Beyond layering: modularity considerations for protocol architectures

This paper considers ways to achieve modularity in protocol architectures without layering. Modularity promotes interoperability by making it easier to port protocol implementations; layering, on the other hand, has been identified as a performance impediment because it enforces sequential processing of messages. Focusing on end-to-end protocols, the authors propose mechanisms (metaheaders and generic interfaces) that support modular parallel or integrated protocol implementations and encourage architecture-independent specifications. An example illustrates interoperability between two systems that support the same protocols, one using traditional layering and the other supporting parallel protocol composition