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1、 CEA Standard Generic Common Application Language Quality of Service ANSI/CEA-721.4 February 1998 Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:15 MDTNo reproduction or networkin
2、g permitted without license from IHS -,-,- NOTICE 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 products, and assisting
3、 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 conforming to s
4、uch 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. Standards, Bulletin
5、s 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, Bulletin or oth
6、er 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. This Standard do
7、es 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 before its use. (Fr
8、om Project Number 4570, formulated under the cognizance of the CEA R7 Home Networks Committee.) Published by CONSUMER ELECTRONICS ASSOCIATION 2002 Technology & Standards Department 2500 Wilson Boulevard Arlington, VA 22201 PRICE: Please call Global Engineering Documents, USA and Canada (1-800-854-71
9、79) International (303-397-7956), or http:/ All rights reserved Printed in U.S.A. Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:15 MDTNo reproduction or networking permitted with
10、out license from IHS -,-,- PLEASE! DON”T VIOLATE THE LAW! This document is copyrighted by CEA and may not be reproduced without permission. Organizations may obtain permission to reproduce a limited number of copies through entering into a license agreement. For information, contact: Global Engineer
11、ing Documents 15 Inverness Way East Englewood, CO 80112-5704 or call U.S.A. and Canada 1-800-854-7179, International (303) 397-7956 See http:/ or email Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resa
12、le, 03/30/2007 20:58:15 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:15 MDTNo reproduction or networkin
13、g permitted without license from IHS -,-,- CEA-721.4 (Formerly Titled EIA-721.4) Generic Common Application Language (Generic CAL) Specification This document is Part 4, the Generic CAL Quality-of-Service portion of EIA-721. Issued: EIA-721.4, 11-24-97 Copyright Consumer Electronics Association Prov
14、ided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:15 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employe
15、es/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:15 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-721.4 Generic Common Application Language Quality of Service Issued: EIA-721.4, 11-24-97 i Contents 1. INTRODUCTION.1 1.1 Quality-of-Service (QOS) .1 1.2
16、 Model of a Generic Network.1 2. NETWORK ADDRESSING.3 2.1 EHS Addressing3 2.2 EIA-600 Standard Addressing.3 2.3 EIB Group Addressing4 3. THE DISCOVERY PROCESS.4 3.1 Setting QOS Parameters4 3.2 Reading QOS Parameters5 4. QUALITY OF SERVICE PARAMETERS5 4.1 Layer 6 - Presentation5 4.2 Layer 5 - Session
17、.6 4.3 Layer 4 - Transport6 4.3.1 Message Segmentation.6 4.3.2 Error Management7 4.3.3 Layer 4 QOS Variables 7 4.4 Layer 3 - Network Layer .7 4.4.1 Flood versus Directory Routing.8 4.4.2 Allowed Media and Brouters .8 4.4.3 Network Layer QOS Parameters9 4.5 Layer 2 - Data Link Layer .10 4.5.1 Acknowl
18、edgments10 4.5.2 Include Source Address11 4.5.3 Packet Priority11 4.5.4 Service Class 11 4.5.5 Layer 3 QOS Parameters12 4.6 Device Addressing 13 4.7 Timing Parameters 13 5. SUMMARY OF RECOMMENDED QOS PARAMETERS.14 Copyright Consumer Electronics Association Provided by IHS under license with CEA Lice
19、nsee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:15 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not fo
20、r Resale, 03/30/2007 20:58:15 MDTNo reproduction or networking permitted without license from IHS -,-,- EIA-721.4 Generic Common Application Language Quality of Service Specification 1. Introduction 1.1 Quality-of-Service (QOS) The specification for Generic CAL consists of an Application Layer conta
21、ining a command language and a Message Transfer Service Element. The specifications of the lower OSI layers are not within the scope of this standard. However, the services provided by the lower layers affect the performance and composition of messages issued from the Application Layer. These lower
22、layer service options are collectively called the Quality-of-Service (QOS) available from the communications protocol. This portion of the EIA-721 standard describes those lower layer QOS options that may impact the Application Layer. Recommended capabilities are specified. Also, a mechanism to conv
23、ey these options to the Generic CAL Application Layer using Layer System Management functions is presented. 1.2 Model of a Generic Network A Generic Network is any communications protocol implementation that includes Generic CAL and the associated Application Layer functions. The functions of the Ge
24、neric Network protocol are expected to be implemented in modules that enable devices to be connected to a local area network adapted for premises automation applications. Figure 1 illustrates the connection of devices to a shared-medium network. The Network Interface is responsible for translating b
25、etween device-specific messages and signals on the network using the Generic Network protocol. Network Medium Device Controller Device #1Device #2 Network Interface Network Interface Network Interface Device #3 Device Controller Device Controller Figure 1. A Common Network Interface for Devices Shar
26、ing a Communications Medium Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:15 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-721.4 Generic Common Ap
27、plication Language Quality of Service 2 The EIA-721 standard is based on the assumption that devices using Generic CAL should be able to be adapted easily for operation on multiple networks. Ideally, adaptation means changing one internal module, integrated circuit, and/or software. Devices may inte
28、roperate across different networks via a gateway. The objective is to allow manufacturers to provide one set of procedures (routines) for Generic CAL in a device, independent of the network. The Generic CAL messages and the Application Layer service calls need to adapt to the lower-layer QOS options
29、 statically or dynamically. Static adaptation implies that the interface module is designed for a specific Generic Network. Dynamic Adaptation allows the interface module to be self- configuring. A Discovery Process is specified for setting internal module parameters when the device is configured au
30、tomatically for a new network. Network X Medium Device Controller Generic CAL Network X Interface Device #1 Generic CAL Network X Interface Device #2 Generic CAL Network X Interface Device #3 Network Y Medium Generic CAL Network Y Interface Device #1 Generic CAL Network Y Interface Device #2 Generic
31、 CAL Network Y Interface Device #3 Device Controller Device Controller Device Controller Device Controller Device Controller Figure 2. Adapting Products to a Generic Network Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing
32、, Bernie Not for Resale, 03/30/2007 20:58:15 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-721.4 Generic Common Application Language Quality of Service Issued: EIA-721.4, 11-24-97 3 Figure 2 shows the benefits of the Generic Network model of EIA-721. The Generic CAL m
33、odule can be independent of the target stack, while the network interface module is specialized for a particular network. Whether a device is designed for Network X or Network Y of Figure 2, the device controller and Generic CAL module can be the same. Only a different network interface module is ne
34、cessary. During a configuration process, the Generic CAL module might query the network interface module, discover the QOS parameters, and adjust the Application Layer accordingly. 2. Network Addressing To accommodate device operation on a variety of Generic Networks with simple adaptation, a standa
35、rdized addressing scheme is desired. In practice, one addressing methodology across multiple networks is not feasible and might limit or unnecessarily burden some networks. In EIA-721.1, addressing is specified as either short format of fixed length or long format with a length of three to eight 16-
36、bit words. The specific addressing scheme for a Generic Network is determined by the lower OSI layers. In a Generic Network, an Adaptation Layer may be interposed between the Application Layer and the lower Generic Network layers. An Adaptation Layer might translate Generic CAL application addresses
37、 to formats that correspond to various network features. Two diverse examples of addressing are described in the next subsections. 2.1 EHS Addressing EHS is the European Home Systems specification for a home automation communications network. EHS was developed by a consortium of European companies a
38、s a project of the European Commission. In the EHS protocol each application process is identified by an application address. An address directory function maps application addresses to corresponding subunit and network addresses. An EHS physical device consists of one or more units, which may conta
39、in individually addressable components, each with a unique subunit address. A mapping service is provided both for the local source address and for the remote destination address. This mapping directory is part of the Application Title Directory (ATD), which contains additional data about each subun
40、it. EHS mapping from an application address to a network address and a destination subunit address facilitates product interoperability. This is especially important for networks that assign network addresses dynamically or change addresses when a device is moved. In these cases, the mapping directo
41、ry would need to be updated. A practical issue is the RAM required for a mapping table. 2.2 EIA-600 Standard Addressing Addresses at the Application Layer in the EIA-600 standard are identical to the Data Link Layer addresses. Thus, no address translation is required. Such addresses are known as MAC
42、 Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:15 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-721.4 Generic Common Application Language Quality
43、of Service 4 addresses, where MAC is the Medium Access Control Sublayer of the Data Link Layer. This scheme is feasible because MAC addresses in the EIA-600 standard are independent of device location on the network. 2.3 EIB Group Addressing EIB (European Installation Bus) is a communications protoc
44、ol developed for facilitating home and building automation. It defines a hierarchical bus to replace dedicated wires for linking sensors, actuators, controllers, and control panels. These components are organized into systems that provide services such as lighting, security, and HVAC (Heating, Venti
45、lating, and Air-conditioning). Devices in an EIB network contain physical addresses that are related to the location of each device on the network. One or more logical addresses are assigned to a device for message transmission. These addresses represent communications objects, such as temperature s
46、et-point or light-level. Messages are exchanged among communications objects in EIB. An EIB message is generated as the result of an event: a significant change of state or value within a communications object. Messages may include unspecified application data in addition to event parameters. EIB su
47、pports group addressing of communications objects. For example, several light fixtures may be grouped together and switched from one (or several) switches. When grouped, the communications objects are assigned a group address. One or more 16-bit group addresses can be assigned to a device function.
48、There are no restrictions on group address assignment. This free assignment facility accommodates a large number of identical elements, such as switches, luminaires, and temperature sensors that must be individually addressed for a flexible system design. 3. The Discovery Process The Discovery Process is a procedure whereby Generic CAL determines the QOS paramete