There are three principal network topologies that should be considered when choosing a routing protocol to pair with them to avoid misconfiguration or sub-optimal routing behavior.
Point-to-Point: Simplest type of topology to configure. Connects a single pair of routers, where traffic is transmitted exclusively on a 1:1 basis. Traffic sent from one end of the link is received by the remote device at the other side.
Broadcast Network: Connects several nodes with the capability of sending traffic to all attached devices. Can broadcast a single packet. Ethernet is an example of a broadcast network, and WAN technologies today are typically deployed as this type.
NBMA: A Non-broadcast, Multiple Access network is somewhat similar to a broadcast network with the exception that it does not allow for broadcasted traffic; it connects several devices together. To send to all connected devices, the sender must replicate the packet for each destination device, and source and destination addressing must be mapped together. A traditional example is frame-relay.
Treating or emulating a WAN as a broadcast network type can have severe repercussions if routing protocol configurations are not considered carefully.
NBMA networks demonstrate challenges that require how the routing protocols is configured. For instance, the nature of NBMA can negatively impact normal neighbor discovery processes and must be accounted for. Similarly, distance vector protocols require special circumstances if multiple “spokes” on an NBMA topology attempt to share data via a single “hub” interface, due to split horizon rules which maintain that a device cannot transmit information out the same interface where it was already received.
Stuck-in-Active: Journal of an IT-Network Administrator 