Motorola Labs Mobile IPv4 specifies mechanisms that need assistance from a AAA server and a AAA infrastructure. Examples of such mechanisms are those providing key management and authentication services during a registration process of the mobile node with MN-AAA authentication extension. Although Diameter Mobile IP application is being specified to support the needs of Mobile IPv4 from the point of view of the AAA infrastructure, such support does not exist within RADIUS framework. This document defines the RADIUS attributes that provide support for Mobile IPv4 operation.