IPP> Time-related DHCP options

IPP> Time-related DHCP options

Ira McDonald imcdonal at sdsp.mc.xerox.com
Thu May 27 10:18:51 EDT 1999


Hi folks,                                        Wednesday (26 May 1999)

I did some research on time-related BOOTP/DHCP options.  I also found
the interesting (but poorly documented) DHCP option 100 'Printer Name'.
The relevant RFCs for BOOTP and DHCP are listed at the end of this note.

Cheers,
- Ira McDonald

----------
'ftp://ftp.isi.edu/in-notes/std-index.txt'

0012 Network Time Protocol. D. Mills. September 1989. (Format: TXT=193
     bytes) (Also RFC1119)

0026 Time Server Protocol. J. Postel. May 1983. (Format: TXT=3024
     bytes) (Also RFC0868)

----------
'ftp://ftp.isi.edu/in-notes/iana/assignments/bootp-dhcp-extensions'
in 'bootp-dhcp-option-100':

To: iana at ISI.EDU
Subject: Re[2]: Information about DHCP Options
Date: Mon, 30 Dec 1996 15:29:34 -0500
From: Harry_Hans_at_PO-SIGNAL at ZEUS.SIGNALCORP.COM (Harry Hans)
     
   Printer Name Option:
   
   This option specifies a list of names for printers on the client's 
   subnet.  The printers may or may not be up and running.  Printer
   names should be listed in order of preference.
   
   The code for this option is 100, and its minimum length is 1.
   
   
      code    length          Printer Name
   -----------------------------------------------------
   |        |       |      |      |      |      |
   | 100    |  n    |  h1  |  h2  |  h3  |  h4  | ...........
   |        |       |      |      |      |      |
   -----------------------------------------------------

----------
'ftp://ftp.isi.edu/in-notes/iana/assignments/bootp-dhcp-parameters'

   Tag     Name          Data Length    Meaning          
   ---     ----          -----------    -------          
     2     Time Offset       4          Time Offset in Seconds from UTC
     4     Time Server       N          N/4 Timeserver addresses
    42     NTP Servers       N          NTP Server Addresses
    88     IEEE 1003.1 POSIX N          IEEE 1003.1 POSIX Timezone
   100     Printer Name      N          Printer Name

----------
'ftp://ftp.isi.edu/in-notes/rfc2132.txt' page 6:

3.4. Time Offset

   The time offset field specifies the offset of the client's subnet in
   seconds from Coordinated Universal Time (UTC).  The offset is
   expressed as a two's complement 32-bit integer.  A positive offset
   indicates a location east of the zero meridian and a negative offset
   indicates a location west of the zero meridian.

   The code for the time offset option is 2, and its length is 4 octets.

    Code   Len        Time Offset
   +-----+-----+-----+-----+-----+-----+
   |  2  |  4  |  n1 |  n2 |  n3 |  n4 |
   +-----+-----+-----+-----+-----+-----+

----------
'ftp://ftp.isi.edu/in-notes/rfc2132.txt' page 6:

3.6. Time Server Option

   The time server option specifies a list of RFC 868 [6] time servers
   available to the client.  Servers SHOULD be listed in order of
   preference.

   The code for the time server option is 4.  The minimum length for
   this option is 4 octets, and the length MUST always be a multiple of
   4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   |  4  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

----------
'ftp://ftp.isi.edu/in-notes/rfc2132.txt' page 18:

8.3. Network Time Protocol Servers Option

   This option specifies a list of IP addresses indicating NTP [18]
   servers available to the client.  Servers SHOULD be listed in order
   of preference.

   The code for this option is 42.  Its minimum length is 4, and the
   length MUST be a multiple of 4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   |  42 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

----------
'ftp://ftp.isi.edu/in-notes/iana/assignments/bootp-dhcp-extensions'
in 'bootp-dhcp-option-88':

From: mwc at atlantic.sun.com
Date: Wed, 30 Oct 1996 15:17:59 -0500 (EST)
Subject: Request for DHCP option code
To: iana at ISI.EDU

Hi,
    I requesting an option code for the following working doc.

Thank you,
Mike  Carney
Sun Microsystems, Inc.


Network Working Group                                       M. W. Carney
INTERNET-DRAFT                                    Sun Microsystems, Inc.
                                                           November 1996

            DHCP Option for IEEE 1003.1 POSIX Timezone Specifications

[snip...]

Abstract

   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].

Introduction

   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.

   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 specifier

   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.

              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:

   EST5EDT4,116/02:00:00,298/02:00:00

References

   [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 at East.Sun.COM

------------------------------------------------------------------------
                        Time Service RFCs
           'ftp://ftp.isi.edu/in-notes/rfc-index.txt':

0868 Time Protocol. J. Postel, K. Harrenstien. May-01-1983. (Format:
     TXT=3140 bytes) (Also STD0026) (Status: STANDARD)

1119 Network Time Protocol (Version 2) specification and implementation.
     D.L. Mills. Sep-01-1989. (Format: TXT=143, PS=518020
     bytes) (Obsoletes RFC0958, RFC1059) (Obsoleted by RFC1305) (Also
     STD0012) (Status: STANDARD)

1305 Network Time Protocol (Version 3) Specification, Implementation.
     David L. Mills. March 1992. (Format: TXT=307085 bytes) (Obsoletes
     RFC0958, RFC1059, RFC1119) (Status: DRAFT STANDARD)

------------------------------------------------------------------------
                      BOOTP and DHCP RFCs
           'ftp://ftp.isi.edu/in-notes/rfc-index.txt':

0951 Bootstrap Protocol. W.J. Croft, J. Gilmore. Sep-01-1985. (Format:
     TXT=28354 bytes) (Updated by RFC1395, RFC1497, RFC1532, RFC1542)
     (Status: UNKNOWN)

1542 Clarifications and Extensions for the Bootstrap Protocol. W.
     Wimer. October 1993. (Format: TXT=52948 bytes) (Obsoletes RFC1532)
     (Updates RFC0951) (Status: DRAFT STANDARD)

2131 Dynamic Host Configuration Protocol. R. Droms. March 1997.
     (Format: TXT=113738 bytes) (Obsoletes RFC1541) (Status: DRAFT
     STANDARD)

2132 DHCP Options and BOOTP Vendor Extensions. S. Alexander, R. Droms.
     March 1997. (Format: TXT=63670 bytes) (Obsoletes RFC1533) (Status:
     DRAFT STANDARD)

2489 Procedure for Defining New DHCP Options. R. Droms. January 1999.
     (Format: TXT=10484 bytes) (Also BCP0029) (Status: BEST CURRENT
     PRACTICE)

------------------------------------------------------------------------




More information about the Ipp mailing list