5-6
Configuration Options
Fast Link Pulse (FLP) bursts provide the signalling used to communicate
AutoNegotiation abilities between two devices at each end of a link
segment. For further detail regarding AutoNegotiation, refer to Clause 28
of the IEEE 802.3u specification. The L80600 supports six different
Ethernet protocols: 10BASE-T Full-Duplex, 10BASE-T Half-Duplex,
100BASE-TX Full-Duplex, 100BASE-TX Half-Duplex, 1000BASE-T
Full-Duplex and 1000BASE-T Half-Duplex. The inclusion of
AutoNegotiation ensures that the highest performance protocol is
selected based on the advertised ability of the Link Partner.
AutoNegotiation Priority Resolution for the L80600:
1000BASE-T Full-Duplex (Highest Priority)
1000BASE-T Half-Duplex
100BASE-TX Full-Duplex
100BASE-TX Half-Duplex
10BASE-T Full-Duplex
10BASE-T Half-Duplex (Lowest Priority)
5.3.2 AutoNegotiation Master/Slave Resolution
The second goal of AutoNegotiation in 1000BASE-T devices is to resolve
Master/Slave configuration. If both devices have disabled manual
Master/Slave configuration, Master priority is given to the devices that
support multiport nodes (switches and repeaters take higher
priority over DTEs or single-node systems.). SPEED[0]/PORT_TYPE
is a strap option for advertising the Multinode functionality (see
Table 5.4
). If both PHYs advertise the same options, the Master/Slave
resolution is resolved by a random number generation. See
IEEE 802.3ab Clause 40.5.1.2 and
Table 5.3
for more details.
5.3.3 AutoNegotiation Pause and Asymmetrical Pause Resolution
AutoNegotiation is also used to determine the Flow Control capabilities
of the two link partners. Flow control was originally introduced as a
mechanism to force a busy station’s Link Partner to stop sending data in
the Full-Duplex mode of operation. Unlike the Half-Duplex mode of
operation where a link partner could be forced to back off by simply
causing collisions, the Full-Duplex operation needs a formal mechanism
to slow down a link partner in the event of the receiving station’s buffers