Bier edge router       Bier edge router 
          |--PIM domain--|--BIER domain (PLI)--|--PIM domain--| 
Source--( A )----------( B ) ---- ( C ) ---- ( D )----------( E )--Host
          |       PIM Adj|         | |         |PIM Adj       |
          |------------( E )-------| |-------( F )------------|
                                         (DR election)