100BASE-TX Fast Ethernet Standards PDF

2.1.4 100BASE-TX Fast Ethernet Standards The Fast Ethernet standard uses the same CSMA/CD protocol as 10BASE-T but with higher frequency signaling and improved encoding methods, raising the bit rate from 10 Mbps to 100 Mbps. 100BASE-TX refers to Fast Ethernet working over Cat 5 (or better) twisted p...

2.1.4 100BASE-TX Fast Ethernet Standards The Fast Ethernet standard uses the same CSMA/CD protocol as 10BASE-T but with higher frequency signaling and improved encoding methods, raising the bit rate from 10 Mbps to 100 Mbps. 100BASE-TX refers to Fast Ethernet working over Cat 5 (or better) twisted pair copper cable with a maximum supported link length of 100 meters (328 feet). 100BASE-TX can be implemented with a hub, but the standard was created at a time that switches started to replace hubs as the connection point for end systems. The contention-based access method used by a hub does not scale to large numbers of end systems within the same collision domain. Where a hub works only at the Physical layer, a switch uses information about source and destination addresses carried in layer 2frames to establish a temporary circuit between two nodes. Unlike a hub, each switch port is a separate collision domain. By eliminating the effect of contention, switches allow for full-duplex transmissions, where a node can transmit and receive simultaneously, and each node can use the full 100 Mbps bandwidth of the cable link to the switch port. To support compatibility with hosts still equipped with 10 Mbps Ethernet interfaces, Fast Ethernet introduced an autonegotiation protocol to allow a host to choose the highest supported connection parameters (10 or 100 Mbps and half- or full-duplex). 10BASE-T Ethernet specifies that a node should transmit regular electrical pulses when it is not transmitting data to confirm the viability of the link. Fast Ethernet codes a 16-bit data packet into this signal, advertising its service capabilities. This is called a Fast Link Pulse. A node that does not support autonegotiation can be detected by one that does and sent ordinary link integrity test signals, or Normal Link Pulses. Fast Ethernet would not be deployed on new networks, but you may need to maintain it in legacy installations. Copyright © The Computing Technology Industry Association, Inc. All rights reserved.