BigFoot Networks Killer NIC: Killer Marketing or Killer Product?

Killer NIC Technology

Hopefully you are still with us after the previous segment as writing it was better than taking a dose of Lunesta. In all seriousness, the technology of offloading network transactions to a dedicated processor has proven to be very beneficial in the corporate server environment. The typical TNIC is designed to handle data payloads that are larger than 8KB and in certain instances will have reduced performance (lower throughput and higher latencies) with smaller and more frequent data payloads in the 1KB to 4KB range. This range is what most messaging traffic, web services, and real-time data applications such as games utilize at this time. TNICs are generally optimized for TCP (transmission control protocol) packets where the vast majority of games today utilize UDP (user datagram protocol) packets for data transmission.

The differences between the two protocols are numerous but we will hit the highlights. TCP has a standard header length of twenty bytes versus eight for UDP. The normal TCP header will contain metric information such as sequence and acknowledgement numbers along with a requirement for a checksum number. UDP packets do not include metrics and the checksum information is optional. In other words, UDP does not provide the reliability, security, or ordering (queue) guarantees that TCP can deliver. The datagrams in the UDP packet may arrive out order or not at all and your system or application may never notice. Unlike TCP, UDP provides no guarantees for delivery or proper queuing, so why use it? The answer is simple: UDP is faster and far more efficient for time sensitive applications such as gaming, and you don't need every data packet to game properly. (I.e., if you miss one packet that says player X is at coordinates (10,10,15) but you get the next packet that shows X at (12,11,15), the missing packet will not seriously impact the overall experience unless of course you missed a shot or took one.) With this simple premise in mind BigFoot Networks decided to take TOE technology and design a TNIC that focused on UDP protocols and latency reduction.

The main technology focus of BigFoot Networks is centered on their LLR technology. LLR (Lag and Latency Reduction) technology that implements a 1-packet 1-interrupt model to eliminate the entire queuing and buffering operations standard NICs do during the packet receipt and transmission process. When in game mode, the Killer NIC will also completely bypass the Windows networking stack which contributes to further latency or lag reductions depending upon the application. When BigFoot Networks discusses ping improvements in games they are not talking about reducing ping through your network or at the server. This is completely out of their control and although their marketing information is not clear about it the reduction in ping comes on the host machine. These reductions come from bypassing the Windows Network Stack while in Game mode. Depending upon the application and packet size there is generally a 1~3ms delay due to system buffering and another 3~10ms delay in the queuing and processing of data packets in the current Windows Network Stack.

What makes LLR work is the NPU (network processing unit) on the card. This processor powers both the Windows Network Stack bypass engine and the 1-packet 1-interrupt model. In short, this NPU gets the normal network transactions out of the graphics path in games. This can result in improvements in FPS (frames per second) and reduced lag. With a standard network card, before nearly every graphics frame is drawn, there is first a check to the server to see if a new data packet has arrived or if one needs to be sent. Checking the server for new data packets can use up processor clock cycles whether or not data is there. Instead of a multitude of interrupts as we discussed earlier, the Killer NIC will receive or send those data packets in a single instruction. The Killer NIC has the further ability of interrupting the game directly when new data arrives. The Killer NIC is designed around reducing latencies and not throughput.

While LLR technology is impressive to some degree we have to temper any enthusiasm with the fact that most games are designed very differently in their handling of network tasks. Some games do not check for new network data on every graphics frame so any FPS improvements will be minimal at best or completely nonexistent the majority of time. Several older games do not use UDP packets so performance could suffer as the Network Stack bypass model is not used and the card must act as standard NIC. The one thing that we have learned during testing is that many games do not report accurate latency (ping rates) so any improvements are not as measurable but at times can be felt do to smoother game play. The basic TOE and TNIC technology still applies to this card and has been proven over the past few years in the corporate server environment. Converting this technology to the desktop with the added spin of improving gaming is certainly an admirable feat but how well does it work? We will answer that question in a few pages but first let's take a look at the obligatory marketing information.