The electronics industry has entered the era of multi-million-gate chips, and there Xs no turning back. This technology promises new levels of integration on a single chip, called the System-on-a-Chip (SoC) design, but also presents significant challenges to the chip designer. Processing cores on a single chip, may number well into the high tens within the next decade, given the current rate of advancements, [1]. Interconnection networks in such an environment are, therefore, becoming more and more important [2]. Currently on-chip interconnection networks are mostly implemented using buses. For SoC applications, design reuse becomes easier if standard internal connection buses are used for interconnecting components of the design. Design teams developing modules intended for future reuse can design interfaces for the standard bus around their particular modules. This allows future designers to slot the reuse module into their new design simply, which is also based around the same standard bus [3]. In this paper we give an overview of the more popular on-chip bus-based interconnection networks such as AMBA, Avalon CoreConnect, STBus, Wishbone, etc. The main characteristics of the considered buses in respect to topology, arbitration method, bus-width, and types of data transfers are discussed.