This article addresses the case where a Flexible PIC Concentrator (FPC) and/or Dense Port Concentrator (DPC) reboot occurs, and a core dump containing the backtrace item ddr_sdram_periodic is generated. If SDRAM errors appear in the NVRAM output, then this is most likely a hardware issue. An RMA is recommended.
An FPC/DPC rebooted and generated a core dump. The backtrace of the core dump has ddr_sdram_periodic as one of the elements of the back trace.
In this case, the FPC/DPC restart was likely due to ECC errors in the SDRAM of the board.
Check the NVRAM output for the FPC that rebooted.
> start shell pfe network fpc0 fpc0> show nvram [Feb 11 05:01:31.006 LOG: Emergency] <160>Last Detected DDR SDRAM Error: at addr 0x401929a0, data 0x8421ffe893a1000c [Feb 11 05:02:02.005 LOG: Emergency] <160>Last Detected DDR SDRAM Error: at addr 0x0, data 0x0000000000000000 [Apr 1 22:08:51.005 LOG: Emergency] <160>Last Detected DDR SDRAM Error: at addr 0x401929a8, data 0x8421ffe893a1000c [Apr 1 22:09:22.002 LOG: Emergency] <160>Last Detected DDR SDRAM Error: at addr 0x0, data 0x0000000000000000
If you see SDRAM Errors in the NVRAM output, then this is most likely a hardware issue and an RMA is recommended.