In case of using EX or QFX virtual chassis, 'Forward State' in ERPS will be unknown after rebooting or halting master FPC.

This KB describes the reason and provide a solution.

Before rebooting master FPC, both ring ports on master and backup FPC are 'forwarding' state.

{master:0}

root@switch> show protection-group ethernet-ring interface


Ethernet ring port parameters for protection group ERPS1


Interface Control Channel Direction Forward State RPL End SF   Admin State

xe-0/0/44 xe-0/0/44.0   east    forwarding   No    Clear IFF ready

xe-1/0/44 xe-1/0/44.0   west    forwarding   No    Clear IFF ready

After rebooting master FPC, forwarding state of new master FPC will be unknown instead of forwarding.

{master:1}

root@switch> protection-group ethernet-ring interface


Ethernet ring port parameters for protection group ERPS1


Interface Control Channel Direction Forward State RPL End SF   Admin State

Unknown  Unknown     east    Unknown    No    Clear waiting

xe-1/0/44 xe-1/0/44.0   west    Unknown    No    Clear IFL ready

This behavior is seen as expected when NSB(Nonstop bridging) is not enabled.
Enabling NSB for virtual chassis can help master and backup sync the state properly.

Because ERPS is using the same mechanism with STP, and NSB can help sync the l2 protocol session.

Here is the config to enable NSB.

set protocols layer2-control nonstop-bridging