Communication equipment having an available bandwidth less than 100 Mbps may be regarded as IEEE1394 communication equipment in which buses (21, 31) are connected together via a bridge (40). The bridge (40) includes portals (40A, 40B), and the portals (40A, 40B) communicate with each other through infrared rays. RAMs (43A, 43B) include bandwidth available registers for writing a remaining amount of an available bandwidth, which may be used in an isochronous communication within the bridge (40). ROMs (44A, 44B) store an available bandwidth, which may be used in a isochronous communication in respective infrared communication units (45A, 45B), as an initial value (BWR). When the bridge (40) is initialized, the initial value (BWR) is written in the bandwidth available registers. Thus, even when an available bandwidth between the infrared communication units (45A, 45B) is less than 100 Mbps, the bridge (40) may be regarded and operated as communication equipment in which the available bandwidth is 100 Mbps.