The preceding discussion on DRs and DISs makes it clear that both OSPF and IS-IS behave differently for different physical media. Understanding these differences is important not only for correctly designing your networks but also for troubleshooting problems on your network.
OSPF classifies all interfaces, physical or logical, into one of five network types:
Nonbroadcast multi-access (NBMA) networks
Broadcast networks might be more accurately named broadcast multi-access networks. More than two devices can connect to the network, and packets sent by one device can be seen by all connected devices. These days, broadcast ...