Freescale Semiconductor TWR-MCF52259-Ethenet manual Autonegotiation

*Autonegotiation

Auto-Negotiation is the exchange of information about each stations abilities over a link segment allows the stations to achieve the best possible mode of operation.

The highest performance mode of operation that Auto-Negotiation can achieve is based on a priority table.

The Auto-Negotiation protocol contains a set of priorities which result in the devices selecting their highest common set of abilities.

If the devices at both ends of the link can support full duplex operation, and if they also both support Auto-Negotiation of this capability, then they will automatically configure for full duplex.

The priorities are listed in the table below...

Auto-Negotiation priority Resolution Table

A	100		Base-TX Full Duplex
B	100		Base-T4
C	100		Base-TX
D	10	Base-T Full Duplex
E	10	Base-T Half Duplex

Full duplex is given a higher priority than half duplex, since it can send more data.

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