Power Management Considerations for Gigabit Ethernet NICs (NDIS 5.1)
Note NDIS 5. x has been deprecated and is superseded by NDIS 6. x. For new NDIS driver development, see Network Drivers Starting with Windows Vista. For information about porting NDIS 5. x drivers to NDIS 6. x, see Porting NDIS 5.x Drivers to NDIS 6.0.
When a gigabit Ethernet NIC is operating at 1000 Mbps, it uses a lot of electrical power. Before such a NIC transitions to a low-power state, its link speed is typically reduced so that the NIC uses less power. The reduced link speed enables the NIC to transition to a low-power state. While changing link speeds during the transition to a low-power state, the NIC typically loses network connectivity for a short time.
Conversely, when a gigabit Ethernet NIC transitions to the fully on state from a low-power state, the NIC's link speed is increased to its fully operational rate. During this transition, the NIC might also lose connectivity for a short time.
While a miniport driver's underlying NIC is transitioning to or from a low-power state, the miniport driver must not indicate either a change in link speed or a change in connection status. For more information about indicating a change in link speed, see NDIS_STATUS_LINK_SPEED_CHANGE. For more information about indicating a change in connection status, see Indicating Connection Status.