This article describes a reason of service PIC reset due to prolonged flow-control in Dual-Stack Lite (DS-Lite) scenario

If prefix-based DS-Lite config is in place in service-set as:

softwire-options { 

 dslite-ipv6-prefix-length <prefix lentgh>;

}

and high rate of traffic within a given DS-Lite tunnel comes to the box, transient flow control may be triggerred by service PIC. This will be reflected in logs as:

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 0 for 3 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 1 for 3 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 2 for 3 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 3 for 3 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 0 for 4 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 1 for 4 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 2 for 4 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 3 for 4 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 0 for 5 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 1 for 5 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 2 for 5 seconds 

fpc0 ms-0/0: Transient flow-control asserted by XLP MAC over link 3 for 5 seconds

If transient flow control takes more than 5 seconds, software considers it as a prolonged flow control. Prolonged flow control event triggers service PIC restart:

fpc0 Prolonged flow-control asserted by MAC on ms-0/0, bringing interface down 

fpc0 ms-0/0: MAC stuck, trigger coredump via nmi 

If dump-on-flow-control is configured for corresponding PIC as:

  pc-0/0/0 {

    multiservice-options {

      flow-control-options {

        dump-on-flow-control;        

      }

    }

  }

 mspmand core file will be created and visible in router's CLI as:

user@router> show system core-dumps no-forwarding

/var/crash/*core*: No such file or directory

-rw-rw---- 1 nobody wheel 819190917 Oct 11 21:42 /var/tmp/pics/mspmand.core.ms00.0.gz

/var/crash/kernel.*: No such file or directory

/var/jails/rest-api/tmp/*core*: No such file or directory

/tftpboot/corefiles/*core*: No such file or directory

total files: 1

The problem has been fixed in the following Junos releases 
22.4R3 - 23.1R2 - 23.2R2 - 23.3R1 - 22.1R3-S4 - 22.3R3-S1 - 21.3R3-S5 - 23.4 - 21.2R3-S7 - 22.2R3-S3 - 22.4R2-S2 - 21.4R3-S5 - 23.2R1-S2
To confirm your issue is matching the described symptoms, it's always recommended to open JTAC case.

2024-11-20 : Modifications to make KB public
2024-10-14 : Article Created