NDIS Drivers
When a protocol driver wants to read or write messages formatted
in its protocol's format from or to the network, the driver must
do so using a network adapter. Because expecting protocol drivers
to understand the nuances of every network adapter on the market
(proprietary network adapters number in the thousands)
isn't feasible, network adapter vendors provide device drivers
that can take network messages and transmit them via the vendors'
proprietary hardware. In 1989, Microsoft and 3Com jointly
developed the Network Driver Interface Specification (NDIS),
which lets protocol drivers communicate with network adapter
drivers in a device-independent manner. Network adapter drivers
that conform to NDIS are called NDIS drivers or NDIS miniport
drivers. The version of NDIS that ships with Windows 2000 is
NDIS 5.
On Windows 2000, the NDIS library
(\Winnt\System32\Drivers\Ndis.sys) implements the NDIS boundary
that exists between TDI transports (typically) and NDIS drivers.
As is Tdi.sys, the NDIS library is a helper library that NDIS
driver clients use to format commands they send to NDIS drivers.
NDIS drivers interface with the library to receive requests and
send back responses. Figure 13-18 shows the relationship between
various NDIS-related components.
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