4 Feb
2014
4 Feb
'14
12:58 p.m.
On 02/04/2014 12:54 PM, Olle E. Johansson wrote:
And you assume a lot of things - that your invites are
sent to the same
server, which may not be the case. DNS lookups and load balancing/failover
is done on a per transaction basis.
In fairness, RFC 3578 does offer a fair bit of commentary on this caveat:
However, having subsequent INVITEs routed in different ways brings
some problems as well. The first INVITE, for instance, might be
routed to a particular gateway, and a subsequent INVITE, to another.
The result is that both gateways generate an IAM. Since one of the
IAMs (or both) has an incomplete number, it would fail, having
already consumed PSTN resources.
[...]
Routing in SIP can be controlled by the administrator of the network.
Therefore, a gateway can be configured to generate SIP overlap
signalling in the way described below only if the SIP routing
infrastructure ensures that INVITEs will only reach one gateway.
When the routing infrastructure is not under the control of the
administrator of the gateway, the procedures of Section 2 have to be
used instead.
And, while I agree that this is ridiculous and is in conflict with the
basic spirit of SIP, somehow 3578 did become an RFC... I am as puzzled
by that as you may be. :-)
-- Alex
--
Alex Balashov - Principal
Evariste Systems LLC
235 E Ponce de Leon Ave
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