What is the best way to determine if the current IP address belongs to fxp0 or a Routing Engine, from a CLI session?
Routing Engines are mapped with the fxp0 interface. This means that when you query RE0, the ifTable reports the fxp0 interface address of RE0 only.
Similarly, if you query RE1, the ifTable reports the fxp0 interface address of RE1 only.
For more information, click Configuring SNMP on devices running Junos OS.