What is Lossless?
In a recent post, I read that there’s no reason to wait to implement FCoE and that an underlying lossless Ethernet network is not really required. In fact, a CEO of another vendor actually proclaimed that their switch is lossless and can be used for FCoE today.In some ways, I agree. There is no reason to wait to implement FCoE today. But shouldn’t you implement it with all the features necessary for a truly lossless Ethernet? Features like Priority Flow Control (802.1Qbb), Bandwidth Management (802.1Qaz), and Congestion Management (802.1Qau)? All of these encompass what we call Data Center Ethernet and are being standardized by IEEE and supported by the Ethernet Alliance.It’s also interesting that he measures lossless capability by testing just simple forwarding on a single switch. Any modern switch can forward line-rate at different packet sizes with zero packet loss. The real question is how does an Ethernet switch handle congestion? How then does it handle storage traffic that doesn’t tolerate drops while dealing with congestion of other protocols? This is why Data Center Ethernet is required which allows you to build a lossless NETWORK, not just a lossless switch.The Cisco Nexus 5000 delivers Data Center Ethernet and FCoE today. Be sure to look at it when comparing against other so-called lossless Ethernet switches.