GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc3054

Network Working Group P. Blatherwick (Editor) Request for Comments: 3054 Nortel Networks Category: Informational R. Bell

                                                         Cisco Systems
                                                            P. Holland
                                                  Circa Communications
                                                 (Chair TIA TR-41.3.4)
                                                          January 2001
         Megaco IP Phone Media Gateway Application Profile

Status of this Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

 This document specifies a particular application of the Megaco/H.248
 Protocol for control of Internet telephones and similar appliances:
 the Megaco IP Phone Media Gateway.  The telephone itself is a Media
 Gateway (MG), controlled by the Megaco/H.248 Protocol, with
 application control intelligence located in the Media Gateway
 Controller (MGC).  To achieve a high degree of interoperability and
 design efficiency in such end-user devices, a consistent
 architectural approach, a particular organization of Terminations and
 Packages, and a Protocol Profile are described.  The approach makes
 use of existing Protocol features and user interface related
 Packages, and is thus a straight-forward application of the
 Megaco/H.248 Protocol.

1. Introduction

 This document represents the current view from the TIA working group
 on VoIP (Voice over IP) telephone specification [1], TIA TR-41.3.4,
 with the intent of using this as part of its "whole device"
 specification as an optional method of device control.
 Industry feedback has made it clear that interoperability and
 acoustic performance of Internet telephones is key to the rapid and
 extensive commercialization of these products.  To facilitate this,
 the TIA has established working group TR-41.3.4 to develop a standard

Blatherwick, et al. Informational [Page 1] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

 for VoIP telephones.  The TR-41.3.4 working group has included the
 "whole device" within the scope of the standard, so a full range of
 requirements including acoustic performance, protocols, methods for
 powering and safety are provided.  Where possible, the requirements
 are based on existing standards, which are included by reference.
 The TIA TR-41.3.4 working group has also recognized that its proposed
 standard must enable creative application of the equipment, encourage
 the development of new capabilities and allow for high levels of
 product customization.  To achieve this, peer to peer architectures
 that are based on protocols such as H.323 or SIP and master/slave
 architectures such as Megaco/H.248 Protocol are both necessary and
 complementary.
 In support of the Megaco/H.248 Protocol development effort, the TR-
 41.3.4 working group has considered product enabling issues and
 requirements, and has developed an approach to use the Megaco/H.248
 Protocol for Internet telephone device control.  This document
 represents the working group's current view.
 This document covers the general requirements of the Megaco IP Phone
 application (section 3), architectural approach and MG organization
 (section 4), details of specific Termination types used and Packages
 supported by each (section 5), and the Megaco IP Phone Protocol
 Profile (section 6).

2. Conventions

 The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
 SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
 document, are to be interpreted as described in RFC 2119 [5].

3. General Requirements

 The following general requirements were identified to drive the
 Megaco IP Phone design [1]:
 1. The Megaco IP Phone must meet the basic needs of the business user
    from day one;
 2. Provide a path for rapid expansion to support sophisticated
    business telephony features;
 3. Flexibility to allow for a very wide range of telephones and
    similar devices to be defined, from very simple to very feature
    rich;
 4. Simple, minimal design;

Blatherwick, et al. Informational [Page 2] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

 5. Allow device cost to be appropriate to capabilities provided;
 6. Packages and Termination types must have characteristics that
    enable reliability;
 7. The IP Phone MG shall meet the appropriate Megaco/H.248 Protocol
    requirements as provided in the Megaco Requirements document [2]
    and be a straight-forward application of the Megaco/H.248 Protocol
    [3].

4. Architecture Description

 The following subsections describe the general design approach and
 organization of the Megaco IP Phone MG.

4.1. Design Approach

 Design intent of the Megaco IP Phone is to keep it determinedly
 simple while providing required support for fully featured business
 telephones and the flexibility to allow for a very wide range of
 telephone configurations and similar appliances.
 The approach to achieve this goal is to provide a very simple and
 direct master/slave control model in which very little feature
 intelligence is required in the end device.  This design intent
 matches the Megaco/H.248 Protocol approach well.
 It is important to note that additional functionality, built-in
 feature capability or system-specific optimization can easily be
 provided, at the option of the implementer, by defining additional
 Termination types, Event/Signal Packages, or providing built-in
 application capability.  This document defines the minimal design
 only.

4.2. General Structure

 As shown in Figure 1 below, the Megaco IP Phone is organized as a
 Media Gateway (MG) that consists of a User Interface Termination and
 a set of Audio Transducer Terminations.
 Several - potentially thousands - of Megaco IP Phone MGs may be
 controlled by a single Media Gateway Controller (MGC).  This is
 distinguished from the organization between traditional analog or PBX
 telephones behind an IP network, where the MGC would control an MG
 which in turn controls the collection of telephone devices in
 question.  In the case of a Megaco IP Phone MG, the MG directly

Blatherwick, et al. Informational [Page 3] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

 implements the media terminations like handset, handsfree and
 headset, as well as the user interface.  In this case, the Megaco IP
 Phone itself is the MG.
                           +---------------+
                           |               |
                           |      MGC      |
                           |               |
                           +---------------+
                                   ^ \ \ \
                                   |
                                   v
             +---------------------------------------------+
             |                                             |
             |   Megaco IP Phone MG                        |
             |   ==================      Audio Transducer  |
             |                           Terminations:     |
             | Audio context(s):         + - - - - - - - + |
             | +---------------------+     +-----------+   |
             | |     Context A       |   | | Handset   | | |
             | |                     |     +-----------+   |
        RTP  | |  +-----+   +-----+  |   | +-----------+ | |
    <--------+-+->| Tr  |   | Ta2 |<-+-----| Handsfree |   |
      audio  | |  +-----+   +-----+  |   | +-----------+ | |
     stream  | |                     |     +-----------+   |
             | +---------------------+   | | Headset   | | |
             |                             +-----------+   |
             |                           |               | |
             |                              ETC.           |
             |                           + - - - - - - - + |
             |                                             |
             |  +----------------------------------------+ |
             |  | User Interface Termination             | |
             |  | +--------------+      +--------------+ | |
             |  | | Text Display |      | Keypad       | | |
             |  | +--------------+      +--------------+ | |
             |  | +--------------+      +--------------+ | |
             |  | | Softkeys     |      | Indicators   | | |
             |  | +--------------+      +--------------+ | |
             |  | +--------------+                       | |
             |  | | Function Keys|       ETC.            | |
             |  | +--------------+                       | |
             |  +----------------------------------------+ |
             +---------------------------------------------+
           Figure 1: Megaco IP Phone Termination / Package Model

Blatherwick, et al. Informational [Page 4] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

4.3. Termination / Package Organization

 As shown in Figure 1, each Audio Transducer Termination represents an
 individually controllable audio input/output element of the telephone
 device, such as Handset, Handsfree, Headset, etc.  By separating each
 audio element as a distinct Termination, more flexible applications
 can be easily implemented, such as paging, group listening, and so
 on. Since this is actually only the logical view of the device,
 represented by protocol, it is also quite possible to simplify
 representation of the device by hiding all available audio
 input/outputs behind a single Audio Transducer Termination, for
 example the Handset, and implement control of multiple real
 input/outputs locally inside the device.
 All non-audio user interface elements are associated with the User
 Interface Termination.  This special Termination supports Packages to
 implement all user interaction with the telephone user interface,
 including Function Keys, Indicators, the Dialpad, etc, as appropriate
 for the specific device capabilities (within constraints given in the
 section on User Interface Termination).  The User Interface
 Termination cannot be placed in any Context.  This grouping of user
 interface elements behind a well-know Termination greatly simplifies
 audits to determine actual device configuration, and reduces the
 number of Terminations involved in representing user interface.
 In addition, TerminationID naming conventions are provided to
 identify specific Terminations within the Megaco IP Phone MG and
 group them into related sets.  These conventions use a set of well
 known identifier names to specify the individual Terminations, for
 example the User Interface Termination ("ui"), the Handset Audio
 Transducer ("at/hs"), or the Handsfree Audio Transducer ("at/hf").
 This specific naming is important in this application, especially for
 the Audio Transducer Terminations, since the real input/output
 elements to which they map on the physical device have very different
 functional significance to the end-user, yet they may be represented
 in the protocol using exactly the same sets of Packages.  Naming
 conventions allow the controlling MGC to distinguish this end-user
 meaning without specific advance knowledge of physical device
 configuration and without the requirement to provide different
 Packages for each audio input/output type.
 Using these same TerminationID naming conventions in combination with
 wildcards, the MGC application can target commands to groups of
 related Terminations, for example the collection of all Audio
 Transducer Terminations ("at/*").  This is especially useful during
 the discover phase, for example to efficiently Audit all available
 Audio Transducer Terminations, and to efficiently send commands to a
 set of related Terminations in a single command, for example to

Blatherwick, et al. Informational [Page 5] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

 simultaneously Subtract all Audio Transducer Terminations from a
 particular Context.  Further information on TerminationID naming
 conventions and their use can be found under the sections on Control
 Interaction and Capability Discovery (next two subsections) and under
 Termination Types.

4.4. Control Interaction

 To provide control of audio paths, Audio Transducer Terminations are
 manipulated using Contexts in the normal way, by sending Add, Move,
 Subtract and Modify commands addressed to the specific Terminations
 being manipulated.  For example creating a Context (Context A)
 containing an RTP Termination (Tr) and a Handset Audio Transducer
 Termination (Ta1) creates a voice connection to/from the handset.
 Moving a Handsfree Audio Transducer Termination (Ta2) into the
 Context, and removing the Handset, sets up a handsfree conversation.
 This situation is shown in Figure 1.  See the section on Audio
 Transducer Termination Types for further details on specific Package
 support requirements.
 User input elements, such as Keypad or Function Keys, generate Events
 through Notify commands sent from the User Interface Termination of
 the Megaco IP Phone MG to the controlling MGC for handling.  These
 Events are according to the specific set of Packages supported by the
 User Interface Termination of the device.  See the section on User
 Interface Termination Type for further details on specific Package
 support requirements.
 User output elements such as the Text Display or Indicators are
 controlled by Signals sent by the MGC, addressed to the User
 Interface Termination of the Megaco IP Phone MG, generally as part of
 a Modify command, using syntax defined in the corresponding Packages.
 Since the User Interface Termination cannot be part of any context,
 Add, Move and Subtract commands sent to it are not valid.  See the
 section on User Interface Termination Type for further details on
 specific Package support requirements.
 Some elements, for example Softkeys, have both user input and output
 aspects, so both react to Signals and generate Events as above.
 The TerminationID naming conventions may be used to target commands
 to specific Terminations by well known name, for example to Add the
 Handsfree Audio Transducer Termination ("at/hf") to a Context.  The
 naming conventions in combination with wildcards may be used to
 efficiently send commands to groups of related Terminations, for
 example to simultaneously Subtract all Audio Transducer Terminations
 ("at/*") from a particular Context.

Blatherwick, et al. Informational [Page 6] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

4.5. Capability Discovery

 At startup or service change, the Megaco IP Phone MG identifies
 itself to its controlling MGC as being a Megaco IP Phone class of
 device by use of the IPPhone Protocol Profile.  This is the first and
 most important stage of capability discovery, and implicitly provides
 a great deal of the necessary information in a single step.
 Thereafter, the MGC can make a large number of assumptions regarding
 organization and behavior of the MG.  See the section on IPPhone
 Protocol Profile for further details of ServiceChange operation.
 Device capabilities, including the list of all Terminations and
 supported Packages for each, are queried through the AuditValue
 command.  Wildcarded AuditValue commands targeted at the whole MG
 (i.e., addressed to ContextID=Null, TerminationID=ALL) return the
 list of all Terminations, including the User Interface Termination
 and all supported Audio Transducer Terminations.  Since the returned
 TerminationIDs use well known identifier names, the MGC can derive
 the specific audio input/output elements available on the physical
 device, and their intended purpose.  Further AuditValues commands on
 individual named Terminations provide further details of each, for
 example for the MGC to query user interface support Packages
 available on the User Interface Termination ("ui").  TerminationID
 naming conventions in combination with wildcards can be used with
 AuditValues commands to query specific Package support for the
 collection of all Audio Transducer Terminations ("at/*").
 Since the structure of the Megaco IP Phone MG is well known in
 advance, by virtue of the IPPhone Protocol Profile, audits can be
 efficiently directed at discovering only what additional information
 is required by the MGC.  Thus the MGC is able to efficiently and
 unambiguously discover both the specific user interface capabilities
 and the supported audio input/outputs of the Megaco IP Phone MG,
 without specific advance knowledge of physical device configuration.
 It is not necessary for the MGC to attempt to infer function from
 supported Packages within a random collection of Terminations, and a
 great deal of behavior common to all Megaco IP Phone MGs can simply
 be assumed.  This pre-determined organization and behavior therefore
 greatly reduces design complexity of both MG and MGC, and greatly
 improves interoperability.

5. Termination Types

 The Termination types defined for use in the Megaco IP Phone MG are:
  • User Interface (implements user interface);

Blatherwick, et al. Informational [Page 7] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

  • Audio Transducer (implements audio input/output to the user, and

potentially appears as several individual Terminations

    corresponding to individual audio input/outputs on the physical
    device);
  • RTP (transport of audio streams over IP).
 These Termination types represent minimal capabilities to support
 fully featured business telephones.  Additional Termination types can
 be defined to extend these capabilities.
 The following subsections describe requirements and constraints on
 each type in further detail.

5.1. User Interface Termination Type

 The User Interface Termination represents the Megaco IP Phone MG user
 interface elements.  Megaco IP Phone MGs MUST support exactly one
 User Interface Termination.
 TerminationID of the User Interface Termination MUST be "ui", used
 for both command addressing and command response return.  ABNF text
 encoding for this MUST be as described in Megaco/H.248 Protocol
 Appendix B.1 [3].
 Note: If ASN.1 binary encoding is used (OPTIONAL in this
 specification), TerminationID for the User Interface Termination MUST
 be encoded as described in Megaco/H.248 Protocol Appendix A.1 [3],
 with alphabetic characters of the identifier given above mapping to
 the equivalent octet string in the ASN.1 encoding.
 The User Interface Termination cannot be part of any context, hence
 Add, Move and Subtract commands are invalid for this Termination.
 The User Interface Termination MAY support the following Packages,
 defined in Megaco/H.248 Protocol H.248 Annex G: "User Interface
 Elements and Actions Packages" [4].

Blatherwick, et al. Informational [Page 8] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

     __________________________________________________________
    | Package           | Name   | Support in User Interface   |
    |                   |        | Termination                 |
    |___________________|_______ |_____________________________|
    | Text Display      | dis    | OPTIONAL                    |
    | Keypad            | kp     | OPTIONAL                    |
    | Function Key      | kf     | OPTIONAL                    |
    | Indicator         | ind    | OPTIONAL                    |
    | Softkey           | ks     | OPTIONAL                    |
    | Ancillary Input   | anci   | OPTIONAL                    |
    |___________________|________|_____________________________|
 Additional Packages not listed above MAY also be provided where these
 are defined to extend to additional user interface elements.
 Note: The reasoning to make all Packages optional in the User
 Interface Termination is to allow maximum flexibility to create a
 very broad range of Internet telephones and similar devices.  For
 example, anything from a simple hotel lobby phone (handset and
 hookswitch only), to conferencing units (handsfree unit and one or
 two buttons) to fully featured business telephones (display, rich set
 of keys and indicators, both handset and handsfree, etc) could be
 designed.

5.2. Audio Transducer Termination Types

 The Audio Transducer Terminations are used to control audio
 input/output to/from the end user of the device.  Megaco IP Phone MGs
 MUST support at least one Audio Transducer Termination, which MAY be
 chosen from the following well known types (with identifier name):
  • Handset ("hs") – input/output,
  • Handsfree ("hf") – input/output,
  • Headset ("ht") – input/output,
  • Microphone ("mi") – input only,
  • Speaker ("sp") – output only.
 TerminationIDs of the Audio Transducer Terminations MUST be of the
 form "at/<name>", where <name> is the 2 character identifier listed
 above, used for both command addressing and command response return.
 If more than one Audio Transducer Termination of a particular type is
 implemented, the TerminationIDs of each MUST be of the form
 "at/<name>/<num>", where <num> is a 2 digit index number in
 hexadecimal format beginning at 01.  Examples of valid TerminationIDs
 include: "at/hs" (handset), "at/mi/02" (microphone 2), "at/*" (all
 audio input/outputs).  ABNF text encoding for this MUST be as
 described in Megaco/H.248 Protocol Appendix B.1 [3].

Blatherwick, et al. Informational [Page 9] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

 Note: If ASN.1 binary encoding is used (OPTIONAL in this
 specification), TerminationIDs and wildcards MUST be encoded as
 described in Megaco/H.248 Protocol Appendix A.1 [3], with alphabetic
 characters of the identifiers given above mapping to octet sub-
 strings in the ASN.1 encoding and the '/' character not used.
 Additional Audio Transducer Termination types MAY also be defined by
 the implementer, however well know identifier names for these are
 outside the scope of this specification.
 All Audio Transducer type Terminations MUST support the following
 Packages, defined in Megaco/H.248 Protocol Annex E [3].
     ____________________________________________________________
    | Package             | Name   | Support in Audio Transducer |
    |                     |        | Terminations                |
    |_____________________|_______ |_____________________________|
    | Basic DTMF Generator| dg     | REQUIRED                    |
    | Call Progress Tones | cg     | REQUIRED                    |
    |   Generator         |        |                             |
    |_____________________|________|_____________________________|
 Additional Packages not listed above MAY also be provided where
 applicable to audio input/output functions.

5.3. RTP Termination Type

 Megaco IP Phone MGs MUST support at least one RTP Termination in
 order to support audio streams to/from the device, as defined in
 Megaco/H.248 Protocol Annex E.12 [3].
 No special TerminationID naming convention is defined for RTP
 Terminations as part of this specification.

6. IPPhone Protocol Profile

 The following subsections provide details of the IPPhone Protocol
 Profile, used between Megaco IP Phone MGs and their controlling MGCs.
 This includes implicit application-level agreements between the
 Megaco IP Phone MG and its controlling MGC on organization and
 behavior of the MG, types of Terminations used and the specific
 minimum Package support for each, and specific minimum selections on
 the transport and encoding methods used.
 Use of a this Profile greatly simplifies assumptions necessary by the
 MGC regarding MG organization, thereby reducing complexity and cost
 of both MG and MGC, and improves interoperability for the specific
 Megaco IP Phone application.  Since the Profile is specific to the

Blatherwick, et al. Informational [Page 10] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

 Megaco IP Phone MG, no other applications of Megaco/H.248 Protocol
 are affected.
 It is important to note that the IPPhone Profile specifies minimum
 functionality only, for interoperability purposes.  Additional
 Termination types, Package support, transport or encoding methods, or
 other capabilities MAY be added at the discretion of the implementer
 within the general structure described.

6.1. Profile Descriptor and Usage

 Profile name: "IPPhone"
 Version: 1
 The Megaco/H.248 Protocol [3] describes startup and service change
 procedures in detail, including use of Profiles.
 In brief, the above Profile name and version are supplied by the
 Megaco IP Phone MG on startup or at service change, in the
 ServiceChangeDescriptor parameter of the ServiceChange command,
 issued to the controlling MGC as part of the registration procedure.
 In response, the MGC may 1) accept control by acknowledging the
 Service Change, 2) pass control to a different MGC by replying with a
 new MGC to try, or 3) refuse control entirely by rejecting the
 Service Change.  If MGC control is refused, the Megaco IP Phone MG
 may attempt registration with other MGCs in its list of MGCs to try.
 Once a controlling MGC accepts the IPPhone Profile, both it and the
 Megaco IP Phone MG become bound by the Profile rules and constraints
 described in subsequent subsections as well as Megaco IP Phone
 Termination/Package organization and behavior rules described in
 previous sections of this document.  Thereafter, any protocol use
 outside these rules is considered an error.

6.2 Termination Organization and Package Support

 Termination organization, required Termination types, and the
 specific Packages supported by each MUST be as described in sections
 4 - 5 of this document.
 Note that additional Termination types and Package support MAY also
 be provided within the general structure described.

6.3. Transport

 Megaco IP Phone MGs MUST support Application Layer Framing (ALF) over
 UDP transport, as specified in the Megaco/H.248 Protocol Appendix D.1
 [3].

Blatherwick, et al. Informational [Page 11] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

 Note that this does not imply that the Megaco IP Phone MG cannot
 support other transport methods as well.  TCP transport is OPTIONAL,
 but if used MUST conform to Megaco/H.248 Protocol Appendix D.2 [3].

6.4. Message Encoding

 Megaco IP Phone MGs MUST support ABNF text encoding of the protocol,
 as specified in the Megaco/H.248 Protocol Appendix B [3].
 Note that this does not imply that the Megaco IP Phone MG cannot
 support ASN.1 binary encoding as well.  ASN.1 binary encoding is
 OPTIONAL, but if used MUST conform to Megaco/H.248 Protocol Appendix
 A [3].

7. Security Considerations

 The Megaco IP Phone Media Gateway Application Profile adds no new
 security issues beyond those endemic to all applications of
 Megaco/H.248 Protocol [3].

8. References

 [1] TIA/EIA, IS-811, Performance and Interoperability Requirements
     for Voice-over-IP (VoIP) Feature Telephones,
     http://www.tiaonline.org/standards/ip/voip/tia-eia-is-811-
     final.pdf
 [2] Greene, N., Ramalho, M. and B. Rosen, "Media Gateway Control
     Protocol Architecture and Requirements", RFC 2805, April 2000.
 [3] Cuervo, F., Greene, N., Rayhan, A., Huitema, C., Rosen, B. and J.
     Segers, "Megaco Protocol Version 1.0", RFC 3015, November 2000.
 [4] ITU-T SG16, H.248 Annex G: User Interface Elements and Actions
     Packages, Brown, M. & P. Blatherwick, November 2000.
     http://www.itu.int/itudoc/itu-t/rec/h/h248anxg.html
 [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement
     Levels", BCP 14, RFC 2119, March 1997.

Blatherwick, et al. Informational [Page 12] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

9. Authors' Addresses

 Peter Blatherwick (Editor)
 Nortel Networks
 P.O. Box 3511, Stn C
 Ottawa, Ontario,
 Canada K1Y 4H7
 Phone: (613) 763-7539
        (613) 724-4726
 EMail: blather@nortelnetworks.com
        peter.blatherwick@home.com
 Bob Bell
 Cisco Systems Inc.
 576 S. Brentwood Ln.
 Bountiful, UT 84010
 USA
 Phone: (801) 294-3034
 EMail: rtbell@cisco.com
 Phil Holland
 Circa Communications Ltd.
 1000 West 14th Street
 North Vancouver, British Columbia,
 Canada V7P 3P3
 Phone: (604) 924-1742
 EMail: phil.holland@circa.ca

Blatherwick, et al. Informational [Page 13] RFC 3054 Megaco IP Phone Media GW Application Profile January 2001

10. Full Copyright Statement

 Copyright (C) The Internet Society (2001).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Blatherwick, et al. Informational [Page 14]

/data/webs/external/dokuwiki/data/pages/rfc/rfc3054.txt · Last modified: 2001/01/29 20:10 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki