Product guide

IP Routing Features
Configuring OSPF
Optional: Adjust Virtual Link Performance by Changing
the Interface Settings
The following OSPF interface parameters are automatically set to their default
values for virtual links. No change to the defaults is usually required unless
needed for specific network conditions. This is a subset of the parameters
described under “11. Optional: Adjust Performance by Changing the VLAN or
Subnet Interface Settings” on page 5-75. (The cost and priority settings are not
configurable for a virtual link, and the commands for reconfiguring the
settings are accessed in the router OSPF context instead of the VLAN context.)
Note The parameter settings described in this section for virtual links must be the
same on the ABRs at both ends of a given link.
Parameter Default Page
dead-interval 40 seconds below
hello-interval 10 seconds 5-86
retransmit-interval 5 seconds 5-86
transit-delay 1 second 5-87
Dead Interval on a Virtual Link.
Syntax: area < area-id > virtual link < ip-address > dead-interval < 1 - 65535 >
Used in the router OSPF context on both ABRs in a virtual link
to change the number of seconds that a neighbor router waits
for a hello packet from the specified interface before declaring
the interface “down”. This should be some multiple of the Hello
interval. The dead-interval setting must be the same on both
ABRs on a given virtual link.
< area-id >: Specifies the OSPF area in which both ABRs in a
given virtual link operate. In this use, the area ID is sometimes
termed “transit area ID”. This value must be the same for both
ABRs in the virtual link.
< ip-address >: For an ABR in a given virtual link, this is the
IP address used to create the link on that ABR. (This IP address
matches the IP address of the interface on the opposite end of
the virtual link. Refer to the description of < ip-address > in the
syntax description under “Configuring a Virtual Link” on
page 5-83.)
Use show ip ospf virtual-link < ip-address > to view the current
setting. (Refer to the example on page 5-106.)
Default: 40 seconds; Range: 1 - 65535 seconds.
5-85