PPP LCP Internationalization Configuration Option

Network Working Group                                            G. Zorn
Request for Comments: 2484                         Microsoft Corporation
Category: Standards Track                                   January 1999
Updates: 2284, 1994, 1570


           PPP LCP Internationalization Configuration Option

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

1.  Abstract

   The Point-to-Point Protocol (PPP) [1] provides a standard method for
   transporting multi-protocol datagrams over point-to-point links.  PPP
   also defines an extensible Link Control Protocol (LCP), which allows
   negotiation of an Authentication Protocol for authenticating its peer
   before allowing Network Layer protocols to transmit over the link.

   Both LCP and Authentication Protocol packets may contain text which
   is intended to be human-readable [2,3,4].  This document defines an
   LCP configuration option for the negotiation of character set and
   language usage, as required by RFC 2277 [5].

2.  Specification of Requirements

   In this document, the key words "MAY", "MUST, "MUST NOT", "optional",
   "recommended", "SHOULD", and "SHOULD NOT" are to be interpreted as
   described in [6].

3.  Additional LCP Configuration Option

   The Configuration Option format and basic options are already defined
   for LCP [1].

   Up-to-date values of the LCP Option Type field are specified in STD 2
   [7].  This document concerns the following value:

      28  Internationalization

   The Internationalization option described here MAY be negotiated
   independently in each direction.

   Only one instance of this option SHOULD be sent by an implementation,
   representing its preferred language and charset.

   If Internationalization option is rejected by the peer, the default
   language and charset MUST be used to construct all human-readable
   messages sent to the peer.

4.1.  Internationalization

   Description

      This Configuration Option provides a method for an implementation
      to indicate to the peer both the language in which human-readable
      messages it sends should be composed and the charset in which that
      language should be represented.

   A summary of the Internationalization option format is shown below.
   The fields are transmitted from left to right.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |          MIBenum
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             MIBenum (cont)        |        Language-Tag...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      28


   Length

      >= 7
   MIBenum

      The MIBenum field is four octets in length.  It contains a unique
      integer value identifying a charset [5,11].

      This value MUST represent one of the set of charsets listed in the
      IANA charset registry [7].

      The charset registration procedure is described in RFC 2278 [9].

      The default charset value is UTF-8 [10].  The MIBenum value for
      the UTF-8 charset is 106.

   Language-Tag

      The Language-Tag field is an ASCII string which contains a
      language tag, as defined in RFC 1766 [8].

      Language tags are in principle case-insensitive; however, since
      the capitalization of a tag does not carry any meaning,
      implementations SHOULD send only lower-case Tag fields.

      The default Tag value is "i-default" [8].

4.  References

   [1]  Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51, RFC
        1661, July 1994.

   [2]  Simpson, W., "PPP Challenge Handshake Authentication Protocol
        (CHAP)", RFC 1994, August 1996.

   [3]  Simpson, W., "PPP LCP Extensions", RFC 1570, January 1994.

   [4]  Blunk, L. and J. Vollbrecht, "PPP Extensible Authentication
        Protocol (EAP)", RFC 2284, March 1998.

   [5]  Alvestrand, H., "IETF Policy on Character Sets and Languages",
        BCP 18, RFC 2277, January 1998.

   [6]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [7]  Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC 1700,
        October 1994.  See also: http://www.iana.org/numbers.html

   [8]  Alvestrand, H., "Tags for the Identification of Languages", RFC
        1766, March 1995.

   [9]  Freed, N. and J. Postel, "IANA Charset Registration Procedures",
        BCP 19, RFC 2278, January 1998.

   [10] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
        2279, January 1998.

   [11] Smith, R., Wright, F., Hastings, T., Zilles, S. and J.
        Gyllenskog, "Printer MIB", RFC 1759, March 1995.

5.  Security Considerations

   It is possible that an attacker might manipulate the option in such a
   way that displayable messages would be unintelligible to the reader.

6.  Acknowledgements

   Thanks to Craig Fox (fox@cisco.com), James Carlson
   (carlson@ironbridgenetworks.com), Harald Alvestrand
   (Harald.Alvestrand@maxware.no), Kevin Smith (kevin@ascend.com), Karl
   Fox (karl@ascend.com), Thomas Narten (narten@raleigh.ibm.com) and
   Narendra Gidwani (nareng@microsoft.com) for helpful suggestions and
   feedback.

7.  Chair's Address

   Karl Fox
   Ascend Communications
   3518 Riverside Drive
   Suite 101
   Columbus, OH 43221

   Phone: +1 614 326 6841
   EMail: karl@ascend.com

8.  Author's Address

   Glen Zorn
   Microsoft Corporation
   One Microsoft Way
   Redmond, Washington 98052

   Phone: +1 425 703 1559
   Fax:   +1 425 936 7329
   EMail: glennz@microsoft.com

9.  Full Copyright Statement

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

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