> 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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