ea zero, and there are no paths between areas other than via area zero. This is a proper OSPF network design. Area zero does not have to be fully meshed when you're using technologies such as Frame Relay. This is in part because OSPF recognizes the fact that there are different types of networks. OSPF knows that networks supporting broadcasts act differently from networks that are point-to-point and thus have only two active IP addresses. OSPF supports the following network types: Point-to-point A point-to-point network is one with only two nodes on it. A common example is a serial link between routers, such as a point-to-point T1. No DR is chosen in a point-to-point network, because there are only two routers on the network. This is the default OSPF network type on serial interfaces with PPP or HDLC encapsulation. Point-to-multipoint In a point-to-multipoint network, one hub router connects to all the other routers, but the other routers only connect to the hub router. Specifically, the remote Chapter 10: Routing Protocols routers are assumed to be connected with virtual circuits, though only one IP net- work is used. No neighbors are configured and no DR is chosen. Area 0 in Fig- ure 10-12 could be configured as a point-to-multipoint OSPF network. Broadcast A broadcast network is an Ethernet, Token Ring, or FDDI network. Any number of hosts may reside on a broadcast network, and any host may communicate di- rectly with any other host. A DR must be chosen and neighbors must be discovered or configured on a broadcast network. A broadcast network uses multicasts to send hello packets to discover OSPF routers. This is the default OSPF network type for Ethernet and Token Ring networks. Nonbroadcast multiaccess (NBMA) In a nonbroadcast multiaccess network, all nodes may be able to communicate with one another, but they do not share a single medium. Examples include Frame Relay, X.25, and Switched Multimegabit Data Service (SMDS) networks. Because NBMA networks do not use multicasts to discover neighbors, you must man