On 07/07/2009 07:27 PM, Iñaki Baz Castillo wrote:
2009/7/7 Daniel-Constantin Mierla miconda@gmail.com:
I use nat-traversal module and it's MUCH MUCH more powerful than nathelper, for sure.
I do not agree at all with this, when comes to flexibility. nat_traversal main problem is the relying on dialog module, which adds lot of overhead to a proxy.
Not sure now if dialog module is fully required for all the cases... It's just required if you want to mantain nat keepalive for calls initiated by non registered users.
it does not bind to usrloc, so I think it has no idea who is registered or not, unless it is done via some parameters.
For presence, like for registration, the keepalive should be done by the endpoint (registrar, presence server), otherwise you get into scalability issues.
Imagine a presence agent machine (behind NAT) subscribing to the presence of some users without registering.
First I think that is not a typical use case, but more than that, imagine you have 100 000 presence sessions spread across couple presence servers and about the same number of calls going through your proxy.
Do you think it will deals nicely doing pings? While for calls, nat pinhole is handled by the registrars, same can be done by the presence servers.
Architectural point of view, it is even better doing so, as once there is no reply, the presence dialog can be destroyed and resources freed on server side. With nat_traversal approach, you consume twice resources in the server side, as you keep dialog attributes on proxy and presence server, therefore you double the scalability issues.
How to mantain the keepalivee in Kamailio (without using nat_traversal module)? The dirty solution would be decrease the notification interval, that of course would be a wrong choice.
Why would be that more wrong than sending keepalives from a stateful proxy? See above, you keep the dialog only once on server side.
Cheers, Daniel