# Double-Bit Errors on SRP Modules

SRP modules include error checking and correction (ECC) to protect their SDRAM. ECC provides error detection of single-bit and double-bit errors and correction of single-bit errors for the SDRAM as follows:

- If ECC detects a single-bit error, it automatically corrects the error, and operation continues.
- If ECC detects a double-bit error, it logs the error, stops the main processor on the controller, and takes the SRP module offline.

## Detecting Double-Bit Errors

The following message appears on the console if ECC detects a double-bit error:

    ALERT 05/10/2000 13:10:33 os: failed: ECC DOUBLE BIT ERROR OCCURRED
      Address = 0xe95db10
      Data (Upper 32Bits) = 0xe95db20
      Data (Lower 32Bits) = 0x55d06c
      ECC Data Bits =  0x2b
      ECC 1Bit Error Counter =  0x0
      *** YOU MUST PERFORM A HARD RESET TO CONTINUE ***
    ALERT 05/10/2000 13:10:34 os: PROCESSOR EXCEPTION: 0x200n

If ECC detects a double-bit error in a system that contains a redundant SRP module, the redundant module becomes active and the system continues to operate. However, you must still troubleshoot the SRP module with the double-bit error. When ECC detects a double-bit error in a system that does not contain a redundant SRP module, you must troubleshoot the SRP module immediately. See Fixing Double-Bit Errors.

## Fixing Double-Bit Errors

To fix a double-bit error:

1. Remove the second SRP module, if there is one.
2. Reboot the system with the module reset button on the primary SRP module. (See Figure 9.)

These actions attempt to correct a transient double-bit error. However, if the console displays a memory test failure for the SRP module after you reboot, or if the FAIL LED on the SRP module stays on during rebooting, the SDRAM is permanently damaged and needs replacing. In this event, call Juniper Networks Customer Service to arrange for repair.