AMTP: Towards a High Performance and Configurable Multipeer Transfer Service

Abstract

This paper presents the service specification and an excerpt of a performance analysis of the Adaptive Multicast Transfer Protocol (AMTP) focusing on different error handling strategies for multicast communication scenarios. The need for sophisticated and dedicated multicast mechanisms to be provided by transfer protocols (covering protocols of layers 3 and 4 according to the ISO/OSI Reference Model) in order to support group communication becomes evident in the light of the versatile QOS (Quality of Service) requirements imposed by multimedia applications and the broad service spectrum offered by different network architectures. Today’s protocols provide neither the required range of functionality nor the necessary performance.

Although various transport protocols are capable of providing some basic functionality essential for multicast applications, they do not address requirements for different delivery semantics, real-time support or dynamic group membership. However, AMTP is a first step in bridging the services gap by offering an application driven error control, mechanisms to reduce the acknowledgement implosion, support for different grades of reliability, guarantees for different QOS requirements, etc. in addition to usual transport layer protocol features. The configurability and feature richness of AMTP results from the call/connection principle, which splits a multimedia call into different media dependent connections, and a novel service concept, which subdivides the services allocated to a specific connection into primary and secondary ones.