent to the transport of “telephony” packets. However, as with other services that may be provided usi
10、ng the VHN, control signals for IP telephony require some attention. In addition, as telephony usually implies connectivity to a public telephone network outside the home, it will be necessary for the IP telephony end device (which may not be a traditional telephone set) to have a logical interface
11、with software that will probably reside on an access-backbone interface or an access-component interface, such as a Residential Gateway or a cable modem. While it is beyond the scope of this Standard to specify the architecture or operation of these devices, we feel it is important to require the pr
12、esence of certain software on the access interfaces. Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=HP Monitoring/1111111164 Not for Resale, 04/08/2009 01:31:17 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-851.1-A 3 2. GENE
13、RAL 2.1 Scope This standard addresses IP-based digital telephony (sometimes referred to as “Voice over IP”) on the VHN. As the VHN is inherently digital it does not address analog telephony; nor does it address non-packet digital telephony, such as the streaming service provided by ISDN. However, fu
14、ture versions of this standard may address non- IP telephony. Although this Standard has been issued as a separate document, it is an integral part of CEA-851, “VHN Home Network Specification.” Requirements and specifications in CEA-851 also implicitly apply to the functions and devices described in
15、 this Standard, unless there specifically stated otherwise. Also, note that this Standard defines the requirements for implementing a telephony function on a VHN. As such, it is not a device description. Any VHN device that implements telephony is also expected to implement all other parts of CEA-85
16、1 that are applicable and appropriate for such a device. For example, CEA-851 requires that a VHN device support a web server; thus, any device implementing the telephony function, as described in this Standard, would be expected to include a web server that would conform to the requirements in CEA-
17、851. 2.2 Normative References The following standards contain provisions that, through reference in this text, constitute normative provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on th
18、is standard are encouraged to investigate the possibility of applying the most recent editions of the standards listed in Sec. 2.2.1. If the referenced standard is dated, the reader is advised to use the version specified. 2.2.1 Normative Reference List: 1. CEA-851, “VHN Home Network Specification,”
19、 October 2000. 2. IETF RFC 2543, “SIP: Session Initiation Protocol,” March 1999. 2.2.2 Normative Reference Acquisition: CEA standards can be ordered from Global Engineering Documents, http:/ IETF RFCs may be downloaded from http:/www.rfc-editor.org/. 2.3 Informative References The following document
20、s contain information that is useful in understanding this standard. Some of these documents are drafts of standards that may become normative references in a future release of this standard. Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=HP Monitoring/111
21、1111164 Not for Resale, 04/08/2009 01:31:17 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-851.1-A 4 2.3.1 Informative Document List: 3. ITU-T Recommendation H.323, “Packet-based multimedia communication systems”. 4. IETF RFC 1889, “RTP: A Transport Protocol for Real-T
22、ime Applications,” January 1996. 2.3.2 Informative Document Acquisition: ITU-T International Telecommunications Union, Place des Nations, CH-1211 Geneva 20, Switzerland; Phone +41 22 730 5111; Fax +41 22 733 7256; Internet http:/www.itu.ch/publications/bookstore.html; Email itumailitu.int. IETF IETF
23、 RFCs may be downloaded from http:/www.rfc-editor.org/. 2.4 Symbols and Abbreviations IETF Internet Engineering Task Force ISDN Integrated Services Digital Network ITU International Telecommunications Union POTS Plain Old Telephone Service RTP Real-time Transport Protocol SIP Service Initiation Prot
24、ocol SONET Synchronous Optical Network VHN Versatile Home Network 2.5 Compliance Notation As used in this document, “shall” and “must” denote a mandatory provisions of the standard. “Should” denotes a provision that is recommended but not mandatory. “May” denotes a feature whose presence does not pr
25、eclude compliance that may or may not be present at the option of the implementer. “Optional” denotes items that may or may not be present in a compliant DTV. Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=HP Monitoring/1111111164 Not for Resale, 04/08/200
26、9 01:31:17 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-851.1-A 5 3. IP-based Digital Telephony IP-based telephony in the VHN, as described in Annex A, is affected by implementation of the following requirements: 1. All telephony end devices on the VHN shall implemen
27、t the SIP 2 protocol, known heretofore as a “SIP stack.” 2. All telephony control signals and all packets, including signals that are inherently isochronous, such as voice or video, or other telephony user traffic shall be carried only as asynchronous packets on the IEEE 1394b backbone and on IEEE 1
28、394a component networks of the VHN. As the SIP protocol assumes asynchronous service, use of the IEEE 1394 isochronous service for IP-based digital telephony is not supported in this Standard; if a user prefers to implement telephony on the IEEE 1394 isochronous channels, it is the responsibility of
29、 the user to define the interfaces between asynchronous services and the IEEE 1394 isochronous stream, as well to manage IP telephony as an IEEE 1394 isochronous service (i.e. to define allocation of bandwidth, channel numbers, and applications that control user access to telephony services). 3. If
30、a VHN implements IP telephony within the home, it shall host the required SIP software, including a SIP proxy server, on a networked device. 4. Connection to the public telephone network is effected through an access-backbone interface or an access-component interface. Note that the internal archite
31、cture of such devices is outside the scope of this Standard; nevertheless, we require that if such a device is connected to the VHN to effect an IP telephony connection to the public telephone network, that device shall host a SIP proxy server, and any other SIP software necessary to realize an IP t
32、elephony connection to the public telephone network. 5. These specifications require modifications to the VHN Protocol Stack (Figure 6 in CEA-851 1). These changes are reflected in the revised Protocol Stack Figure 1 below. Copyright Consumer Electronics Association Provided by IHS under license wit
33、h CEA Licensee=HP Monitoring/1111111164 Not for Resale, 04/08/2009 01:31:17 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-851.1-A 6 SIP Other Other IEEE 1394 Physical Layer IEEE 1394 Link Layer 1394 Serial Bus Mgmt. (Config ROM, CSR) 1394 Transaction Layer Asynchronou
34、s IPv4 Unicast over 1394 FCP IEC61883-1 MPEG-2 TS (Single Program TS) 1394 Node Discovery MPEG-2 PES MPEG-2 PSI RT MPEG A/V ES CMP IEC61883-1 AV/C AV/C App ATSC PSIP Isoch. Data Flow Mgmt IPv4 Mcast over 1394 TCP UDP HTTP OMG UNO RPC DSM-C C SNMP VHN Exchange (XML Messaging) VHN Object Model Layer (
35、CAL,AV/C) MPEG-2 Section Other Data Other Isoch. formats DV, DSS Real Time Data Transmission Protocol (IEC 618833-1-6) OMG IDL DSM-CC Private Section DSM-CC Object Carousel ARP IP IPv4 Bcast over 1394 BER Optional Mandatory Figure 1 Revised VHN Protocol Stack (replaces Figure 6 in CEA-851) Copyright
36、 Consumer Electronics Association Provided by IHS under license with CEA Licensee=HP Monitoring/1111111164 Not for Resale, 04/08/2009 01:31:17 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-851.1-A 7 ANNEX A: IP-Based Telephony (Informative) A.1 Introduction In this se
37、ction we address the implementation of IP-based digital telephony on the VHN. Note that digital telephony does not require the use of the Internet Protocol suite1; however, we leave discussion of implementing non-IP telephony on the VHN to a later version of this Standard. We first note that, as the
38、 VHN is an IP-based internet, it is capable of transporting any IP traffic, regardless of the interpretation of the packet contents. Thus, IP-based telephony transport is “native” to the VHN, and the VHN is transparent to the transport of “telephony” packets. However, as with many other services tha
39、t may be provided over the VHN, control signals for IP telephony require some attention. In addition, as telephony usually implies connectivity to a public telephone network outside the home, it will be necessary for the IP telephony end device (which may not be a traditional telephone set) to have
40、a logical interface with software that will probably reside on an access-backbone interface or an access-component interface, such as a Residential Gateway or a cable modem. While it is beyond the scope of this Standard to specify the architecture or operation of these devices, we feel it is importa
41、nt to require the presence of certain software on the access interfaces. A.2 Assumptions We begin by stating some assumptions underlying the telephony specifications in this Standard: A.2.1 Digital Telephony (not POTS) As the VHN is a digital network, we assume that specifications for telephony excl
42、ude analog systems, such as “Plain Old Telephone Service” (POTS). At this time, almost all telephony is analog, but the presence of digital telephony is expected to grow over the next several years. For the transition period between analog and digital telephone systems it is suggested that digital s
43、ystems have “friendly” codec(s) for existing analog devices such as fax/modem devices. We confine our discussion to the integration of these emerging digital telephony technologies into the VHN. 1 For instance, ISDN uses synchronous streams that are circuit-switched, rather than packet-switched. Cop
44、yright Consumer Electronics Association Provided by IHS under license with CEA Licensee=HP Monitoring/1111111164 Not for Resale, 04/08/2009 01:31:17 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-851.1-A 8 A.2.2 Packet-based Telephony (not ISDN) Furthermore, as mention
45、ed above, not all digital telephony is packet-based, let alone IP- based. In particular, ISDN (Integrated Services Digital Network) uses a streaming, synchronized digital signal, similar to other traditional digital telephony transport signals, such as T1 and SONET. While ISDN has had some recent po
46、pularity for implementing Internet connections to the home (and, in fact, most digital telephony at this time uses ISDN), it is expected that ISDN will give way to packet-based systems within a few years. Thus, we confine ourselves, in this version of the Standard, to packet-based telephony. If ISDN
47、 proves to be more resilient and long-lived than we have assumed, a future version of this Standard may include provisions for implementing ISDN on the VHN. A.2.3 All telephony traffic will be asynchronous on IEEE 1394 busses Digital telephony may be used to carry the full range of digital signals,
48、from traditional voice telecommunications, to asynchronous data, to video. However, because we assume digital telephony is IP-based; all telephony signals will be carried as asynchronous packets on the IEEE 1394b backbone of the VHN, including signals that are inherently isochronous, such as voice or video. At present, almost all packet-based digital telephony end devices are equipped with Ethernet connections, and it is assumed that this choice of component network will continue in the future; however, there is nothing to prevent a manufac