In general, a separate copy of the OSPF protocol is run for each area. Because of this, most configuration parameters are defined on a per-area basis. The few global configuration parameters are listed below.
This is a 32-bit number that uniquely identifies the router in the Autonomous System. One algorithm for Router ID assignment is to choose the largest or smallest IP address assigned to the router. If a router's OSPF Router ID is changed, the router's OSPF software should be restarted before the new Router ID takes effect. Before restarting in order to change its Router ID, the router should flush its self-originated link state advertisements from the routing domain (see Section 14.1), or they will persist for up to MaxAge minutes.
This item indicates whether the router will calculate separate routes based on TOS. For more information, see Sections 4.5 and 16.9.