This article discussing the command "show chassis fabric degraded-fabric-reachability" on PTX EVO routers and how to identify the current state of reachability between the Packet Forwarding Engines

Model: ptx10008

Junos: 23.4R2.14-EVO

root@labrouter-re0> show chassis fabric degraded-fabric-reachability

..

Degraded Fabric reachability Information:

FPC #0

  PFE #0

   SIB0_Plane0

     Link errors FPC/PFEs 1/8

   SIB0_Plane1

     Link errors FPC/PFEs 1/8

   SIB0_Plane2

     Link errors FPC/PFEs 1/8

     ...

FPC #1

  PFE #0

   SIB0_Plane0

     Link errors FPC/PFEs 1/8

   SIB0_Plane1

     Link errors FPC/PFEs 1/8

     ...

  PFE #8

   SIB0_Plane0

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB0_Plane1

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB0_Plane2

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB0_Plane3

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB0_Plane4

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB0_Plane5

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB1_Plane6

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB1_Plane7

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB1_Plane8

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB1_Plane9

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB1_Plane10

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB1_Plane11

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB2_Plane12

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB2_Plane13

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB2_Plane14

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB2_Plane15

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB2_Plane16

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB2_Plane17

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB3_Plane18

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB3_Plane19

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB3_Plane20

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB3_Plane21

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB3_Plane22

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB3_Plane23

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB4_Plane24

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB4_Plane25

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB4_Plane26

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB4_Plane27

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB4_Plane28

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB4_Plane29

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB5_Plane30

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB5_Plane31

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB5_Plane32

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB5_Plane33

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB5_Plane34

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

   SIB5_Plane35

     Link errors FPC/PFEs 0/0 0/1 0/2 0/3 0/4 0/5 0/6 0/7 0/8 1/0

             1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 2/0 2/1

             2/2 2/3 2/4 2/5 2/6 2/7 2/8 3/0 3/1 3/2

             3/3 3/4 3/5 3/6 3/7 3/8 7/0 7/1 7/2 7/3

             7/4 7/5 7/6 7/7 7/8

The command "show chassis fabric degraded-fabric-reachability" was crucial to confirm that all FPCs are reporting issues specifically related to FPC1 PFE8.

To address this, we performed a reboot of FPC1, which appears to have cleared the errors.