Sun Microsystems 220R service manual Automatic Negotiation

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:

Transmitter

Receiver

4Clock generation module 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:

PCS control

MII registers

IEEE 1149.1 controller (JTAG compliance)

IEEE 802.3u auto negotiation

The next sections provide brief descriptions of the following:

Automatic negotiation

External transceivers

External cables

Connectors

4MII power

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 ♦ January 2000, Revision A