BDR
In
OSPF (Open Shortest Path First), the system elects a designated router (DR) and a BDR. The BDR smooths
the transition to the DR, and each multi-access network has a BDR. The BDR is adjacent to
all routers on the network and becomes the DR when the previous DR fails. The period of
disruption in transit traffic lasts only as long as it takes to flood the new LSAs (which
announce the new DR). The BDR is elected by the protocol; each hello packet has a field that
specifies the BDR for the network.