Transmit fast-path processing on TCP/IP offload network interface device

A method of generating a fast-path response to a packet received onto a network interface device, the packet being received over a TCP/IP network connection, the TCP/IP network connection being identified at least in part by a TCP source port, a TCP destination port, an IP source address, and an IP destination address, the method comprising:

• on the network interface device examining the packet and determining from the packet the TCP source port, the TCP destination port, the IP source address, and the IP destination address;
• accessing a template header stored on the network interface device, the template header having TCP fields and IP fields;
• filling in the TCP fields and IP fields of the template header using the determined TCP source port, TCP destination port, IP source address, and IP destination address, the TCP fields and IP fields being filled in without passing the template header down from any TCP protocol processing stack layer to any IP protocol processing stack layer;
• and
• transmitting the fast-path response from the network interface device, the filled in template header forming at least a part of the fast-path response.

A method for generating a third TCP packet from a network interface device, the network interface device being coupled to a network and being coupled to a host, the host executing a network protocol stack comprising a plurality of network processing protocol layers, the network interface device comprising a processor, the method comprising:

• receiving a first TCP packet onto the network interface device from the network, the first TCP packet being received via a first network connection;
• slow-path processing the first TCP packet such that the stack performs substantial TCP layer processing on the first TCP packet;
• receiving a second TCP packet onto the network interface device from the network, the second TCP packet being received via a second network connection, the second network connection being a TCP/IP connection;
• and
• fast-path processing the second TCP packet such that the stack of the host performs substantially no TCP layer processing on the second TCP packet, wherein in response to said receiving of the second TCP packet the network interface device generates the third TCP packet, the generating of the third TCP packet comprising:
• accessing a template header stored on the network interface device, the template header having TCP fields and IP fields;
• and
• using the processor to fill in the TCP fields and the IP fields in the template header to form the third TCP packet without passing the third TCP packet or the template header down to any lower protocol processing layer in any protocol stack.