This article explains how to troubleshoot and resolve the alarm "Loss of communication with backup RE".

We might be seeing the below alarm and log messages, when the RE0 goes to PRESENT state and RE1 becomes master RE.

> show chassis alarms no-forwarding

1 alarms currently active

Alarm time       Class Description

2024-08-11 02:08:44 ICT Minor Loss of communication with Backup RE

> show chassis routing-engine no-forwarding

Routing Engine status:

 Slot 0:

  Current state         Present

> show chassis environment no-forwarding

Class Item             Status  Measurement

Temp 

   Routing Engine 0       Present

   Routing Engine 0 CPU     Present

We could see the master RE has lost the keep-alives messages from the backup and the ‘Loss of communication with Backup RE0’ appearing below:

Aug 11 02:08:35 MX104_RE1 chassisd[1981]: No response from the other routing engine for the last 2 seconds.

Aug 11 02:08:35 MX104_RE1 chassisd[1981]: CHASSISD_SNMP_TRAP10: SNMP trap generated: Fru Offline (jnxFruContentsIndex 9, jnxFruL1Index 1, jnxFruL2Index 0, jnxFruL3Index 0, jnxFruName Routing Engine 0, jnxFruType 6, jnxFruSlot 0, jnxFruOfflineReason 2, jnxFruLastPowerOff 0, jnxFruLastPowerOn 1895981216)

Aug 11 02:08:38 MX104_RE1 /kernel: tcp_timer_keep: Dropping socket connection due to keepalive timer expiration, idle/intvl/cnt: 1000/1000/5

Aug 11 02:08:38 MX104_RE1 /kernel: tcp_timer_keep:Local(0x80000001:6234) Foreign(0x80000006:55708)

Aug 11 02:08:44 MX104_RE1 alarmd[2289]: Alarm set: RE color=YELLOW, class=CHASSIS, reason=Loss of communication with Backup RE

Aug 11 02:08:44 MX104_RE1 craftd[1984]: Minor alarm set, Loss of communication with Backup RE

Aug 11 02:14:38 MX104_RE1 chassisd[1981]: No response from the other routing engine for the last 360 seconds.

Aug 11 02:20:42 MX104_RE1 chassisd[1981]: No response from the other routing engine for the last 360 seconds.

Aug 11 02:26:45 MX104_RE1 chassisd[1981]: No response from the other routing engine for the last 360 seconds.

Recommendation (to be performed during the MW time):

• Try restarting the routing-engine 0 via CLI.
  • From RE1: > request system reboot other-routing-engine (or)
  • From RE1: > request vmhost reboot other-routing-engine  (if vmhost)

• If that doesn’t work, then we may need to restart the CB0 and see if the RE0 comes online. 

• From RE1: > request system halt other-routing-engine (or)
• From RE1: > request system power-off other-routing-engine (if vmhost)
• From RE1: > request chassis cb slot 0 offline
• From RE1: > request chassis cb slot 0 online

• If restarting CB0 also doesn’t work, then we may try connecting a spare RE & spare CB on the slot 0 (if available) to confirm, if the RE/CB is faulty.