no explicit preference configured. By default lower router-id should be preferred. PE-CE @site 1 is using vlan 949 and PE-CE @site 2 is using vlan 950. Therefore, vlan mapping is used to connect them.

rwibawa@vmx-13-14# show routing-instances VLDP1 instance-type vpls; interface ge-0/0/0.542; protocols { vpls { interface ge-0/0/0.542; no-tunnel-services; vpls-id 502; mesh-group HUB { local-switching ...