Description

This article provides the steps to troubleshoot a DPC/MPC (FPC) on an MX device that is reporting errors.

This series of steps is a subr outine that is called multiple times from KB23173 - Resolution Guide - Troubleshoot Fabric Plane [juniper.net] .

Solution

Perform the following steps for MX DPC/MPC Troubleshooting:

Note: For the flowchart version of these steps, click the flowchart icon:

alt

 

[Collect logs.]

  1. As a proactive step, collect logs on the MX router, in case they are needed later for diagnosing a problem. The logs to collect are detailed in KB22637 - [M, MX, T Routers] Data Collection Checklist [juniper.net] in the "MX Fabric Plane" section.

[Identify the FPC with errors.]

  1. In the output of " show chassis fabric plane ," which DPC (PFE) / MPC (PFE) has link errors?

Note: If you already identified the faulty DPC/MPC in KB23173 - Resolution Guide - Troubleshoot Fabric Plane [juniper.net] , then you can continue to Step 3 . 

user@router> show chassis fabric plane 
Fabric management PLANE state
Plane 0
  Plane state: ACTIVE
      FPC 0
          PFE 0 :Links ok
          PFE 1 :Links ok
          PFE 2 :Links ok
          PFE 3 :Links ok
      FPC 1
          PFE 0 :Links ok
          PFE 1 :Link error
      FPC 0
          PFE 0 :Links ok
          PFE 1 :Links ok
          PFE 2 :Links ok
          PFE 3 :Links ok

In the above example, Plane 0 is reporting an error on FPC1 (PFE1) (which is a type2 MPC card). Example outputs of a single plane reporting errors and multiple planes reporting errors are shown in KB23384 - Example outputs for Fabric reporting errors [juniper.net] .

Note: The number of PFEs under each FPC will vary according to the card type present in that slot. MPC type1 cards have one PFE. MPC type2 cards have 2 PFEs. MPC 16x10GE and DPC have 4 PFEs.

[Offline / Online the DPC with errors.]

  1. Offline and then Online the corresponding DPC/MPC, which is reporting errors (in Step 2).

CAUTION : It is strongly recommended to perform this step during a Maintenance Window, because turning off the line card will cause service impact in the interfaces related to the FPC. 

To Offline/Online a DPC/MPC, use " request chassis fpc slot <slot_no> offline|online ."

For more information about this command, refer to request chassis fpc .

Example: 

user@router> request chassis fpc slot <slot_no> offlineWait for few seconds and then do
user@router> request chassis fpc slot <slot_no> online

Continue to Step 4.

  1. Observe the outputs of " show chassis alarms " and " show chassis fabric planes ."

Has the link error reported in Step 2 been corrected, and are the alarms cleared (after performing Offline/Online of the DPC)?

[Re-seat the DPC/MPC with errors.]

  1. Physically re-seat the DPC/MPC. 

CAUTION : It is strongly recommended that you perform this step during a Maintenance Window, because turning off the line card will cause service impact in the interfaces related to the FPC. 

For guidelines, refer to the following:

Continue to Step 6.

  1. Observe the outputs of " show chassis alarms " and " show chassis fabric planes ."

Have the link errors and alarms been cleared (after re-seating the DPC/MPC)?

Modification History

2022-03-06: Article reviewed and updated to reflect current information