Zone TypesOSPFv3 supports different zone types depending on the requirements of a network. These areas are: Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay Normal Zone: The Normal Zone, also called Normal Zone, connects to the Primary Zone through one or more Zone Border Routers. The Link State Announcement (LSA) types that are exchanged between a normal zone and the base zone are inter-area-prefix LSAs and AS external LSAs. ASBRs are used in normal areas. Stub Zone: To reduce the amount of external routing information flooded into a zone, this zone can be configured as a stub zone. A stub zone also connects to the base zone of autonomous systems via one or more ABRs, but does not allow the use of internal ASBRs and the flooding of external AS LSAs, since these LSAs are normally flooded in the entire autonomous system to broadcast external route information. A stub zone uses the inter-zone-prefix LSA as the default route for all routing information that must be transmitted through the base zone to the external autonomous system. For IPv6, the prefix length of this LSA is set to 0. Not–So–Stubby–Area (NSSA): NSSA is like a stub area. However, in an NSSA, the ASBR is used to authorize external routes from the autonomous system to an NSSA using redistribution. The ASBR redistributes external routes and then generates Type 7 LSAs which are flooded within the NSSA. In the NSSA, LSA Type 5 is not permitted. However, an ABR can optionally be configured to connect the NSSA to other areas to convert Type 7 LSAs to Type 5 LSAs and then flood these converted LSAs throughout the autonomous system (Cisco.com, 2016). Designated Router (DR) and Backup Designated Router (BDR) Different types of networks present OSPF with a unique challenge to manage. A network can be point-to-point or a multi-access network providing shared media for multiple routers to communicate. In a multi-access network, if every router floods the network with LSAs, the same information about the state of a link will be transmitted from multiple sources, resulting in significant CPU load and bandwidth consumption of the router . In a multi-access network, OSPF uses a single router called a designated router (DR) to control how LSAs are flooded. The goal of using DR is to minimize the number of adjacencies formed so that all router topology tables can be synchronized. A backup designated router (BDR) is an automatic backup router for the DR in the same network type. The BDR receives LSA packets and routing updates from adjacent OSPF routers but does not flood LSA updates. BDR only works if DR fails. Each router in a multi-access network establishes an adjacency with the DR and BDR.