Scalability of ocserv

[Nikos Mavrogiannopoulos]

On Fri, Aug 28, 2015 at 2:40 PM, Valentin Sawadski <valentin at tado.com> wrote:
> Hello everyone,
> I was wondering if there is any reference as to how big OpenConnect's
> ocserv can scale in the terms of simultaneous connected clients?
> Assuming the clients generate little traffic (less than 1 Megabyte per
> Minute), how many connections could a dedicated server handle?

I haven't had any experience with ocserv and such a high number of
users, but after the clients connect no matter what they do it doesn't
affect the overall performance (as long as you have enough CPUs to
cope with the traffic).  The bottleneck would be the login process as
not parallelism exists during authentication, and as you mention the
number of clients would be limited by the number of tun devices that
can be handled by the kernel.

However, I'd also be interested in any data/stats when a high number
of users is involved. I'm experimenting with a branch where ocserv
uses libev for more efficient handling of resources when the number of
users increases. That should affect mostly the client connection time,
however I have not seen much of a difference in performance on the
level of 1000-3000 users.

regards,
Nikos