RFC 1209 (rfc1209) - Page 2 of 11
Transmission of IP datagrams over the SMDS Service
Alternative Format: Original Text Document
RFC 1209 IP and ARP over the SMDS Service March 1991
o SHOULD or RECOMMENDED -- the item should generally be followed
for all but exceptional circumstances.
o MAY or OPTIONAL -- the item is truly optional and may be
followed or ignored according to the needs of the implementor.
Introduction
The goal of this specification is to allow compatible and
interoperable implementations for transmitting IP datagrams and ARP
requests and replies.
The characteristics of the SMDS Service and the SMDS Interface
Protocol (SIP) are presented in [3], [6], and in [7]. Briefly, the
SMDS Service is a connectionless, public, packet-switched data
service. The operation and features of the SMDS Service are similar
to those found in high-speed data networks such as LANs:
o The SMDS Service provides a datagram packet transfer, where each
data unit is handled and switched separately without the prior
establishment of a network connection.
o The SMDS Service exhibits high throughput and low delay, and
provides the transparent transport and delivery of up to 9188
octets of user information in a single transmission.
o No explicit flow control mechanisms are provided; instead, the
rate of information transfer on the access paths is controlled
both in the subscriber-to-network direction and in the network-
to-subscriber direction through the use of an access class
enforcement mechanism.
o Both individually and group-addressed (multicast) packets can
be transferred.
o In addition to these LAN-like features, a set of addressing-
related service features (source address validation, source and
destination address screening) are provided to enable a
subscriber or set of subscribers to create a logical private
network, or closed user group, over the SMDS Service. The
access control provided by the closed user group mechanism is
supplied by the SMDS provider according to the specifications
stated in [3].
o SMDS addresses are 60 bits plus a 4 bit Address Type. The
Address Type subfield occupies the 4 most significant bits of
the destination and source address fields of the SIP Level 3
Protocol Data Unit (PDU). It contains the value 1100 to
IP over SMDS Working Group