
Chapter 3
Functional Operation
115
24674
Rev. 3.00
April 2003
AMD-8111 HyperTransport I/O Hub Data Sheet
AMD Preliminary Information
The Auto-Poll’s frequency of generating MII management frames can be adjusted by setting of the
APDW bits (CTRL2, bits 2-0).
3.10.12
Network Port Manager
The network controller does not require software intervention to control and configure an external
PHY attached to the MII. The controller contains an automatic configuration system called the
Network Port Manager.
The Network Port Manager initiates auto-negotiation in the external PHY when necessary and
monitors the results. When auto-negotiation is complete, the Network Port Manager sets up the MAC
to be consistent with the negotiated configuration. The Network Port Manager auto-negotiation
sequence requires that the external PHY respond to the auto-negotiation request within 7.5 seconds.
Otherwise, system software is required to properly control and configure the external PHY attached to
the MII. After auto negotiation is complete, the Network Port Manager generates MII management
frames about once every 600 ms to monitor the status of the external PHY.
The Network Port Manager is enabled when the Enable Port Manager (EN_PMGR) bit (CMD3, bit
14) is set to 1.
Although the Network Port Manager and the Auto-poll State Machine both poll the external PHY, the
two modules have different functions. The Port Manager manages auto-negotiation, while the Auto-
poll State Machine monitors user-selected external PHY registers.
3.10.13
Auto-Negotiation Support
The external PHY and its link partner may have one or more of the following capabilities: 100BASE-
T4, 100BASE-TX Full-/Half-Duplex, 10BASE-T Full-/Half-Duplex, and MAC Control PAUSE
frame processing. During the auto-negotiation process the two PHY devices exchange information
about their capabilities and then select the best mode of operation that is common to both devices.
The modes of operation are prioritized according to the order shown in Table 31 on page 115 (with
the highest priority shown at the top of the table).
Auto-Negotiation goes further by providing a message-based communication scheme called, Next
Pages, before connecting to the Link Partner. The Network Port Manager does not support this
feature. However, the host CPU can disable the Network Port Manager and manage Next Pages by
accessing the PHY device through the PHY Access Register. The host CPU can disable the Network
Port Manager by clearing the Enable Port Manager (EN_PMGR) bit (CMD3, bit 14) to 0.
Table 31.
Auto-Negotiation Capabilities
Network Speed
200 Mbit/s
100 Mbit/s
100 Mbit/s
20 Mbit/s
10 Mbit/s
Physical Network Type
100BASE-X, Full Duplex
100BASE-T4, Half Duplex
100BASE-X, Half Duplex
10BASE-T, Full Duplex
10BASE-T, Half Duplex