Windows® Internals, Sixth Edition, Part 1

TCP/IP offloading, including task and chimney offloading. Task offloading allows a network interface card to implement some or all of the TCP/IP protocol stack, providing a substantial increase in network performance. NDIS includes support for IPsec Task Offload Version 2, which includes support for additional cryptography suites used in IPsec, such as AES, as well as IPv6 support. Chimney offloading provides a direct connection (the so-called chimney) between network applications and the network card hardware, enabling greater offloading and connection state management to be implemented by the network card. These offloading operations can improve system performance by relieving the CPU from the tasks.

Receive-side scaling enables systems with multiple processors to perform packet receive operations based on the most efficient use of available target processors. NDIS supports the receive-side scaling (RSS) interface at the hardware level and targets interrupts and DPCs to the appropriate processors.

Wake-on-LAN allows a wake-on-LAN-capable network adapter to bring the system out of a suspended power state. Events that can trigger the network adapter to signal the system include media connections (such as plugging a network cable into the adapter), the receipt of protocol-specific patterns registered by a protocol (the TCP/IP transport asks to be woken for Address Resolution Protocol [ARP] requests), and, for Ethernet adapters, the receipt of a magic packet (a network packet that contains 16 contiguous copies of the adapter’s Ethernet address).

Header-data split allows compatible network cards to improve network performance by splitting the data and header part of an Ethernet frame into different buffers and subsequently combining the buffers into smaller regions of memory than if the buffers were combined. This allows more efficient memory usage as well as better caching because multiple headers can fit in a single page.

Connection-oriented NDIS (CoNDIS) allows NDIS drivers to manage connection-oriented media (typically, a WAN), such as ISDN or PPP devices. (CoNDIS is described in more detail shortly.)

The interfaces that the NDIS library provides for NDIS drivers to interface with network adapter hardware are available via functions that translate directly to corresponding functions in the HAL.

EXPERIMENT: Listing the Loaded NDIS Miniports