This chapter describes the Idle Timeout Handling feature for S-GW sessions. On the ASR5500 platform, subscriber session is represented by call-line. The S-GW product call-line interfaces to its peers through MME/S4-SGSN on S11/S4 and P-GW on S5/S8. In some scenarios, peer sessions are deleted by respective peers, S-GW does not receive or miss deletion messages, and as a result S-GW session remains idle. Such idle or stale sessions are counted towards valid call-lines in system for effectively consuming resources and causing capacity reduction. In such cases, S-GW triggers to get the new subscriber session, which results in the removal of old session for same subscriber. The Idle Timeout Handling support enables the identification of such sessions and initiates deletion to release the resources.

The following points describes the idle timeout handling for S-GW sessions:

• The subscriber session is idle when there is no data traffic activity for the subscriber. The session manager keeps track of the call-line state, when no data traffic is recorded for call-line, such sessions are moved to idle state.

• Session which is idle for defined timeframe referred as idle timeout is considered for idle timeout handling. In idle timeout session, S-GW initiates the deletion of session towards its peers.

• Idle timeout is configured in seconds depending on the network requirements. The timeout range is 1-4294967295 seconds.

• The idle timeout configuration is applicable on S-GW service level for enabling the idle timeout handling for set of subscribers handled by that service.

The session idle timer for S-GW sessions is configurable from S-GW service.

To configure Session Idle Timeout for S-GW, use the following configuration:

configure 
   context context_name 
      sgw-service service_name 
         [ no | default] timeout idle timeout_duration 
         end 

NOTES:

• timeout idle timeout_duration : Specifies the maximum duration a session can remain idle for, in seconds, before the system automatically terminates the session. timeout_duration must be an integer in the range of 1-4294967295. 0 disables the feature. By default, it is disabled for the S-GW service.