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Create two loopback interfaces on juniper MX router

January 23, 2016 Roman Romanyak

In Junos it is not possible to create two Loopback interfaces in one routing instance, so the configuration example below would be invalid:

root@router# show interfaces lo0
unit 0 {
    family inet {
        address 10.1.1.1/32;
    }
}
unit 1 {
    family inet {
        address 10.1.1.2/32;
    }
}

[edit]
root@ny-edge-r1# commit check
[edit interfaces lo0]
  'unit 1'
    if_instance: Multiple loopback interfaces not permitted in master routing instance
error: configuration check-out failed

[edit]
root@router#

Instead, we have to create a separate routing instance, create Loopback interface there, and import a direct route of the second loopback to the main routing instance inet.0:

root@router> show configuration interfaces lo0 
unit 0 {
    family inet {
        address 10.1.1.1/32;
    }
}
unit 2 {
    family inet {
        address 10.1.1.2/32;
    }
}
------------------------------------------------------------------------------------------
root@router> show configuration routing-options 
interface-routes {
    rib-group inet GROUP1;
}
rib-groups {                            
    GROUP1 {
        import-rib [ RI01.inet.0 inet.0 ];
        import-policy LO2-2-INET;
    }
}
------------------------------------------------------------------------------------------

root@router> show configuration policy-options policy-statement LO2-2-INET                  
term 10 {
    from instance RI01;
    then accept;
}
term 100 {
    then reject;
}

------------------------------------------------------------------------------------------

root@router> show configuration routing-instances 
RI01 {
    instance-type virtual-router;
    interface lo0.2;
    routing-options {
        interface-routes {
            rib-group inet GROUP1;
        }
    }
}
  