TIA/EIA-732-507:2001

Introduction

This Part of the Cellular Digital Packet Data (CDPD) System
Specification defines a protocol for the exchange of routing
and registration information between a Mobile End System (M-ES) and
a serving Mobile Data Intermediate System (MD-IS). This part was
originally known as Part 407.

This protocol is connectionless and is designed to operate in
close conjunction with protocols providing connectionless mode
network service, such as Connectionless Network Protocol
(CLNP) [ISO-8473] and Internet Protocol (IP)
[RFC-791]. It is also designed to operate in conjunction with the
Mobile Network Location Protocol (Part 501) for providing
Mobility Management services in the CDPD Network.

This protocol provides configuration information about M-ESs to
MD-ISs. An MD-IS is informed of the Network Entity Identifiers
(NEIs) supported by each M-ES and the subnetwork point of
attachment (SNPA) address of the M-ES. That is, a serving MD-IS
obtains information that allows it to associate destination network
addresses to specific channel streams and to specific data link
connections on the channel stream. Once the MD-IS obtains this
information, reachability information and routing metrics
concerning these NEIs may be disseminated to other MD-IS for the
purpose of calculating routes to/from each M-ES on the
subnetwork.

This protocol performs logically the same functions specified in
[ISO-9542]. However, the characteristics of the CDPD environment
invalidate the operation of [ISO-9542] as follows:

a. The Redirection subset of [ISO-9542] is invalidated by the
Radio Frequency (RF) subnetwork topology, which is a
point-to-multipoint star subnetwork type. All data traffic
originating from an M-ES is received by, and only by, a single
MD-IS controlling the subnetwork channel. There are no better paths
to use when forwarding Network Protocol Data Units (NPDUs) to their
destination.

b. Portions of the Configuration subset of [ISO-9542] are
invalidated by the RF subnetwork topology and presence of a single
MD-IS on the subnetwork channel to which the M-ES is attached.
Direct M-ES to M-ES communication is not possible, nor can NPDUs be
routed other than through the single MD-IS on the subnetwork.

c. It is desirable for an M-ES to be able to deregister specific
NEIs from the CDPD Network in a controlled manner.