RFC 1395 (rfc1395) - Page 2 of 8

BOOTP Vendor Information Extensions

RFC 1395                    BOOTP Extensions                January 1993


   Bootstrap Protocol (BOOTP) is a UDP/IP-based protocol that allows a
   booting host to configure itself dynamically, and more significantly,
   without user supervision.  It provides a means to assign a host its
   IP address, a file from which to download a boot program from some
   server, that server's address, and (if present) the address of an
   Internet gateway.

   One obvious advantage of this procedure is the centralized management
   of network addresses, which eliminates the need for per-host unique
   configuration files.  In an environment with several hundred hosts,
   maintaining local configuration information and operating system
   versions specific to each host might otherwise become chaotic.  By
   categorizing hosts into classes and maintaining configuration
   information and boot programs for each class, the complexity of this
   chore may be reduced in magnitude.

BOOTP Vendor Information Format

   The full description of the BOOTP request/reply packet format may be
   found in [RFC-951].  The rest of this document will concern itself
   with the last field of the packet, a 64 octet area reserved for
   vendor information, to be used in a hitherto unspecified fashion.  A
   generalized use of this area for giving information useful to a wide
   class of machines, operating systems, and configurations follows.  In
   situations where a single BOOTP server is to be used among
   heterogeneous clients in a single site, a generic class of data may
   be used.

   Vendor Information "Magic Cookie"

      As suggested in [RFC-951], the first four bytes of this field have
      been assigned to the magic cookie, which identifies the mode in
      which the succeeding data is to be interpreted.  The value of the
      magic cookie is the 4 octet dotted decimal 99.130.83.99 (or
      hexadecimal number 63.82.53.63) in network byte order.

   Format of Individual Fields

      The vendor information field has been implemented as a free
      format, with extendable tagged sub-fields.  These sub-fields are
      length tagged (with exceptions; see below), allowing clients not
      implementing certain types to correctly skip fields they cannot
      interpret.  Lengths are exclusive of the tag and length octets;
      all multi-byte quantities are in network byte-order.







Reynolds