One element of Cloud is being able to easily move workloads around, in and out. The harder this is the more difficult the adoption. If you have ever architected or even harder, implemented, a DR solution you know that re-addressing the networking for a pile of machines can be either difficult, "non-trivial" or just down right impossible. At the same time we see companies such as EMC and F5 working on doing VMotion across sites.

An outcome of this workload migration into the Cloud and long term VMotion across sites is the spreading of layer 2 networks across physical sites. Of course this can be done today but there are all sorts of limitations and difficult bits.

Cisco have been working hard on this problem and have come up with Overlay Transport Virtualization (OTV).

Some big players such as Terremark have been trailing OTV, interconnecting three of their data centres. "[...] the company likes what it has seen as an early beta tester of OTV and the Nexus 7000 switches it runs on. Interconnecting data centers takes minutes instead of several hours, says Mike Duckett, Terremark’s general manager of network services." You can read more about Terremark and OTV at this Network World article.

Also, Omar Sultan of Cisco has posted some initial information and a video [shown below] detailing more about OTV.

Its important to note that at the moment OTV is a "Nexus 7000 specific feature" and that they are looking at supporting other platforms and submitting to the standards bodies. I think this is critical for Cisco, there is a lot of Catalyst 6500's out there and not all enterprises may be willing to migrate to the higher end Nexus rage yet without having all of the service modules available.

If you are thinking Cloud for the Enterprise, then my advise is you want to keep an eye on OTV.

Rodos