Default Settings
22-16 Configuring OSPFv2
Configuring OSPF Interface Timers
The following OSPF timers are configured at the interface level in interface configuration mode:
•Hello Interval
•Dead Interval
•Retransmit Interval
•Transmit Delay
Use the hello interval (ip ospf hello-interval) and dead interval (ip ospf dead-interval) timers to
ensure efficient adjacency between OSPF neighbors. The hello interval is the period between
transmissions of hello packet advertisements. The dead interval is the period that can elapse
without receiving a router’s hello packets before its neighbors will declare it down.
In order to ensure that flooding is reliable, LSAs are retransmitted until they are acknowledged.
The period between retransmissions is the retransmit interval (ip ospf retransmit-interval). If this
interval is set too low for an interface, needless retransmissions will take place. If the value is set
too high, the speed of the flooding, during the period of lost packets, may be affected.
The transmit delay is an estimation of the number of seconds it takes to transmit a link state
update packet over this interface. This value should take into account transmission and
propagation delays. Configure this timer with the ip ospf transmit-delay command.
These OSPF timers can also be configured for an area virtual-link. See “Configuring Area Virtual-
Links” on page 22-12. Also refer to “Configuring SPF Timers” on page 22-7 for a description of the
router level timers that you can configure.
Default Settings
Table 22-1 lists OSPF parameters and their default values.
Table 22-1 Default OSPF Parameters
Parameter Description Default Value
OSPF process Status of the protocol, whether
enabled or disabled.
Disabled globally and per interface
router ID Provides for the identification of one
router to another and helps establish
adjacencies among OSPF routers.
highest IP address of configured
routing interfaces
interface cost An outbound interface value used in
determining which routing interface
should forward when more than one
routing interface is available.
10
interface priority A value placed on the interface that
helps in determining which router will
be elected designated router.
1
SPF delay timer Specifies the amount of time between
receiving an OSPF update and the
start of an SPF calculation.
5 seconds
SFP hold time Specifies the minimum amount of time,
in seconds, between two consecutive
OSPF calculations.
10 seconds
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