if you put something like host * ControlMaster auto ControlPath ~/.ssh/master-%r@%h:%p in your .ssh/config, any additional ssh sessions to a h

if you put something like host * ControlMaster auto ControlPath ~/.ssh/master-%r@%h:%p in your .ssh/config, any additional ssh sessions to a host reuse the original connection, so a new link doesn't have to be renegotiated.