A configurable and extensible transport protocol

The ability to configure transport protocols from collections of smaller software modules allows the characteristics of the protocol to be customized for a specific application or network technology. This paper describes an approach to building such customized protocols using Cactus, a system in which micro-protocols implementing individual attributes of transport can be combined into a composite protocol that realizes the desired overall functionality. In contrast with similar systems, Cactus supports non-hierarchical module composition and event-driven execution, both of which increase flexibility and allow finer-grain modules implementing orthogonal properties. To illustrate this approach, the design and implementation of a configurable transport protocol called CTP is presented. CTP allows customization of a number of properties including reliable transmission, congestion detection and control, jitter control, and message ordering. This suite of micro-protocols has been implemented using Cactus/C 2.0 on Red Hat Linux 6.2, with initial experimental results indicating that the ability to target the guarantees more precisely to the needs of applications can in fact result in better performance.