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News and New Products
New again: Speed trends revive protocol offloading
By Maury Wright, Editor-In-Chief -- EDN, 5/12/2004
In the tech industry it's regularly déjà vu all over again. And right now that phrase applies to network protocols. News from this week's N+I and last week's WinHEC highlights growing interest in offloading network tasks into dedicated hardware—an idea that isn't exactly new.
In fact, the first article that I ever wrote about TCP/IP, back in the '80s, described the need for a dedicated processor to handle the overhead of the protocol. As time passed, however, CPUs got so fast that a system's main processor could handle TCP/IP in its spare time. Now, however, things have come full circle. With technologies such as video-on-demand driving a transition to 1- and 10-Gbps data rates, host CPUs again need some help.
Two factors are driving the trend toward offloading protocol processing: richer media streams and the fact that previously separate forms of traffic—storage, management, and data—are being combined on one fast network. Indeed, technologies such as Fibre Channels for SANs (storage area networks) will likely disappear with technologies such as Ethernet-connected storage and the iSCSI (Internet small computer systems interface) protocol taking over. All in all, we have a number of protocols, including TCP/IP, iSCSI, and RDMA (remote direct memory access) that bog down host CPUs as data rates go up.
Last week, Seattle-based Alacritech made news with the latest rev of its TOE (TCP Offload Engine): the STA2000 Internet Protocol Processor. The company touts the dual-port 1-Gbps IC as a perfect match for the new modular TCP/IP stack from Microsoft, which is called Chimney and is due in server versions of Windows.
This week, Broadcom announced its C-NIC (Converged Network Interface Card) family, as well as the first product in that family. The BCM5706 combines protocol processing with a Gigabit-Ethernet controller. The label "converged" refers to the melding of storage, management, and data traffic on one network.
In the long term, there's no question that protocol offload will happen. But these early products from Broadcom and Alacritech may struggle to reach high volume. At $120 in production volumes, the Alacritech offering is simply too expensive relative to the value it offers. Protocol offload is becoming an issue, but at the predominant 1-Gbps rates, designers can still address the issue with general-purpose CPUs. Broadcom has a much better chance of near-term success with its BCM5706, priced at $35.
The battle, however, will really be joined at 10-Gbps speeds—both as data centers adopt 10-Gbps links and as aggregate speeds inside boxes hit 10-Gbps based on traffic from multiple Gigabit ports. And ironically, while Alacritech and Broadcom are getting headlines today, San Diego startup Astute Networks is far ahead of them in handling 10-Gbps traffic.
Astute has taken a different approach to protocol offloading. The company started with a design based on 10 32-bit Tensilica RISC cores rather than bolting protocol processing onto an Ethernet chip. Leveraging the processors, a hardwired flow controller, an event dispatcher, and fast memory, the Astute team tuned its Pericles IC to handle protocol offload at 10-Gbps speeds.
The device can handle more than 200,000 TCP/IP connections per second and perform full TCP/IP offload at 11-Gbps. What's more, the IC consumes only 10W working at full 11-Gbps rates. The current Pericles sports dual SPI-4 (System Packet Interface level 4) ports, but the company promises to integrate Ethernet functionality in the next generation of products.
