Fortville: 40 GbE Ethernet For The Masses
Alongside the Grantley platform, Intel is introducing a new generation of Ethernet network adapters code-named Fortville. The controller is 40 Gb-capable, and it completely changes the game with regards to Intel's networking capabilities.
Given the massive performance increases enabled by today's systems, low-latency and high-bandwidth networking is essential. Grantley is built to consolidate an even greater number of virtual machines on a single server. Technologies like VMware vSAN utilize local storage to create distributed SANs for these virtual machines. Even trends like software-defined networking can benefit from higher port counts and greater networking performance. Fortville is Intel's solution.
There are three main configurations of the Fortville adapter: 2 x 40 GbE, 1 x 40 GbE, and 2 x 10 GbE. Compare that to the previous generation of Spring Fountain-based X520 adapters capable of up to 2 x 10 GbE. You quickly see the bandwidth "potential" goes up from 20 to 80 Gb/s on the Fortville X710 family.
While a 4x bandwidth increase sounds awesome, that ceiling is currently not possible to hit. Servers generally expose a bunch of eight-lane PCIe slots. Right now, the third-gen standard gives you a little less than 8 GB/s of throughput. Furthermore, there is always some overhead involved. So, hooked up to the Cray-Gnodal GS0018 (18 x 40 GbE) switch in the lab, we are seeing between 50 and 55 Gb/s of peak bandwidth. We dno't have enough data to publish formal numbers. However, there is definitely a bottleneck in play.
Still, in most deployments, the two QSFP ports will attach to different switches for failover. And there's plenty of headroom in the card to drive essentially a full 40 Gb connection, plus a solid amount through the second port.
Another aspect of 40 GbE-based products like the XL710 is that each QSFP port can utilize QSFP-to-4x SFP+ breakout cables. This allows for each XL710 card with dual QSFP ports to connect to up to 8x SFP+ 10 GbE devices. In theory, you can place eight of these dual-port cards in a server and then use that machine with 72 10 GbE network connections. The reasons not to are pretty obvious, but it's at least technically possible.
The other side of the Fortville story, aside from the controller's huge performance and density improvements, is power consumption. Fortville uses less power than the previous-gen X520 10 GbE adapters, both at idle and under load. The X520s had an 8.6 W TDP, while the XL710 generation is rated at 7 W. In a theoretical efficiency metric, Fortville delivers more than 3.5 times the throughput/watt compared to previous generation. That is a massive leap forward. Consistent with this, Fortville is rated at 3.6 W typical power consumption using two 40 GbE links, so 7 W TDP represents a lot of headroom.
At the end of the day, Intel's Fortville-based adapters should enable more bandwidth, lower latency, and higher port density, all at reduced power consumption.