[OpenSIPS-Users] NOTIFY nat_keepalive - Bad Event

[Dan Pascu]

On Monday 02 March 2009, Bogdan-Andrei Iancu wrote:
> >> Anyhow, as best practice , the OPTIONS method is more appropriate
> >> for nat pinging.
> >
> > I have to disagree. OPTIONS generate 2-3 times more traffic because
> > of the bigger replies. OTOH, it doesn't really matter if we get a 200
> > OK or a negative reply to such a keep-alive request, does it? All it
> > matters is that the device behind NAT sends something (anything) to
> > keep the NAT open from inside. NOTIFY gets the job done with less
> > traffic, which makes it better.
>
> Indeed, the OPTIONS may generate more traffic (depends on the
> implementation - kphone sends with SDP also, other not). But when comes
> to interoperability, OPTIONS is more accepted by end devices, rather
> then NOTIFY (where the phone must implement the method and the event).

I don't think the phone needs to implement or for that matter even be 
aware of the NOTIFY method. Any device should reply with a "not 
implemented" or "method not understood" negative reply to any method it 
doesn't support. Any reply will do for the purpose of keepalive, be it 
positive or negative. In practice I have not encountered any device that 
would not reply to a keep-alive NOTIFY.

-- 
Dan