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[MX] Commit on backup RE may fail due to stale TCP connections between primary and backup RE



Article ID: KB36459 KB Last Updated: 01 Feb 2021Version: 1.0

Users may encounter commit operation failure on the backup Routing Engine (RE) when there are stale TCP sessions between the primary and backup RE. This article lists the Junos OS versions in which the issue has been resolved and also provides a workaround for short-term resolution of the problem.


  • Commit operation failing on the backup RE

  • Replicate errors LIBJNX_REPLICATE_RCP_ERROR reported in log message

  • Log message "rcmd: socket: Can't assign requested address" indicating that the backup RE cannot be assigned the internal address

  • Inability to log in to the backup RE via SSH or telnet into the FPCs



In rare cases, users may see the internal TCP connections build up between the primary and backup Routing Engine: 

Use show system connections on the primary RE to determine the stale connections. These stale connections can prevent the new internal TCP connections between the REs or the RE and FPC from coming up. Users may encounter issues with telnet to the FPC or commit / login to the backup RE due to these stale connections.



This issue is tracked through PR1394370.

The long-term fix is to upgrade the affected device to one of the following Junos OS versions in which the issue has been fixed: 18.2X75-D40, 18.2R1-S5, 18.2R2, 18.2X75-D30, 18.3R2, 18.4R1, 16.2R3, 17.2R1-S7, 17.4R2-S2, 15.1R8, 17.1R3, 16.1R7-S6, 17.2R3, 18.1R3-S2, 14.1X53-D53, 17.4R3, 17.3R3-S3, and 19.1R1.

As a short-term workaround, disable graceful Routing Engine switchover (GRES) and nonstop active routing (NSR), and re-enable them to see if the stale connections clear. If not, disable GRES and NSR, and then reboot the backup RE. When the backup RE comes up, re-enable GRES and NSR and check the status of the TCP connections by using show system connections.


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