Oracle Communications Diameter Signaling Router (DSR)
 

PLA-Support>Sun Systems>CommsGBU>Global Signaling Solutions>SN-SND: Tekelec DSR
 

In this Document

Symptoms

Changes

Cause

Solution

References

Created from <SR 3-17306773390>

Applies to:

Symptoms

A Diameter peer node has SCTP connection to DSR. When the node or connection experiences abnormal interruption (e.g. node restarts), the association drops and after recovery attempts to re-establish the connection to DSR. The SCTP handshake is successful but Diameter connection fails on first attempt. The peer node retries to establish the connectivity and finally succeeds after one or more attempts.

Based on CEA from DSR back to the peer, the reason provided is unknown peer:

  "AVP: Error-Message(281) l=53 f=--- val=DCL-ERR-3010-001: Unknown or unexpected peer."

Peer node continues attempts to re-establish, sending identical (except for unique identifiers) CER and finally the connection recovers without any changes to either side.

Other elements of the problem signature:
 - little traffic on connection
 - no DPR received due to abnormal peer failure (restart)
 - Responder type connection
 - connection fails one or more tries, then succeeds with no config changes
 - CEA response with error 3010-001 Unknown or unexpected peer

Changes

 Peer or connection failed in a manner that does not issue DPR toward DSR.

Cause

This problem is likely due to a software bug in DSR 7.2-7.4, resolved in DSR 8.0 wherein on low-traffic connections SCTP does not inform the application that the peer has become unavailable so new handshake succeeds but CEx fails because no DPx exchange occurred.
 

Solution

Permanent solution is provided in DSR 8.0; recommend upgrading to that release or later.

Interim workaround is to increase frequency of Diameter Watchdog.  Default in the DSR is 30s; recommend 5s to address this problem.  This does not prevent the issue, but will allow connection recovery more quickly.  This change does not provide additional traffic burden since watchdog messages (DWR/A) are only exchanged when the connection is idle for the interval.  To make this change in the DSR, change to the Connection Configuration Set associated with the connection [Main Menu / Diameter / Configuration / Configuration Sets / Connection Configuration Sets | “Diameter Options” tab, “Watchdog Timer Init Value].  Alternatively, create a new ConnCfgSet using all the same values except this timer, then edit the value for the Connection’s Connection Config Set--Note: this may require disabling the connection to edit.

References

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