Quoting Jeremy Visser (jeremy@visser.name):
This is false, unless proven otherwise.
You know, I really had no idea that several people were going to glom like shark-hungry ramoras onto a half-remembered guess regarding an entirely tangential subject that I threw casually into a thread where I was _actually_ attempting to make the point that various open-source client packages are often able to connect to even badly designed and implemented crypto gateways mandated by inept and hapless managers. The first name that leapt to mind happened to be OpenVPN, rather than OpenSWAN, strongSWAN, n2n, (formerly) FreeS/WAN, just the Linux IPsec stack by itself, or what-all. But the point was that what's available in that department often suffices. (The point was not which one of those I happened to mention.) I personally have been lucky enough to, in general, just use standard Unix tools and ssh tunnels, as I also mentioned. Sucks to be you guys and have to do L2TP over IPSEC and similar demented things, so you _do_ have my sympathies.
OpenVPN is a non-standard VPN protocol not supported by Cisco.
Since you're being unbelievably picky: No, OpenVPN is not a protocol at all, regardless of whether standard or not.