
Explanation:
* It's important the RP address is NOT the loopback address but one of the other address in the subnet defined on the loopback
* By default, OSPF advertises all loopbacks as /32 so the need of 'ip ospf network point-to-point' command to advertise the subnet mask
* We hardcode the OSPF RID to avoid any duplicate RID problem in case address of Loopback1 is the highest loopback
* There is a need to define a mapping agent for auto-rp to work (not shown here)
* BSR doesn't support yet the possibility to advertise as candidate RP an IP address which is not defined on any interface. This implies that BSR cannot be used with phantom RP. We need to use either Auto-RP or static RP.