Network operators can monitor Ren 2 link status using Juniper’s CLI commands such as:
show chassis fabric plane
show fabric fpc
show log messages | match "ren"
Common issues include:
Log message:
RE 1: ren2 link state: Operational, but protocol negotiation failed
Cause: Different Junos versions between RE0 and RE1. The REN 2 protocol changed between 17.x and 21.x.
Solution: Upgrade both REs to the exact same Junos release (including the same build number). Use: juniper ren 2 link
request system software add /var/tmp/junos-sr-*.tgz re0
request system software add /var/tmp/junos-sr-*.tgz re1
Here is a real-world troubleshooting flowchart based on field experience.
Without GRES, the REN 2 link sits idle except for basic keepalives. Network operators can monitor Ren 2 link status
set chassis redundancy graceful-switchover
set chassis redundancy routing-engine 0 master
set chassis redundancy routing-engine 1 backup
commit
show log chassisd | match "ren"
This reveals the internal daemon logs. A healthy REN 2 link will show:
CHASSISD_RE_ETHERNET_UP: Ethernet link to RE1 is up