Data Sheet

Ethernet Controller I210 —Interconnects
114
• Forced operation
Auto-negotiation is the only method allowed by the 802.3ab standard for establishing a 1000BASE-T
link, although forced operation could be used for test purposes. For 10/100 links, any of the three
methods can be used. The following sections discuss each in greater detail.
Figure 3-16 provides an overview of link establishment. First the PHY checks if auto-negotiation is
enabled. By default, the PHY supports auto-negotiation, see PHY Register 0, bit 12. If not, the PHY
forces operation as directed. If auto-negotiation is enabled, the PHY begins transmitting Fast Link
Pulses (FLPs) and receiving FLPs from its link partner. If FLPs are received by the PHY, auto-negotiation
proceeds. It also can receive 100BASE-TX MLT3 and 10BASE-T Normal Link Pulses (NLPs). If either
MLT3 or NLPs are received, it aborts FLP transmission and immediately brings up the corresponding
half-duplex link.
3.7.8.1.1 False Link
Figure 3-16. Overview of Link Establishment
Speed?
0.13
A
/N Enabled
?
Start
Auto-Negotiate/Parallel Detection
Send NLP
Send FLP
Power-Up, Reset,
Link Failure
Forced Operation
N
Y
0
1
10M
Detect 10 Mbps
?
N
Y
Link
Down
Link
Up
Send IDLES
100M
Detect IDLES
?
N
Y
Take
Down
Link
Bring
Link
Up
Bit 0.8 sets Du
p
lex
Detect
FLP
100M
Half-Duplex
Link
N
Y
Parallel
Detect
Detect
NLP
Auto
Negotiate
Detect
IDLES
Y
10M
Half-Duplex
Link
Y
N
Bit 0.8 sets Du
p
lex
N