[SR-Users] [sr-dev] Testing SIP Outbound / RFC5626 (Was: Freezing for next major release)

[Richard Brady]

> Also can a flow fail temporarily?
>
> For example a broadband router with a NAT timeout of 60 seconds and a UA
> with a keep-alive interval of 120s. Would the flow succeed for the first 60
> seconds after each keep-alive and then fail for 60 seconds until the next
> keepalive?
>
> Yes. That's a misconfigured ua, isn't it...
>

Don't think so. It is not easy or common for UAs to discover the NAT
timeout. They must make assumptions about what is a reasonable lower bound,
unless you are mad enough to expect the user to configure this. On mobile /
battery-powered devices it is often not an option to configure a keep-alive
interval that low.

But if you want a different example then take an unreliable network
connection. My question was more about whether the EP would generate a 430
or a 408/503/504 in this kind of potentially temporary failure case.

The UA will have to make sure to manage connections properly so at least
> one of the two are always open and working...
>

Yes AND the proxy has to manage those flows properly so both of the two are
always tired when necessary and preferably not after a 32 second timeout
trying a flow which it should already know has failed.

Keep in mind the the flows are tried serially, not in parallel.


> Outbound is all about pushing responsiblity for the flows to the UA.
>

Responsibility for initiating them yes. But there is a whole lot for the
server to do and that is what we're trying to get to the bottom of.


> Well, Outbound is very focused on TCP. It's alive or dead. It doesn't
> behave like UDP.
>

So if the network flaps for 60 seconds is a TCP connection dead or alive?

Richard
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