Converge your network with explicit congestion notification
Every now and again, we like to highlight a piece of technology or solution featured in Cumulus Linux that we find especially useful. Priority Flow Control (PFC) and Explicit Congestion Notification (ECN) are exactly such things. In short, these technologies allow you to converge networks and save money. By supporting lossless or near lossless Ethernet, you can now run applications such as RDMA over Converged Ethernet (RoCE) or RoCEv2 over your current data center infrastructure. In this post, we’ll concentrate on the end-to-end solution for RoCEv2 – ECN and how it can help you optimize your network. We will cover PFC in a future post.
What is explicit congestion notification?
ECN is a mechanism supported by Cumulus Linux that helps provide end-to-end lossless communication between two endpoints over an IP routed network. Normally, protocols like TCP use dropped packets to indicate congestion, which then tells the sender to “slow down’. Explicit congestion notification uses this same concept, but instead of dropping packets after the queues are completely full, it notifies the receiving host that there was some congestion before the queues are completely full, thereby avoiding dropping traffic. It uses the IP layer (ECN bits in the IP TOS header) Continue reading
