Specifications

CHAPTER
1-1
Cisco PA-FE-TX and Cisco PA-FE-FX Fast Ethernet 100BASE-T Port Adapter Installation and Configuration
OL-2899-02
1
Overview
This chapter describes the Cisco PA-FE-TX and Cisco PA-FE-FX port adapters and contains the
following sections:
• Fast Ethernet Overview, page 1-1
• Port Adapter Overview, page 1-2
• IEEE 802.3u 100BASE-T Specifications, page 1-3
• LEDs, page 1-4
• Cables, Connectors, and Pinouts, page 1-5
• Port Adapter Slot Locations on the Supported Platforms, page 1-8
• Identifying Interface Addresses, page 1-21
Fast Ethernet Overview
The term Ethernet is commonly used for all carrier sense multiple access/collision detection
(CSMA/CD) LANs that generally conform to Ethernet specifications, including Fast Ethernet under
IEEE 802.3u.
Note 100BASE-TX is intended for Environment A, and 100BASE-FX is intended for
Environment B. Both are described in the IEEE 802.3u standard.
IEEE 802.3u is well suited to applications where a local communication medium must carry sporadic,
occasionally heavy traffic at peak data rates. Stations on a CSMA/CD LAN can access the network at
any time. Before sending data, the station listens to the network to see if it is already in use. If it is in
use, the station waits until the network is not in use, then transmits. This process is known as half-duplex
operation. A collision occurs when two stations listen for network traffic, hear none, and transmit almost
simultaneously. When simultaneous transmission occurs, 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 802.3u 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 802.3u specifies the following different physical layers for 100BASE-T: