Xilinx 1000BASE-X - Manual (Page 153)

Ethernet 1000BASE-X PCS/PMA or SGMII v9.1 www.xilinx.com 153
UG155 March 24, 2008
R
Chapter 10
Auto-Negotiation
This chapter provides general guidelines for using the Auto-Negotiation function of the
Ethernet 1000BASE-X PCS/PMA or SGMII core. Auto-Negotiation is controlled and
monitored through the PCS Management Registers and is only available when the optional
MDIO Management Interface is present. For more information, see
Chapter 9,
“Configuration and Status.”
Overview of Operation
For either standard, when considering Auto-Negotiation between two connected devices,
it must be remembered that:
•
Auto-Negotiation must be either enabled in both devices, or:
•
Auto-Negotiation must be disabled in both devices.
1000BASE-X Standard
IEEE 802.3 clause 37 describes the 1000BASE-X Auto-Negotiation function that allows a
device to advertise the modes of operation that it supports to a device at the remote end of
Figure 10-1: 1000BASE-X Auto-Negotiation Overview
Ethernet 1000BASE-X
PCS/PMA or SGMII
Core
Virtex-II Pro Device
Ethernet
Media
Access
Controller
PowerPC
MDIO
CoreConnect
an_interrupt
Auto-Neg Adv
(Reg 4)
Link Partner Ability
Base (Reg5)
Link Partner
Auto-Neg Adv
(Reg 4)
Link Partner Ability
Base (Reg5)
Optical
Fibre