Elements of OSPF Routing 7-9
Interface
Characteristics
You configure OSPF router interfaces by adding OSPF characteristics to
existing IP Virtual LAN (VLAN) interfaces. See Chapter 9, “Administering
VLANs,” for information about how to configure VLAN interfaces.
The OSPF interface has the following characteristics and statistics, which
are discussed in the next sections:
■ Mode
■ Priority
■ Area ID
■ Cost
■ Delay
■ Hello Timer
■ Retransmit Timer
■ Dead Interval
■ Password
Mode
The mode for an interface can be off or active. To run OSPF routing on
the interface, set the mode to active.
To set the OSPF interface mode to active, you must enable IP routing. See
Chapter 10 for information about enabling IP routing.
Default The default mode is off.
Priority
You assign the interface priority to an OSPF router to determine its status
as a designated router. A router can function in one of three ways:
■ Designated router (DR) — The router with the highest priority value,
unless a designated router already exists on the network segment.
■ Backup designated router (BDR) — The router with a lower priority
than the DR; the BDR takes over DR functions if the DR fails.
■ Not a designated router — Any router given a priority 0 or not
elected DR or BDR. Priority 0 routers can never be elected as a DR or
a BDR.
Default The default priority value is 1.
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