ospf nbma and broadcast...

http://ardenpackeer.com/tutorials/routeswitch/tutorial-ospf-network-types-and-frame-relay-part-1/

this is an excellent tutorial to go through... the summary follows, which means little or nothing until you get through it... pay particular attention to the verification with the timers to prove the type of network that is being created...

i will not attempt to re-present something in my own hand that i cannot add to in some meaningful way... this is perfect and needs no embellishment... so turn to and get it done..

• Non-Broadcast network type is the default on a physical serial interface with ospf configured
• Non-Broadcast networks send unicast packets, so must be configured with neighbor statements
• Non-Broadcast networks have Hello and Dead intervals of 30 seconds and 120 seconds respectively
• Broadcast network types is the default on an ethernet interface.
• Broadcast network types must support broadcasting capability on a layer 2 topology
• Non-Broadcast and Broadcast network types require a DR. Care should be taken in DR placement (should be the Hub).

if you are like me, you simply wish frame relay would go away... the sad reality is that it has little use in modern production networks, but its idiosyncrasies are exploited to great effect by cisco to make your R&S life difficult...

the only solution is to bite the bullet and turn it on its end in your favor... for someone like me, that means beating the shit out of it...