Which protocol utilizes a Designated Router on broadcast networks?

The protocol that utilizes a Designated Router on broadcast networks is OSPF, which stands for Open Shortest Path First. In OSPF, when routers are connected to a broadcast network, such as an Ethernet segment, one router is elected as the Designated Router (DR). The role of the DR is crucial in minimizing the number of adjacencies and the amount of routing protocol traffic over the network segment.

The Designated Router collects and distributes link-state information to other OSPF routers in the same broadcast network, thus optimizing the process of sharing routing information. This election process helps in reducing the overhead associated with OSPF communications, as it limits the number of routers that need to send full link-state updates to every other router. When changes occur in the network, only the DR and a Backup Designated Router (BDR) will handle the LSAs (Link-State Advertisements), making the process more efficient.

Other protocols listed do not employ a Designated Router on broadcast networks. For instance, ICMP (Internet Control Message Protocol) is mainly used for error reporting and does not establish neighbor relationships like OSPF. EIGRP (Enhanced Interior Gateway Routing Protocol) and BGP (Border Gateway Protocol) also do not