is based on the Control and Status Register Management (CSR) architecture, which means that all interconnected devices appear as a single memory of up to 256 Terabytes (256 X 1012 bytes). Each transmitted packet of data contains three elements: a 10-bit bus ID that is used to determine which FireWire bus the data packet originated from, a 6-bit ID that identifies which device or node on that bus sent the data packet, and a 48-bit offset that is used to address registers and memory in a node. While primarily used for inter-device communication, The Internet Society has combined IP with the FireWire standard to produce a standard Chapter Two called IP over IEEE 1394, or IP 1394. This makes it possible for networking services such as FTP, HTTP and TCP/IP to run on the high speed FireWire PHY layer as an alternative to Ethernet. An important feature of Fire Wire is that the connections are "hot-swappable", which means that a new device can be connected, or an existing device disconnected, while the connection is live. Devices are automatically assigned node IDs, and these IDs can change as the network topology changes. Combining the node ID variability of FireWire with the IP requirement for stable IP addresses of connected devices, presents one of the interesting problems in enabling IP connections over FireWire. This is solved using a special Address Resolution Protocol (ARP) called 1394 ARP. In order to uniquely identify a device in the network, 1394 ARP uses the 64-bit Extended Unique Identifier (EUI-64), a unique 64-bit number that is assigned to every FireWire device on manufacture. This is an extended version of the MAC address, described in the Section "Media Access Control, p. 21" that is used to address devices other than network interfaces. A 48-bit MAC address can be converted into a 64-bit EUI-64 by prefixing the two hexadecimal octets "FF-FF". Universal Serial Bus The Universal Serial Bus (USB) was introduced in the mid-1990s to provide a hot-swappable "plug-and-play" interface that would replace differ