Broadcom, Adaptec put TOE in Microsoft's Chimney. (Storage News Review).

Broadcom Corp has made what it says is a major bet that TCP/IP network accelerator technology will become a volume-selling low-end server technology, and alongside Adaptec Corp adopted an architecture defined by Microsoft Corp that is very likely to become a de facto standard. Broadcom, which claims to hold the largest market share for motherboard-mounted Gigabit Ethernet adaptors, said it is developing a TCP/IP offload engine, or TOE chip. Mounted either on network adaptor card on a server motherboard, TOEs spare the host from the processing load of handling TCP/IP packets, and so will hugely improve the performance of anything other than high-end computationally-intense servers.

"This is the biggest development we've undertaken in the last several years. It was a huge investment to get Gigabit Ethernet affordable, and this is just as big an investment," said Allen Light, line product manager at Broadcom.

The company, whose customers include 3Com, Hewlett-Packard and IBM, would not say when it will ship the silicon it is developing, or how much it will charge for it. The cost is likely to fall to a few tens of dollars or less within the medium term.

"A few years ago, a single Gigabit adapter cost $500, and now dual-channel adapters are free on servers costing $600 to $700," Light said. "We see TCP/IP adapters on the motherboard too," Light said.

According to some vendors, TOE-powered network accelerator cards can boost server performance by 30% or more, by eliminating an overhead that can eat up to 60% of server cycles. Light said that the effect is not restricted to niche applications, but applies to common-or-garden apps such as Exchange, or web or file serving. "We play in the volume segment," he said.

Given its entry-level focus, it is no surprise that Broadcom has adopted the Chimney TCP/IP stack architecture developed by Microsoft for eventual incorporation into the recently launched Windows Server 2003.

Unlike TOEs developed for other operating systems, TOEs that run in Chimney leave nonroutine exception-handling to the operating system, making the TOE simpler and cheaper to develop. Also, only one TCP/IP stack is present on the server, and it is shared by both the Windows OS and the TOE. On other operating systems, TOES must use their own stacks, resulting in an extra IP address. Given the low-end market Broadcom is targeting, that extra management overhead and complexity could be a significant disadvantage.

Chimney is very likely to be pointing the way for other operating systems. No other vendor has yet proposed any similar architecture, Light said. Broadcom's forthcoming chips will work easily with other operating systems--provided they are modified to adopt the Chimney layout.

Underlining the lead set by Microsoft, Adaptec last week demonstrated its forthcoming TOE-powered network accelerator card working with Chimney at Microsoft's Windows Hardware Engineering Conference (WinHEC). Adaptec has not set a price for its card, or a shipping date. Earlier this quarter it began shipping an iSCSI adapter card which packages a TOE alongside silicon designed to handle protocol conversion to and from iSCSI to SCSI, and the company is also already supplying its TOE to Cisco Systems Inc.