area virtual-link
Use this command to configure a link between two backbone areas that are physically separated through other nonbackbone areas.
Use the no parameter with this command to remove the virtual link.
In OSPFv3, all non-backbone areas must be connected to a backbone area. If the connection to the backbone is lost, the virtual link repairs the connection.You can configure virtual links between any two backbone routers that have an interface to a common non-backbone area. The protocol treats these two routers joined by a virtual link as if they were connected by an unnumbered point-to-point network.
Configure the hello-interval to be the same for all routers attached to a common network. If the hello-interval is short, the router detects topological changes faster, but more routing traffic follows.
The retransmit-interval is the expected round-trip delay between any two routers in a network. Set the value to be greater than the expected round-trip delay to avoid needless retransmissions.
The transmit-delay is the time taken to transmit a link state update packet on the interface. Before transmission, the link state advertisements in the update packet are increased by this amount. Set the transmit-delay to be greater than zero. Also, take into account the transmission and propagation delays for the interface.
Command Syntax
area (A.B.C.D|<0-4294967295>) virtual-link A.B.C.D
area (A.B.C.D|<0-4294967295>) virtual-link A.B.C.D fall-over bfd
area (A.B.C.D|<0-4294967295>) virtual-link A.B.C.D (dead-interval <1-65535>|hello-interval <1-65535>|retransmit-interval <1-1800>|transmit-delay <1-1800>)
area (A.B.C.D|<0-4294967295>) virtual-link A.B.C.D instance-id (<0-31>|<64-95>)
no area (A.B.C.D|<0-4294967295>) virtual-link A.B.C.D fall-over bfd
no area (A.B.C.D|<0-4294967295>) virtual-link A.B.C.D
no area (A.B.C.D|<0-4294967295>) virtual-link A.B.C.D (dead-interval|hello-interval|retransmit-interval|transmit-delay)
no area (A.B.C.D|<0-4294967295>) virtual-link A.B.C.D instance-id
Parameters
A.B.C.D
OSPF Area ID in IP64 address format.
<0-4294967295>
OSPF Area ID as a decimal value.
A.B.C.D
Specify router ID associated with a virtual link neighbor.
dead-interval
The interval in seconds during which no packets are received and after which the router acknowledges a neighboring router as off-line.
<1-65535>
The timer interval.
hello-interval
The interval in seconds the router waits before it sends a hello packet.
<1-65535>
The timer interval.
retransmit-interval
The interval in seconds the router waits before it retransmits a packet.
<1-1800>
The timer interval.
transmit-delay
The interval in seconds the router waits before it transmits a packet.
<1-1800>
The timer interval.
instance-id
The OSPFv3 instance.
<0-31>
Interface instance ID for IPv6 unicast
<64-95>
Interface instance ID for IPv4 unicast.
fall-over bfd
Fall-over Bidirectional Forwarding Detection (BFD).
Default
Default hello interval:10 seconds.
Default dead interval:40 seconds.
Default retransmit interval: 5 seconds.
Default transmit delay: 1 second
Default instance-id: 0
Command Mode
Router mode
Applicability
This command was introduced before OcNOS version 1.3.
Examples
#configure terminal
(config)#router ipv6 ospf
(config-router)#area 1 virtual-link 10.10.11.50 hello 5 dead 10
(config-router)#area 1 virtual-link 10.10.11.50 instance-id 1
(config-router)#area 1 virtual-link 10.10.11.50 fall-over bfd
Last modified date: 08/28/2023