User Manual
UMN:CLI
V8102
665
12.2.6.9
Virtual Link
In OSPF, all areas must be connected to a backbone area. If there is a break in backbone
continuity, or the backbone is purposefully portioned, you can establish a virtual link. The
virtual link must be configured in both routers.
OSPF network regards virtual link routers as Point-to-point router. Therefore, the Hello-
interval, Retransmit-interval, Transmit-delay must be consistent across all routers in an at-
tached network.
User can configure Authentication for security, Authentication key for password, and time
period for Hello-interval, Retransmit-interval, Transmit-delay and Dead-interval to operate
virtual link.
The following items describe 7 configurations for virtual link:
•
Authentication
This is configuration for security of routing information.
message-digest
uses MD5
to encode for authentication,
null
means not using any of authentication.
•
Authentication-key
Configures the authentication which is based on text encoding.
•
Message-digest-key
Configures the authentication which is based on md5 type.
•
Hello-interval
OSPF router sends Hello packet to notify existence of itself. Hello-interval is that
packet transmission interval.
•
Retransmit-interval
When router transmits LSA, it is waiting for approval information come from receiver.
In this time, if there is no answer from receiver for configured time, the router trans-
mits LSA again. Retransmit-interval is configuration of the time interval between
transmission and retransmission
•
Dead-interval
If there is no hello packet for the configured time. The router perceives other router is
stopped working. Dead-interval is configuration of the time interval which perceives
other router is stopped operating.
•
Transmit-delay
When a router transmits LSA, the traffic can be delayed by status of communications.
Transmit-delay is considering of the configuration for LSA transmission time.
Configuration for virtual link can be selected more than 2 options without order. The fol-
lowing is explaining options of command:
•
authentication
[
message-digest
|
null
]
•
authentication-key KEY
•
message-digest-key KEY md5 KEY
•
hello-interval
<1-65535>
•
retransmit-interval
<1-65535>
•
dead-interval
<1-65535>
•
transmit-delay
<1-65535>
