[PATCH V2 11/11] library: Add setup_tun() callback

[Nikos Mavrogiannopoulos]

On Tue, Mar 8, 2016 at 11:22 AM, David Woodhouse <dwmw2 at infradead.org> wrote:
> Then the cstp_pkt could be sized for the 'negotiated MTU', as would
> deflate_pkt_size. And the *actual* MTU at any moment would be stored
> separately in a more ephemeral variable.
> Out of interest, how does this work on the server side anyway? We can
> reduce the size of the packets that *we* send, but how do we tell the
> *server* to send smaller packets? Without breaking the CSTP connection
> and reconnecting, at least?

I don't think there is a way and MTU can be different for each
direction (theoretically at least). In ocserv the server sets the
don't fragment flag and relies on ICMP to adjust the MTU size.