Intel GD82559ER - Manual (Page 11)

Datasheet 5
Networking Silicon — GD82559ER
2.3 10/100 Mbps Serial CSMA/CD Unit Overview
The CSMA/CD unit of the 82559ER allows it to be connected to either a 10 or 100 Mbps Ethernet
network. The CSMA/CD unit performs all of the functions of the 802.3 protocol such as frame
formatting, frame stripping, collision handling, deferral to link traffic, etc. The CSMA/CD unit can
also be placed in a full-duplex mode, which allows simultaneous transmission and reception of
frames.
2.4 10/100 Mbps Physical Layer Unit
The Physical Layer (PHY) unit of the 82559ER allows connection to either a 10 or 100 Mbps
Ethernet network. The PHY unit supports Auto-Negotiation for 100BASE-TX Full Duplex,
100BASE-TX Half Duplex, 10BASE-T Full Duplex, and 10BASE-T Half Duplex. It also supports
three LED pins to indicate link status, network activity, and speed.The 82559ER does not support
external PHY devices and does not expose its internal MII bus.