In bidirectional mode, traffic is routed only along a bidirectional shared tree that is rooted at the rendezvous point (RP) for the group. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_pim/configuration/xe-16/imc-pim-xe-16- book/imc-tech-oview.html#GUID-51D0D6DF-E7F1-4A0E-8E31-D7ED464DF2AC