DIAMETER: Once a Diameter session is established, how long a Diameter session exist ?

Question

I know Diameter client can re-transmit the request message until it receives the answer message.
But what about when a Diameter node has sent answer message to the last received request from its peer and that's is not received but its peer. In this case, from Diameter client node transaction is not completed since it did not receive answer message but from other node point of view it has responded with answer and transaction is completed.

Answer 1

Till it is terminated :)

Typically the client (which initiated the session) would terminate the session. In Gx, Gy, 4006 etc, CCR-T would be used to terminate. But server can also decide to terminate by sending ASR. But unlike a Diameter connection which is between two peers and failures can be detected by TCP or through Diameter watchdog, it is not easy to detect client or server failures. So a server may have a time-out to kill inactive sessions. In some applications (Gx. Gy), Reauth requests are used to force client to respond, so if RAR fails, server may initiate termination.

Note that Diameter sessions may live over long periods - say, you are not mobile and are running apps on your phone. Corresponding Gx or Gy sessions will persist for hours.

Answer 2

Hi Harshita,

From RFC-6733 Section - 8 it has mentioned like "When a Diameter server authorizes a user to implement network resources for a finite amount of time, and it is willing to extend the authorization via a future request, it MUST add the Authorization- Lifetime AVP to the answer message. The Authorization-Lifetime AVP defines the maximum number of seconds a user MAY make use of the resources before another authorization request is expected by the server. The Auth-Grace-Period AVP contains the number of seconds following the expiration of the Authorization-Lifetime, after which the server will release all state information related to the user's session."

If my understanding is correct , I think that is what you are looking for.

Thanks