With network protocols placing an ever-increasing load on CPUs, many vendors have developed "smart" NICs that implement certain network protocols in hardware. The problem with these is that the NIC implementation often differs from the OS implementation. In particular, the TCP/IP stack included in the NIC is often different from the OS's, meaning that applications taking advantage of an OS's TCP/IP stack need to be rewritten (see "iSCSI Makes SANs More Affordable").
Broadcom thinks it has a solution in TCP/IP Chimney, a chip that implements the complete Windows TCP/IP stack, licensed from Microsoft. This means that Windows applications can off-load their TCP/IP processing to hardware without any rewriting. Microsoft is making TCP/IP Chimney available to many chip vendors, though Broadcom is the first to implement it in its NetXtreme II Gigabit Ethernet Controller.
In addition to the Microsoft TCP/IP stack, the NetXtreme II also contains hardware support for iSCSI and Remote Direct Memory Access (RDMA) over IP, standards that handle networked access to storage and memory, respectively. Although most Windows servers don't need use these yet, Broadcom believes that NICs containing them will be a useful investment, as they cost little more than a regular Gigabit Ethernet NIC. When embedded on a motherboard, the chip will add about $70 to the price of a server, while a PCI NIC will cost about $200.
The first vendor to ship servers containing the NetXtreme II is HP, which estimates availability in early 2005. Although applications won't need to be rewritten, Windows does need drivers for TCP/IP Chimney, which Microsoft hasn't made available yet. HP estimates that these will be available by the time its servers ship. Other OS vendors can also take advantage of NetXtreme II's TCP/IP, iSCSI, and RDMA offload capability, though their OSs and applications will need more extensive changes.
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