Abstract. Due to new emerging areas in the communication field there is a constant need for the design of novel communication protocols. This demands techniques for a rapid and efficient protocol design and development. Systematic protocol designs using formal description techniques (FDTs), such as SDL, LOTOS, etc., have proven a successful way to develop correct protocols. FDTs enforce, however, a semantic-oriented description which makes it difficult to reuse parts of the specification of other FDTs. A general-purpose modeling language like the UML may help to easily bridge between different description techniques. In contrast to the standardized FDTs, UML lacks a formal semantics. A modeldriven protocol design, which aims at supporting the reuse of designs, makes only sense, when the designs of basic protocol mechanisms fit in reusable design patterns or components with a formally defined semantics. In this paper, we propose a component based protocol development approach with UML. ...