ABSTRACT
Different communication networks can be interconnected through specific devices called intermediate systems (ISs). These devices have different structure, functionality, and complexity, according to the layer of the Open Systems Interconnection (OSI) reference model they refer to. This chapter describes some practical implementations of ISs, along with their features and related issues. It focuses on some of the most relevant aspects concerning the hybrid networks. After a general analysis of hybrid wired/wireless configurations and the related issues, the ways in which wireless extensions can be effectively implemented for both fieldbuses and real-time Ethernet (RTE) networks are described. The availability of the logical link control (LLC) protocol for IEEE 802.15.4 networks could enable, in principle, the implementation of extensions to RTE networks right at the data-link layer, since most networks provide access to such a layer as well. The chapter shows an example of interconnection taking place through a bridge for the hybrid networks.
