Blade server switch and NIC communicate to improve latency
Start-up Teak Technologies debuted a 10G Ethernet switch for blade servers this week. The hook is a new traffic-management and congestion-detection technology built into the hardware, which, the company says, eliminates latency and makes standard 10G connections look slow.
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“Data-center switches have behaved in isolated silos — traffic is just thrown at them from the endpoints,” says Sanjay Dua, chief marketing officer for Teak. “If the switch can handle it, it does, if not, it starts to drop packets. That’s when congestion occurs, and application availability suffers due to latency.”
Teak’s switches work with special NICs in blade servers, developed with the start-up’s congestion-management and protocol-offloading technology. Neterion, a maker of 10G Ethernet NICs, is the first partner to announce it is working with Teak. (It’s Teak-infused NICs work with Microsoft Windows and Linux servers). The Neterion/Teak NICs and the blade server switch module communicate information about upstream network congestion, using Layer 2 signaling mechanisms.
If the switch module detects congestion from other Teak-enabled server blades, or with other switches outside the chassis, it can signal the NIC to “back off” the rate at which it is pumping frames into the network. Teak switches connected to each other can also send this message to throttle down traffic rates during high congestion periods. This split-second limiting of traffic during congestion can save a machine from having to re-transmit the Ethernet frame if the data is dropped by a congested switch. The end result is faster-reacting applications, and data streams that don’t drop frames — an essential trait for Ethernet-based storage, or clustered computer systems.
“We have reactive mechanisms [in the switches and NICS] that are able to detect the likelihood of congestion, and can react by communicating to endpoint’s I/Os to back off momentarily, Dua says. “If you can establish coordination between switches and endpoints, and between switches and next-hop switches, you can create this collaborative environment, which leads to what we call a congestion-free zone in a data center.”
Some of the techniques Teak uses are outlined by the IEEE 802.3ar Congestion Management Task Force, which is working on bringing some congestion-management methods defined by the IETF at the TCP/IP layer (Layers 3 and 4) down to Layer 2.
“We’re a little bit ahead of that standards body, in that we’re actually commercializing the technology and showing that it can work,” Dua says. “We’re also making some advancements of where some of the ideas are currently at in that standards body.”
While Teak unveiled its blade server switch and NIC technology this week, it plans to launch a stand-alone Ethernet switch with its congestion-management technology later this year. This would help create a full congestion-managed data-center Ethernet network, which could carry application server traffic, as well as IP storage, via protocols such as iSCSI and Fibre Channel over Ethernet.
Teak says it’s in-chassis blade switches and its forthcoming stand-alone switches interoperate with standard 10G Ethernet switches, such as 3Com, Cisco, Enterasys, Extreme, Force10, Foundry and Nortel gear. Using the traffic-congestion technology requires a Teak technology on both sides of the Ethernet pipe.
These “top-of-rack” switches — so-called because they would sit at the end of a rack of blade chassis — would provide all interconnections among blade server racks in the data center, Dua says.
Teak’s approach is somewhat similar to that of start-up Woven Systems, which debuted its Ethernet Fabric Switch 1000 in April. Woven’s switch provides multipath meshed switching at Layer 2, with a proprietary congestion detection mechanism for routing around oversubscribed points or bottlenecks in a data center.
Teak also competes with blade server-focused switch vendors, such as Cisco, with its Catalyst Blade Switch 3040, and Blade Network Technologies, the former blade server switch division of Nortel.
