What Makes SmartNICs "Smart"

Standard Network Interface Cards (NICs) are engineered to convert electrical signals from the Ethernet into data, structuring this data into packets, then sorting these packets into the appropriate queues for specific host applications. Dozens of applications can use the same physical network interface, each with its unique logical network port. Using this logical port assignment, the NIC steers traffic to the appropriate host memory addresses for these applications. Some argue that NICs do far more. They detect and sometimes correct error conditions and compute checksums to detect data corruption. They can provide a series of well-understood kernel offloads, etc., but these are valued added features designed to improve overall system performance. 

SmartNICs do all the above, but they can also do much more. For example, they can apply rules to the structured data, known as packets, as the packets enter or are preparing to leave the SmartNIC. In this way, a SmartNIC can act like a firewall allowing or denying packets to pass. These rules could be implemented in various ways and can apply other actions. Collections of packets with the same source and destination addressing and protocol are known as a “flow.”

A SmartNIC is designed to operate on flows, like a router, by utilizing a massive table of flows that match to actions assigned to them. A Generic Flow Table (GFT) is a simple method to map a specific flow to an action. By adding a rules engine and a GFT, a SmartNIC can easily emulate a networking switch, often offloading the server’s own hypervisor’s virtual network switch within the SmartNICs infrastructure. Over the next few months, on the run-up to the SmartNIC Summit, we’ll dive into what makes a SmartNIC different from a standard NIC, going into detail on things like rules, content addressable memory, and generic flow tables. 

This year from June 13-15, the SmartNIC Summit will be held for the second time in San Jose, California, USA, at the Doubletree next to the airport. If you're interested in SmartNICs, you should seriously consider attending or even presenting. The Call for Papers is currently open.