IPv4 Option for Sender Directed Multi-Destination Delivery
RFC 1770

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Network Working Group                                           C. Graff
Request for Comments: 1770                                 US Army CECOM
Category: Informational                                       March 1995

       IPv4 Option for Sender Directed Multi-Destination Delivery

Status of this Memo

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

Abstract

   This memo defines an IPv4 option to provide a sender directed multi-
   destination delivery mechanism called Selective Directed Broadcast
   Mode (SDBM).  The SDBM provides unreliable UDP delivery to a set of
   IP addresses included in the option field of an IPv4 datagram.  Data
   reliability if required will be provided by the application layer.
   This approach was developed to support sender directed multi-
   destination delivery to sparsely populated groups with no additional
   control traffic.  This approach will find application in the
   extremely bandwidth constrained tactical military environment, as
   well as in some commercial applications requiring sender control of
   data delivery.

Background

   The Selective Directed Broadcast Mode (SDBM) is an integral part of
   the U.S. Army standard for tactical data communication networks as
   defined in MIL-STD-188-220() (Reference 1). The MIL-STD-188-220()
   defines a protocol architecture for the lower four layers of the
   ISO-OSI Reference model. The MIL-STD-188-220() is currently
   undergoing a reformatting to be consistent with other DoD standards
   that deal with IP networking. These efforts will provide tactical IP
   internetting of tactical Army broadcast radio networks, and will
   support fully IP compliant internetworking to other types of IP
   networks via commercial IP routers.  It is the goal of the U.S. Army
   to move toward a fully IP compliant internetwork architecture for all
   tactical battlefield data communications. The Army does, however,
   have a critical need for a reliable, sender directed multi-
   destination data transfer capability that is not currently supported
   by the existing or emerging internet standards. The SDBM IP option
   was developed to meet this need. The required data reliability will
   be provided by incorporating an acknowledgement strategy at the
   application layer. It is hoped that this IP option, providing multi-
   destination capability not currently provided by the current and

Graff                                                           [Page 1]
RFC 1770         Selective Directed Broadcast Protocol        March 1995

   emerging internet standards, will be embraced by the internet
   community and become an integal part of the IP family of protocols
   and be incorporated in commercial IP software products.

SDBM Format

   The SDBM provides the ability for an application to explicitly list a
   set of intended IP destinations. This capability will be implemented
   as an option in the IP layer, as shown in Figure 1. This option field
   is variable in length, up to a maximum of 40 octets due to the
   limitation of the HLEN field as specified in STD 5, RFC 791
   (Reference 2). Under this option 38 of the 40 octets would be used to
   contain the 2 octet control field and a maximum of 9 IP addresses.

       1            8           16                      31

       ***************************************************
       |            |            |                       |
       |            |            |                       |
       |  TYPE      |   LENGTH   |     IP ADDRESS 1      |
       |            |            |                       |
       |            |            |                       |
       |*************************************************|
       |                         |                       |
       |  IP ADDRESS 1(Cont)     |     IP ADDRESS 2      |
       |                         |                       |
       |                         |                       |
       |*************************************************|
       |                         |                       |
       |  IP ADDRESS 2(Cont)     |     ..........        |
       |                         |                       |
       |                         |                       |
       |*************************************************|
       |                         |                       |
       |                         |                       |
       |      ..........         |     IP ADDRESS N      |
       |                         |                       |
       |                         |                       |
       |*************************************************|
       |                         |                       |
       |    IP ADDRESS N(Cont)   |        UNUSED         |
       |                         |                       |
       |                         |                       |