Cisco Systems manual Ieee 802.3 10BASE-FL Specifications, Ieee 802.3 10BASE-FL Specifications

IEEE 802.3 10BASE-FL Specifications

changes. Together, Ethernet and IEEE 802.3 are the most widely used LAN protocols. They are well suited to applications where a local communication medium must carry sporadic, occasionally heavy traffic at high peak data rates.

The term 10BASE-FLis an abbreviation for 10 Mbps transmission, Baseband medium, F for fiber, and L for link, as defined in the 10BASE-FL specification. The Ethernet specifications call the 5EFL device a transceiver, and it is connected to the station with a transceiver cable. The 5EFL port adapter is not an end station. The IEEE 802.3 specifications refer to the same type of device as a media attachment unit (MAU). Stations on a CSMA/CD LAN can access the network at any time. Before sending data, the station listens to the network to see of it is already in use. If it is, the station waits until the network is not in use, then transmits. A collision occurs when two stations listen for network traffic, hear none, and transmit simultaneously. When this happens, both transmissions are damaged, and the stations must retransmit. The stations detect the collision and use backoff algorithms to determine when they should retransmit.

Both Ethernet and IEEE 802.3 are broadcast networks, which means that all stations see all transmissions. Each station must examine received frames to determine whether it is the intended destination and, if it is, pass the frame to a higher protocol layer for processing. IEEE 802.3 specifies several different physical layers, and Ethernet defines only one. Each IEEE 802.3 physical layer protocol has a name that summarizes its characteristics in the format speed/signaling method/segment length where speed is the LAN speed in Mbps, signaling method is the signaling method used (either Baseband or Broadband), and segment length is the maximum length between stations in hundreds of meters. The maximum distances for Ethernet network segments and connections depend on the type of transmission cable used; for example, fiber-optic cable (10BASE-FL).

IEEE 802.3 10BASE-FL Specifications

Table 2 summarizes the characteristics of IEEE 802.3 Ethernet and Ethernet 10BASE-FL.

Table 2	IEEE 802.3 Ethernet and Ethernet 10BASE-FL Physical Characteristics
	IEEE 802.3	10BASE-FL
Parameter	Ethernet	Ethernet
Data Rate (Mbps)	10	10
Signaling method	Baseband	Baseband
Media	50-ohm coax (thick)	Multimode optical fiber
Topology	Bus	Star

Table 3 lists the distance limitations for 10-Mbps transmission over multimode optical-fiber cables.

Table 3	Cable Distance Limitations for 10-Mbps 10BASE-FL Transmission
Parameter		ST Connections
Cable specification		Multimode fiber-optic cable 1
Maximum segment lengths		400 m (1,312 ft) for any repeater-to-DTE fiber segment
		500 m (1,640 ft) with four repeaters and five segments
		1000 m (3,280 ft) for any inter-repeater fiber segment
		2km (6,561 ft) without a repeater

1 Cisco Systems does not supply fiber-optic cables; these cables are available commercially.

PA-5EFL Ethernet 10BASE-FL Port Adapter Installation and Configuration 7