For IT administrators looking to consolidate their Ethernet and Fibre Channel networks, building a converged network is a smart decision. In this Storage Decisions 2012 presentation, Demartek president Dennis Martin discusses how, when and where to build a converged network architecture using data center bridging and converged network adapters.
Let's talk about converged networks. The idea here is that you have Ethernet everywhere, and Fibre Channel [FC] in a lot of places. There are ways to run these different protocols over one carrier, but, in this case, we're talking about Ethernet as the low-level carrier. You can also do it in a rack, and in the longer term [observers] expect users will be able to do it end-to-end if needed.
You need data center bridging [DCB] for this to work. DCB is this collection of extensions to Ethernet to make it lossless, able to do flow control and [other] things Fibre Channel needs, because Ethernet likes to draw packets and you have to fix that. The Ethernet guys [at IEEE] are selling switches with DCB support in them. The first major application to use this is Fibre Channel over Ethernet [FCoE]. It’s the same Fibre Channel protocol, but it uses Ethernet as the carrier. Then you need what's known as a converged network adapter [CNA]. These adapters can run Ethernet, Fibre Channel or FCoE at the same time on the same wire. It's [useful] if you're trying to consolidate your network and want to consolidate your switches.
There's a feature called enhanced transmission selection, which allows you to regulate how much traffic goes to FCoE versus the rest of the Ethernet. FCoE runs the Fibre Channel protocol; it just runs it on a different carrier, which is Ethernet. The behavior is the same -- you have to log into the fabric, and it has to interoperate with native FC fabrics. What we've been able to show is that here's a server talking to a top-of-rack FCoE switch and we can take an optional Fibre Channel port out of that and go right into the rest of our FC SAN. Or we can [connect] the FCoE to something if the storage target, for example, supports FCoE. It looks like Fibre Channel, it's just running at 10 GbE rather than 8 Gbps.
You can get [converged networks] in blade switches and top-of-rack switches, and some of them have these optional native ports right on them. Some switches now talk about these universal ports. They can do Fibre Channel, native or Ethernet, which means that you can run FCoE, iSCSI or whatever you want, all on the same ports.
The adapters have various offload capabilities, just like in Fibre Channel where it's pretty much all offloaded. The [people] who make the Fibre Channel host bus adapters also make CNAs, and it's all offloaded. Some take 10 GbE network interface cards [NICs] and do some offloading, but the rest is done with software. These are all server-class NICs. Don't attempt this with desktop NICs, because you need a good server NIC to do this.