Chapter 8: AI2524 Protocol Configuration Steps
August 1997 Page 8-9
2524UM
Configure Route Calculation TimersYou can configure the delay time between when OSPF receives a to-
pology change and when it starts a Shortest Path First (SPF) calcula-
tion. You can also configure the hold time between two consecutive
SPF calculations. Type this command in router c on fi g ura tion mode:
timers spf
spf-delay spf-holdtime
The OSPF on-demand circuit is an enhancement to the OSPF protocol
that allows efficient operation over on-demand circuits like ISDN,
X.25 SVCs, and dial-up lines. This feature supports RFC 1793, ex-
tending OSPF to Support Demand Ci rcuits.
With this feature, periodic hellos are suppressed and the periodic re-
freshes of LSAs are not flooded over the demand circuit.
To configure OSPF for on-demand circuits, per form these tasks:
1. Enable OSPF operation.
router ospf
process-id
2. Configure OSPF on an on-demand circuit.
ip ospf demand-circuit
If the router is part of a point-to-point topology, then only one end of
the demand circuit must be configured with this command. However,
all routers must have this feature loaded.
If the router is part of a point-to-multipoint topology, only the multi-
point end must be configured with this command.
Implementation Considerations
Because LSAs that include topology changes are flooded over an on-
demand circuit, it is advised to put demand circuits within OSPF.