[asterisk-dev] STUN support in chan_sip revisited

[Kevin P. Fleming]

On 08/09/2010 09:14 AM, Olle E. Johansson wrote:
> 
> 9 aug 2010 kl. 15.24 skrev Klaus Darilion:
> 
>>
>>
>> Am 09.08.2010 14:11, schrieb Simon Perreault:
>>>> Thus Asterisk would need
>>>> a feature to send REGISTERs with the required high Expires header, but
>>>> reregisters much earlier although the registration has not expired.
>>>
>>> Yes!
>>>
>>> And note that this is 100% compliant with RFC 3261. The only purpose of
>>> the Expires header returned by the registrar is to inform the client of
>>> the registration's life-time. The client is free to re-register (or not)
>>> at any moment.
>>>
>>> The right value for the Expires header to be sent to the registrar could
>>> be determined automatically from the Min-Expires header that the
>>> registrar sends us when it rejects the initial REGISTER with a 423
>>> (Interval Too Brief). Asterisk would send a new REGISTER request with
>>> this value but the actual re-registration interval would be the one
>>> configured statically in sip.conf. Would that work?
>>
>> I think yes. But IMO it is not elegant - using STUN or CRLF is more 
>> elegant. Although not defined in RFC3261, CRLF as keep-alive for UDP is 
>> well supported.
>>
> Adding REGISTER requests might add database lookups and load on 
> the registrar server, which is not kindly seen...
> 
> In this discussion we really need to separate Asterisk as a UA, connecting to services and Asterisk as a server - otherwise it gets too confusing for everyone.

Asterisk is always a SIP UA, since all endpoints that implement SIP are
UAs :-)

Now, to answer your question more properly, the discussion at this point
is entirely about Asterisk as a consumer of services provided by a
provider, with the Asterisk system located behind a NAT and the
provider's system on a public IP address (it may also be behind a NAT,
but if so it would have been statically mapped to be transparent).

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
skype: kpfleming | jabber: kfleming at digium.com
Check us out at www.digium.com & www.asterisk.org