FireWire (IEEE 1394)

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Definition of FireWire in the Network Encyclopedia.

What is FireWire?

Also known as the IEEE 1394 High-Performance Serial Bus, FireWire is a serial transmission specification proposed by Apple for connecting high-speed peripherals to computers at speeds of up to 393 Mbps.

FireWire Port (IEEE 1394 Port)
FireWire Port

FireWire supports hot-swapping of peripherals with up to 63 peripherals connected to a single IEEE 1394 bus. In addition, up to 1023 IEEE 1394 buses can be interconnected to form a vast array of peripherals using FireWire.

FireWire features simple plug-in connectors using thin serial cables that can be hot-plugged without interfering with your system’s operation. FireWire connectors are based on the Nintendo Game Boy connector.

The copper cable it uses in its most common implementation can be up to 15 ft long. Power is also carried over this cable, allowing devices with moderate power requirements to operate without a separate power supply. FireWire is also available in Cat 5 and optical fiber versions.

The 1394 interface is comparable to USB. USB was developed subsequently and gained a much greater market share. USB also requires a master controller, but FireWire is managed cooperatively by the connected devices.

How it works

FireWire, as defined in IEEE 1394, uses 64-bit device addresses. FireWire cables use two twisted-pair wires for data transmission and two wires for power.

FireWire includes two different serial interfaces:

  • A backplane interface: Runs at speeds between 12.5 and 50 Mbps for bus connections within a computer system.
  • A point-to-point interface: Runs at speeds of 98.304 Mbps (S100 specification), 196.608 Mbps (S200), and 393.216 Mbps (S400) for connecting devices to computers using serial cables.

The topology of a typical FireWire implementation can be complex, but it is typically a hierarchical or tree topology consisting of various IEEE 1394 components. More complex topologies, including several computers sharing portions of the peripheral network, are also possible. The illustration shows how you can use FireWire. The four types of components you can use in a FireWire implementation are

  • Devices: Typically have 3 ports but can have up to 27 ports and can be daisy-chained up to 16 devices. 
  • Splitters: Provide extra IEEE 1394 ports if needed to accommodate the number and arrangement of devices used.
  • Repeaters: Overcome distance limitations in IEEE 1394 cables.
  • Bridges: Isolate traffic within a specific portion of an IEEE 1394 bus. 
FireWire devices

FireWire connections have a maximum distance of 4.5 meters, but up to 16 components can be daisy-chained to a maximum distance of 72 meters without using repeaters.


Windows operating systems resets the FireWire bus and assigns new physical addresses to IEEE 1394 devices when:

  • Devices are added or removed from the bus
  • The system is rebooted

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