The 1394.1 functionality

The IEEE 1394 standard [3,4], specifies how devices, identified by their 64-bit hardware addresses, can be interconnected with cables, without users having to worry about configuring these devices. The IEEE abstraction as presented in the standard consists of nodes, identified by 6-bit physical ids, connected with a serial bus. This abstraction is illustrated in Figure 1.

Figure 1: An example IEEE 1394 serial bus

In order to meet its high-performance needs, IEEE 1394 restricts serial buses to a maximum of 63 nodes attached, with a maximal cable length of 4.5 meters between each pair of nodes. Larger networks may be built by connecting serial buses with bridges which selectively route network traffic originating from a node on one bus destined to a node on another bus. The IEEE 1394.1 standard [5] specifies how buses can be interconnected with bridges, consisting of a pair of directly coupled nodes called bridge portals, without users having to worry about configuring any of these buses. The two portals which constitute one bridge, called each other's co-portal, communicate via the bridge fabric, a medium which is beyond the 1394 protocol. It is important to note that as a consequence, each of the two co-portals resides on its own separate bus. The abstraction as presented in the standard consists of a net of serial buses, where each bus is identified by a 10-bit bus id. This abstraction is illustrated in Figure 2. The main restriction on IEEE 1394.1 nets is the maximum of 1023 buses attached.

Figure 2: An example IEEE 1394.1 net