From Ivan Pepelnjak’s blog, comes a nice, yet daunting thought: the Holy Grail of modern networking, massively-scalable multi service Layer 2 domains, has the ultimate goal of allowing MAC-to-MAC visibility between servers, mainly for virtualization purposes.
… everyone is running to join the gold rush, from Cisco’s FabricPath and Brocade’s VCS to HP’s IRF and Juniper’s upcoming QFabric. As always, the standardization bodies are following the industry with a large buffet of standards to choose from: TRILL, 802.1ag (SPB), 802.1Qbg (EVB) and 802.1bh (Port extenders).
The only viable argument the whole industry has for the push toward large(r) layer-2 domains is VM mobility – if you want to migrate a live virtual machine across the data center and retain its sessions, it has to stay in the same VLAN…
Ivan’s argument is surprisingly simple: it would not take much for a virtualization vendor to wake up, smell the coffee, and enable an IP-to-IP VM mobility mechanism. His conclusion is indeed clear:
All of a sudden, all we need in the Data Center is layer-3 connectivity designed and implemented using the same mechanisms we’ve been using for the last 30 years to build the (somewhat scalable) Internet. The only reason for the layer-2 gold rush is gone.
I believe that VM mobility is not the only reason behind these efforts though. IP-based mobility would not by itself solve the problem of providing a full-fledged network interface to the VM. It would not solve inter-VM policy making without further enhancements. It would not solve the management overload associated to network device sprawl.
But still, it would mean a paradigm shift for innovation in the Data Center space.