A while ago Cisco added dynamic FCoE support to Nexus 5000 switches. It sounded interesting and I wanted to talk about it in my Data Center Fabrics update session, but I couldn’t find any documentation at that time.
In the meantime, the Configuring Dynamic FCoE Using FabricPath configuration guide appeared on Cisco’s web site and J Metz wrote a lengthly blog post explaining how it all works, triggering a severe attack of déjà vu.
I called Cisco’s traditional approach to multi-hop FCoE dense-mode FCoE – every switch in the network is a Fibre Channel Forwarder (FCF – Fibre Channel equivalent of a router) with a unique Domain ID participating in FSPF.
Tony Bourke wrote an even more structured blog post on multihop FCoE topologies. Definitely worth reading.
Dynamic FCoE is Cisco’s implementation of sparse-mode FCoE (note that my blog post describing it is four years old) – the leaf switches (Nexus 5000s) are FCFs, core switches provide layer-2 FabricPath-based transport between the leaf switches. There really is nothing new under the sun ;)
Does dynamic FCoE make sense? It depends. If you’re willing to trust the layer-2 transport fabric and treat storage as yet another application on top of Ethernet+IP, dynamic FCoE makes perfect sense, but keep in mind that you’ll have as much visibility into underlying transport fabric as with iSCSI or NFS… or overlay virtual networks.
FCoE is just one of the many topics described in the storage section of my Data Center 3.0 for Networking Engineers webinar.