First, today's Internet routing and multicasting protocols provide few mechanisms, if any, to protect the exchange of control information or the provision of qualities of service to user applications. By contrast, in the tactical internet, nodes and links may be compromised and routing protocols must adapt to drastic changes in link quality and connectivity much more frequently than in the quasi-static routing structure of ATM networks and the IP Internet.
Active packets can contain data, invocations to procedures, or control procedures.
Active packets that modify the behavior of nodes must be disseminated reliably and in a trusted manner among multiple nodes. The standard approach to routing in computer networks today consists of computing a single shortest path from a source to each destination using some heuristic link-cost metric, which is typically not directly associated with the transmission and queueing delays over links and paths. These two traditional approaches to routing have inherent strengths and drawbacks. However, implementing optimal dynamic routing in a computer network has simply been infeasible to date. MPDA consists of An efficient method to disseminate partial topology information, instead of flooding full topology information, and allow routers to compute shortest paths to destinations.