Reference Guide

Open Shortest Path First (OSPFv2 and OSPFv3) | 683
Configure virtual links
Areas within OSPF must be connected to the backbone area (Area ID 0.0.0.0). If an OSPF area does not
have a direct connection to the backbone, at least one virtual link is required. Virtual links must be
configured on an ABR connected to the backbone.
• hello-interval: help packet
• retransmit-interval: LSA retransmit interval
• transmit-delay: LSA transmission delay
• dead-interval: dead router detection time
• authentication-key: authentication key
• message-digest-key: MD5 authentication key
Use the following command in CONFIGURATION ROUTER OSPF mode to configure virtual links.
Use the
show ip ospf process-id virtual-links command in the EXEC mode to view the virtual link.
FTOS#show ip ospf 1 virtual-links
Virtual Link to router 192.168.253.5 is up
Run as demand circuit
Transit area 0.0.0.1, via interface GigabitEthernet 13/16, Cost of using 2
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:02
FTOS#
Command Syntax Command Mode Usage
area area-id virtual-link router-id
[
hello-interval seconds |
retransmit-interval seconds |
transmit-delay seconds |
dead-interval seconds |
authentication-key key |
message-digest-key keyid md5 key]
CONFIG-ROUTER-OSPF-id Configure the optional parameters of a virtual link:
• Area ID: assigned earlier (0-65535 or
A.B.C.D)
• Router ID: IP address associated with the
virtual link neighbor
• Hello Interval Seconds: 1-8192 (default 10)
• Retransmit Interval Seconds: 1-3600 (default
5)
• Transmit Delay Seconds: 1-3600 (default 1)
• Dead Interval Seconds: 1-8192 (default 40)
• Authentication Key: 8 characters
• Message Digest Key: 1-255
• MD5 Key: 16 characters
Only the Area ID and Router ID require configuration to create a virtual link. If no
other parameter is entered, the defaults are used.
Use EITHER the Authentication Key or the Message Digest (MD5) key.