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Versions: 00 01 02 03                                                   
Nov 21 15:35 1996       POSIX Timezone Option   Carney           Page 1

Network Working Group                                       M. W. Carney
INTERNET-DRAFT                                    Sun Microsystems, Inc.
draft-ietf-dhc-timezone-00.txt                             November 1996
                                                        Expires May 1997

            DHCP Option for IEEE 1003.1 POSIX Timezone Specifications

Status of this Memo

   This document is an Internet-Draft.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas
   and its working groups.  Note that other groups may also distribute
   working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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   ftp.isi.edu (US West Coast).


   The Dynamic Host Configuration Protocol (DHCP) [1] provides a
   framework for passing configuration information to hosts on a TCP/IP
   network. This document defines a new option to extend the available
   option codes [3].


   DHCP includes an option for the specification of the Universal
   Coordinated Time Offset [2], which is defined as a two's complement
   32-bit integer representing the offset in seconds from UCT.
   Unfortunately, the UCT offset option does not provide enough
   information for an Internet client to determine such timezone-related
   details as the timezone names, daylight savings time start and end
   times in addition to the timezone UCT offsets.

Nov 21 15:35 1996       POSIX Timezone Option   Carney           Page 2

   This document defines a new option which addresses these
   shortcomings by delivering timezone information in the form of a
   1003.1 POSIX Timezone specifier [4].

Definition of option 88, IEEE 1003.1 POSIX Timezone

   This NVT ASCII string represents the IEEE 1003.1 POSIX Timezone
   specification that a client is to use to set its timezone. The
   option code number is 88.

    Code   Len    POSIX Timezone string
   | 88  |  n  |  a1 |  a2 | a3  |  a4 | ...

   The format of the IEEE 1003.1 POSIX timezone specification is
   defined as follows:

   stdoffset[dst[offset],[start[/time],end[/time]]], where:

   std, dst:  three or more bytes for the standard timezone (std) and
              daylight savings timezone (dst). If dst is missing, then
              daylight savings time does not apply in this locale. Any
              characters (or case) except a leading colon, digits,
              comma, minus or plus sign are allowed.

   offset:    Indicates the value one must add to local time to arrive
              at UCT, of the form: hh[:mm[:ss]]. offset following std
              is required. If no offset follows dst, then dst is
              assumed to be one hour ahead of standard time. Digits
              always interpreted as decimal number.

   hour:      0-23, minutes and seconds: 0-59. If preceded by a '-',
              the timezone is east of the Prime Meridian, otherwise
              it is west ('+' is optional)

   start/time,end/time: Indicate when to change to and back from
              daylight savings time. The 'time' field indicates when,
              in local time, the change is made.

              start, end:

              Jn:     The julian day n, (1 <= n <= 365). Leap days
                      not counted.

Nov 21 15:35 1996       POSIX Timezone Option   Carney           Page 3

              n:      zero-based julian day, (0 <= n <= 365). Leap
                      days are counted so it is possible to refer to
                      Feb 29.

              Mm.n.d: The 'd'th day, (0 <= d <= 6) of week 'n' of
                      month 'm' of the year (1 <= n <= 5, 1 <= m <= 12,
                      where week 5 means last 'd' day in month 'm'
                      which may occur in either the fourth or the fifth
                      week. Week '1' is the first week in which the 'd'
                      day occurs.

              time:   time has the same format as offset, except that
                      no leading '-' or '+' is permitted. The default
                      is 02:00:00.

An Example
   Eastern USA time zone, 1986:



   [1] Droms, R., "Dynamic Host Configuration Protocol", RFC 1541,
       Bucknell University, October 1993.

   [2] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
       Extensions", RFC 1533, Lachman Associates, October 1993.

   [3] Droms, R., "Procedure for Defining New DHCP Options", Work in
       progress, February, 1996.

   [4] IEEE, "1003.1 POSIX Timezone Specification", 1988.

Security Considerations

   Security issues are not discussed in this document.

Author's Address

   Mike Carney
   Sun Microsystems, Inc.
   2 Elizabeth Drive
   Chelmsford, MA 01824

   Phone: (508) 442-0469
   EMail: Mike.Carney@East.Sun.COM