[standards-jig] VoIP, JEP-0065 and UDP?

Richard Dobson richard at dobson-i.net
Mon Jan 26 14:42:47 UTC 2004


> In that case it is impossible to transfer datagrams without proxy.
> Using proxy just to help both sides exchange their addresses doesn't
> help either.
>
> Let's consider an example:
> A--NAT---PROXY---NAT--B
> - A sends a UDP to PROXY
> - B sends a UDP to PROXY
> - proxy replies, giving B the address and port of A
> - proxy replies, giving A the address and port of B
>
> In ideal world, A and B would now be able to exchange datagrams,
> however, a typical NAT will check the source address of
> incoming datagram against the mapping (it mapped the port to PROXY
> address), and it just won't let it through.

There are other ways and means, using UPnP (or other such firewall control
protocols) for example which a majority of ADSL routers now come with these
days.

> So we *do* have to send datagrams through proxy.
> The question remains - is there a need in the Jabber community
> of decribing the negotiation with UDP proxy and putting it into a JEP?

Personally I think it would help to have a UDP proxy JEP like JEP-0065, but
remember that you must not rely on the proxy being available as I would
expect only companies would install such devices, I highly doubt ISP's or
server admins would install them due to the bandwidth requirements, so as I
say make sure you remember to try every possible way (e.g. UPnP) before
falling back to a proxy as I doubt very many of these proxies will be around
to use in the real world.

Richard




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