Spirent SmartBits System, Справочное руководство

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Appendix B: Auto Negotiation
10/100/1000Mbps Copper Ethernet Auto Negotiation
SmartBits System Reference 199
The following steps are taken to achieve synchronization that implements the
synchronization state diagram in IEEE 802.3z document Figure 36-9; after
synchronization occurs, the auto negotiation process is initiated.
Loss of fiber
1 Acquire fiber detect, by using a signal from the transceiver (OCP) that indicates fiber
connected.
Loss of sync
2 Send comma pattern continuously with configuration data of all zeroes.
3 Wait for response from the DUT.
4 If no response is received from the DUT, continue the above steps.
5 Once both sides receive comma pattern, then the synchronization state diagram is fol-
lowed to complete the synchronization process.
6 If any time during the synchronization process an error condition is detected, the
entire synchronization process is restarted from Step 1.
7 Declare synchronization acquired if no errors are detected.
Auto negotiation
8 Auto negotiation process can start.
9 Once synchronization has been achieved, the SmartBits firmware/hardware starts
monitoring the PCS state transitions, following it through the auto negotiation pro-
cess.
10/100/1000Mbps Copper Ethernet Auto Negotiation
The capabilities of an interface depend upon the capabilities of the PHY transceiver that is
used with the interface. For auto negotiation on 10/100Mbps links, the PHY transceiver
uses a set of registers to store information about its capabilities. These registers are called
MII registers , referring to the 100BASE-T specification of a Media Independent Interface,
or MII. There are 32 PHY registers altogether; however, only a few of these are involved
in auto negotiation. Each MII register stores a 16-bit value. Individual bit definitions are
used to indicate the presence or absence of specific operating capabilities, as well as for
control information and status information.
Note: See “Summary of MII Registers and Bit Definitions” on page 204 for lists of all
MII registers, their functions, and bit definitions.
For these Ethernet transmission technologies, the following PHY registers are used.
•
Control Register (Register 0) . This sets control and management functions—for
example, to enable or disable the auto negotiation protocol, to restart the protocol
(normally performed when the link initializes), or to force speed and duplex settings
to desired values for the interface.
•
Status Register (Register 1) . This read-only register defines the capabilities of the
PHY as currently set, as well as some latched conditions.