Full TCP Offload
NDIS 6.0 introduced an architecture for full TCP offload. This architecture is called a "chimney offload" architecture because it provides a direct connection, called a "chimney," between applications and an offload-capable NIC. The chimney enables the NIC to perform TCP processing for offloaded connections, including maintaining the protocol state.
The chimney offload architecture reduces host network processing for network-intensive applications. This allows networked applications to scale more efficiently while also reducing end-to-end latency. Fewer servers are needed to host an application, and servers are able to use the full Ethernet bandwidth.
The TCP chimney offloads all TCP processing for one or more TCP connections. The primary performance gains are obtained from offloading segmentation and reassembly (SAR), offloading processing that ensures reliable connections (for example, ACK processing and TCP retransmission timers), and reducing interrupt loading.
For information on TCP chimney offload in NDIS 6.0 and later, see NDIS TCP Chimney Offload.