area virtual-link

area virtual-link

Configures or deletes a virtual link entry.

Syntax: [no] 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 password]

area-id

The ID of the area for which these parameters are being set. This is known as the transit area.

router-id

The ID of the router at the other end of the virtual link.

hello-interval seconds

The length of time, in seconds, between Hello packets that the router sends on the interface. Revert back to the default value by omitting the seconds field in the command.

retransmit-interval seconds

The number of seconds between link state advertisement retransmissions for adjacencies belonging to this interface.

transmit-delay seconds

The estimated number of seconds required to transmit a link state update over this interface. Transmit-delay takes into account transmission and propagation delays and must be greater than 0.

dead-interval seconds

The number of seconds not hearing a router's Hello packets before the router's neighbors will declare it down. Revert back to the default value by omitting the seconds field in the command line.

authentication-key key

Used by OSPF authentication to generate and verify the authentication field in the OSPF header. The authentication key can be configured on a per interface basis. It is specified by one to eight decimal digits separated by periods, a one to eight byte hexadecimal string preceded by 0x, or a one to eight character string in double quotes.

message-digest-key keyID

Used by OSPF to determine the password on the receiving end of a link in an area configured for MD5 authentication. The password associated with a key ID replaces the message-digest in the received message. A new message-digest is generated. If the two message-digests match, the packet is accepted by the receiving interface.

md5 password

The MD5 password associated with a key ID used to generate a message-digest at both ends of the link.

Description: Virtual links are used to establish or increase connectivity of the backbone area. The router-ID is the other end of the virtual link. All standard interface parameters defined by the interface clause above may be specified on a virtual link. Each option can be used on its own command line or all options may be included in a single command line.

Use the area area-id virtual-link router-id command to create an OSPF virtual link.

Use the hello-interval seconds keyword and argument to configure the number of seconds between OSPF hello packets.

Use the retransmit-interval seconds keyword and argument to configure the number of seconds between retransmission of LSAs.

Use the transmit-delay seconds keyword and argument to configure the estimated transmission delay due to propagation delay.

Use the dead-interval seconds keyword and argument to configure the number of seconds that elapse without receiving a hello packet before this router declares a neighbor to be down.

Use the authentication-key key keyword and argument to configure simple authentication and password.

Use the message-digest-key keyID md5 password keywords and arguments to configure MD5 authentication, keyID, and the associated MD5 password.

Use the no area virtual-link command to delete the virtual link.

Factory Default: No areas, router ID, authentication or virtual links are pre-configured. Hello-interval: 10 seconds. Dead-interval: 4 times the value of the hello-interval.

Command Mode: Router configuration.

Example 1: In the following example:

The router ospf command enables OSPF and specifies an OSPF process number

The two network area area-id commands enable OSPF on two networks and assigns them area IDs of 0 and 2

The area area-id virtual-link router-id authentication-key key command creates a virtual link between area 0 and in area 2 using simple authentication and key.

The area area-id virtual-link router-id hello-interval seconds dead-interval seconds command configures the hello interval and dead time for the same virtual link:

router(config)#router ospf 13

router(config-router)#network 10.3.9.0 0.0.0.255 area 0

router(config-router)#network 10.1.1.0 0.0.0.255 area 0

router(config-router)#network 10.9.8.0 0.0.0.255 area 2

router(config-router)#area 2 virtual-link 10.9.9.2 authentication-key 5975615

router(config-router)#area 2 virtual-link 10.9.9.2 hello-interval 15 dead-interval 60

Example 2: In the following example:

The router ospf command enables OSPF and specifies an OSPF process number

The two network area area-id commands enable OSPF on two networks and assigns them area IDs of 0 and 2

The area area-id virtual-link router-id message-digest-key keyID md5 password command creates a virtual link with MD5 authentication and sets the MD5 password:

router(config)#router ospf 10

router(config-router)#network 10.3.9.0 0.0.0.255 area 0

router(config-router)#network 10.1.1.0 0.0.0.255 area 0

router(config-router)#network 10.9.8.0 0.0.0.255 area 2

router(config-router)#area 2 virtual-link 10.9.9.2 message-digest-key 17 md5 kaczowka

Related Commands: network area
router ospf

area-id	The ID of the area for which these parameters are being set. This is known as the transit area.
router-id	The ID of the router at the other end of the virtual link.
hello-interval seconds	The length of time, in seconds, between Hello packets that the router sends on the interface. Revert back to the default value by omitting the seconds field in the command.
retransmit-interval seconds	The number of seconds between link state advertisement retransmissions for adjacencies belonging to this interface.
transmit-delay seconds	The estimated number of seconds required to transmit a link state update over this interface. Transmit-delay takes into account transmission and propagation delays and must be greater than 0.
dead-interval seconds	The number of seconds not hearing a router's Hello packets before the router's neighbors will declare it down. Revert back to the default value by omitting the seconds field in the command line.
authentication-key key	Used by OSPF authentication to generate and verify the authentication field in the OSPF header. The authentication key can be configured on a per interface basis. It is specified by one to eight decimal digits separated by periods, a one to eight byte hexadecimal string preceded by 0x, or a one to eight character string in double quotes.
message-digest-key keyID	Used by OSPF to determine the password on the receiving end of a link in an area configured for MD5 authentication. The password associated with a key ID replaces the message-digest in the received message. A new message-digest is generated. If the two message-digests match, the packet is accepted by the receiving interface.
md5 password	The MD5 password associated with a key ID used to generate a message-digest at both ends of the link.

router(config)#router ospf 13 router(config-router)#network 10.3.9.0 0.0.0.255 area 0 router(config-router)#network 10.1.1.0 0.0.0.255 area 0 router(config-router)#network 10.9.8.0 0.0.0.255 area 2 router(config-router)#area 2 virtual-link 10.9.9.2 authentication-key 5975615 router(config-router)#area 2 virtual-link 10.9.9.2 hello-interval 15 dead-interval 60

router(config)#router ospf 10 router(config-router)#network 10.3.9.0 0.0.0.255 area 0 router(config-router)#network 10.1.1.0 0.0.0.255 area 0 router(config-router)#network 10.9.8.0 0.0.0.255 area 2 router(config-router)#area 2 virtual-link 10.9.9.2 message-digest-key 17 md5 kaczowka

   Source File Name: ospf.fm
    HTML File Name: ospf6.html
    Last Updated: 05/10/04 at 16:34:58

area virtual-link

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