| Asset ID: |
1-72-2395700.1 |
| Update Date: | 2018-05-10 |
| Keywords: | |
Solution Type
Problem Resolution Sure
Solution
2395700.1
:
DSR STCP Multihomed Connection Remains Up Even After Number Of Maximum Retransmissions for Connection Is Crossed
| Related Items |
- Oracle Communications Diameter Signaling Router (DSR)
|
| Related Categories |
- PLA-Support>Sun Systems>CommsGBU>Global Signaling Solutions>SN-SND: Tekelec DSR
|
In this Document
Created from <SR 3-17346835211>
Applies to:
Oracle Communications Diameter Signaling Router (DSR) - Version DSR 5.0 and later
Tekelec
Symptoms
Multihomed sctp diameter connection is not dropped while the Number of Retransmits Triggering Association Failure set to 10 is crossed.
Changes
Cause
System is performing as per RFC 4960 SCTP
Referring to the RFC 4960 Section 8.2 - Path Failure Detection:
The counter for path failure is incremented when the HeartBeat fails. In this case, HB keep continuing so "Path.Max.Retrans" parameter is not incremented and hence the path remains open.
Solution
Taking following example of messages:
chunk 4697 sent by primarylocIP with TSN 1559252083
chunk 4700 is SACK for TSN 1559252083
chunk 4703 sent by primarylocIP with TSN 1559252084
chunk 4704 sent by primarylocIP with TSN 1559252085
chunk 4707 is SACK for TSN 1559252083 with GAP 1 --> this means that upto 1559252083 all packets have been received at far end but next packet (1559252084) is not recieved and one following it (1559252084) has been received
chunk 4709 is retransmitted by primarylocIP with TSN 1559252084
There is never acknowledgement received for TSN 1559252084
During this time, and after that, there are continuous HB and HB-ACK in both directions on this path.
Also, there is continuous traffic flowing from far end to local end as well.
As the HB/HB-ACK is successful, hence the path failure condition is never triggered and the path remains available as normal.
This is normal functionality.
Referring to the RFC 4960 Section 8.2 - Path Failure Detection: The counter for path failure is incremented when the HB fails. In this case, heartbeats keep continuing so "Path.Max.Retrans" parameter is not incremented and hence the path remains open.
Conclusion:
As heartbeats are successful on this path, hence path is not taken down.
On both paths, only last message of a fragmented message is acknowledged by far end. So need to see how the far end receives the fragmented messages and how it reassembles them.
Attachments
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