Description

This article provides an explanation and possible cause for the following syslog message:

unexpected error interrupt, t5e_error_isr

Symptoms

On the T4000 platform with flexible PIC concentrator (FPC) Type 5-3D, when 10G PIC ( PF-12XGE-SFPP ) is replaced with 100G ( PF-1CGE-CFP ) physical interface card (PIC), the interfaces do not come up.

The following syslog entry might be seen: 

Jun  1 00:27:21  router_name fpc4 T5E(4/0): unexpected error interrupt, t5e_error_isr

T5E stands for Type 5 Ethernet driver used on the Physical Interface Card (PICs)  [ PF-12XGE-SFPP  and  PF-1CGE-CFP ] that can be used with  FPC Type 5-3D . 

Solution

Reboot FPC to clear the condition and allow the interfaces to come up. Refer to PR​1369168 for the recommended action for a permanent fix (releases with the fix).

To help verify if this is your issue, the following information can be gathered before taking any action.  This is a read action, so there should be no impact.  

start shell pfe network fpcX where X is the FPC number
bringup jspec read xmchip[0] register ethss 0 xxlce_misc rx_reset

Example: 

user@router_name > start shell pfe network fpc4
HCFPC platform (1200Mhz QorIQ P2020 processor, 2816MB memory, 512KB flash)
HCFPC4(router_name vty)#  bringup jspec read xmchip[0] register ethss 0 xxlce_misc rx_reset

0x0780c0a0  xm.ethss[0].xxlce_misc.rx_reset    00000FFF <-- If this is the value after placing the 100g PIC where the 10g PIC was, then you have hit the issue. The correct value should be all 0's when 100g PIC is in place. 

HCFPC4(router_name vty)# exit