Sun Microsystems 220R - Manual (Page 266)

communicate between the physical signaling and the medium access control layers
for both 100BASE-TX and 10BASE-T operations. The PHY IC interfaces to the
100-Mbps physical-medium-dependent transceiver Twister IC.
The 100BASE-TX portion of the PHY IC consists of the following functional blocks:
4 Transmitter
4 Receiver
4 Clock generation module
4 Clock recovery module
The 10BASE-T section of the PHY IC consists of the 10-Mbps transceiver module
with filters.
The 100BASE-TX transceiver is included in a separate Twister IC and features
adaptive equalization, baseline wander correction, and transition time control on the
output signals.
The 100BASE-TX and 10BASE-T sections share the following functional
characteristics:
4 PCS control
4 MII registers
4 IEEE 1149.1 controller (JTAG compliance)
4 IEEE 802.3u auto negotiation
The next sections provide brief descriptions of the following:
4 Automatic negotiation
4 External transceivers
4 External cables
4 Connectors
4 MII power
4 MII port timing
C.1.10.1 Automatic Negotiation
Automatic negotiation controls the cable when a connection is established to a
network device. It detects the various modes that exist in the linked partner and
advertises its own abilities to automatically configure the highest performance mode
of inter-operation, namely, 10BASE-T, 100BASE-TX, or 100BASE-T4 in half- and
full-duplex modes.
The Ethernet port supports automatic negotiation. At power up, an on-board
transceiver advertises 100BASE-TX in half-duplex mode, which is configured by the
automatic negotiation to the highest common denominator based on the linked
partner.
266 Sun Enterprise 220R Server Service Manual
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January 2000, Revision A