Add OSPF Virtual Link (ADDOSPFLNK)

The Add OSPF Virtual Link (ADDOSPFLNK) command configures a virtual link between two area border routers. To maintain backbone connectivity you must have all of your backbone routers interconnected either by permanent or virtual links. Virtual links are considered to be separate router interfaces connecting to the backbone area. Therefore, you are asked to specify many of the interface parameters when configuring a virtual link.

Virtual links can be configured between any two backbone routers that have an interface to a common non-backbone, non-stub area. Virtual links are used to maintain backbone connectivity and must be configured at both endpoints.

IPv4 and IPv6 OSPF virtual links can be added. The Neighbor router (LNKTMSARA) parameter value will determine whether the virtual link is an IPv4 or IPv6 OSPF virtual link.

Restrictions:

Parameters

Keyword Description Choices Notes
IPVERSION IP version *IPV4, *IPV6 Required, Positional 1
NGHRTR Neighbor router Character value Required, Positional 2
LNKTMSARA Link transmission area Character value Required, Positional 3
RETMSITV Retransmission interval 1-65535, 10 Optional
TMSDLY Transmission delay 1-65535, 5 Optional
ITVHELLO Interval for hello 1-255, 30 Optional
DBEXCHTIMO Database exchange timeout 2-65535, 180 Optional
INACTTIMO Inactive router timeout 2-65535, 40 Optional
AUTHTYPE Authentication type *BACKBONE, *NONE, *MD5, *PASSWORD Optional
AUTHVAL Authentication values Element list Optional
Element 1: Authentication key identifier 1-255
Element 2: Authentication key Character value

IP version (IPVERSION)

Specifies the IP version (IPv4 or IPv6) of the Virtual Link.

This is a required parameter.

*IPV4
This Virtual Link is part of an OSPF IPv4 routing domain.
*IPV6
This Virtual Link is part of an OSPF IPv6 routing domain.

Neighbor router (NGHRTR)

Specifies the router identifier of the neighbor (other endpoint).

This is a required parameter.

character-value
Specify the internet address of the router in the form a.a.a.a where a is a decimal number between 1 and 255.

Link transmission area (LNKTMSARA)

Specifies a non-backbone, non-stub area through which the virtual link is configured. Virtual links can be configured between any two area border routers that have an interface to a common non-backbone and non-stub area. Virtual links must be configured in each of the link's two endpoints.

The IP version of the area must be the same as the virtual link.

This is a required parameter.

character-value
Specify the internet address of the area in the form a.a.a.a where a is a decimal number between 1 and 255.

Retransmission interval (RETMSITV)

Specifies the frequency (in seconds) of retransmitting link-state update packets, link-state request packets, and database description packets.

Note: If this parameter is set too low, needless retransmissions will occur that could affect performance and interfere with neighbor adjacency establishment. It should be set to a higher value for a slower machine.

10
Retransmit packets every 10 seconds.
1-65535
Specify the number of seconds to use for the retransmission interval value.

Transmission delay (TMSDLY)

Specifies the estimated number of seconds that it takes to transmit link-state information over the virtual link. Each link-state advertisement has a finite lifetime of 1 hour. As each link-state advertisement is sent out from this virtual link, it will be aged by this configured transmission delay.

5
This virtual link is on a low-latency network.
1-65535
Specify the number of seconds to use for the transmission delay value.

Interval for hello (ITVHELLO)

Specifies the number of seconds between OSPF hello packets being sent out from this virtual link. The interval for hello should be set higher than the same value used on the intervening OSPF interfaces.

30
Send hello packets every 30 seconds.
1-65535
Specify the number of seconds to use for the hello interval value.

Database exchange timeout (DBEXCHTIMO)

Specifies the length of time that the database exchange process cannot exceed. If the interval elapses, the procedure will be restarted. This value must be larger than the interval for hello.

180
Database exchanges should be completed within 180 seconds.
2-65535
Specify the number of seconds to use for the database exchange timeout value.

Inactive router timeout (INACTTIMO)

Specifies the interval, in seconds, after not having received an OSPF hello, that the neighbor is declared to be down. This value must be larger than the interval for hello. The inactive router timeout should be set higher than the same value used on the intervening OSPF interfaces.

40
The router will be considered down after not having received hello packets in 40 seconds.
2-65535
Specify the number of seconds to use for the inactive router timeout value.

Authentication type (AUTHTYPE)

Specifies the security scheme to be used over the virtual link. This parameter is ignored for OSPF IPv6 virtual links.

*BACKBONE
Use the security schema defined in the OSPF backbone area.
*NONE
No authentication is needed to pass OSPF packets.
*MD5
MD5 cryptographic authentication is used.
*PASSWORD
Simple password authentication is used.

Authentication values (AUTHVAL)

Specifies the combination of parameters needed for cryptographic authentication.

Element 1: Authentication key identifier

0-255
Specify the constant value to use as the key identifier. This value is only meaningful when the authentication type *MD5 is specified and is used with other routers that require identification of an authentication type.

Element 2: Authentication key

character-value
Specify the authentication key for this virtual link. This value must be the same in all routers that are attached to a common network. This value depends on the authentication type used for this interface. This parameter is ignored for OSPF IPv6.

For *NONE authentication type, this parameter element is not required and is ignored if specified.

For authentication type *PASSWORD, this parameter element must specify a password for OSPF routers that are attached to this subnet. Valid values are any character string up to 8 characters in length coded within single quotation marks, or any hexadecimal string up to 8 bytes (16 hexadecimal characters) long beginning with X followed by the hexadecimal value enclosed in single quotation marks.

For authentication type *MD5, this parameter must specify the 16-byte MD5 authentication key for OSPF routers attached to this subnet. The standard method is with a 16-byte hexadecimal string beginning with X followed by the hexadecimal value enclosed in single quotation marks.

Examples

Example 1:Adding an OSPF IPv4 Virtual Link 

ADDOSPFLNK  IPVERSION(*IPV4)  NGHRTR('2.2.2.2')
            LNKTMSARA('3.3.3.3')

This command adds a virtual link for neighbor router 2.2.2.2 with a link transmission area identifier of 3.3.3.3. To add a virtual link for IPv4, you need the router identifier over which the link will be established and the area identifier of the link transmission area. The system must be an area border router. The link transmission area must have been configured for IPv4 previously.

Example 2:Adding an OSPF IPv6 Virtual Link 

ADDOSPFLNK  IPVERSION(*IPV6)  NGHRTR('62.62.62.62')
            LNKTMSARA('63.63.63.63')

This command adds a virtual link for neighbor router 62.62.62.62 with a link transmission area identifier of 63.63.63.63. To add a virtual link for IPv6, you need the router identifier over which the link will be established and the area identifier of the link transmission area. The system must be an area border router. The link transmission area must have been configured for IPv6 previously.

Error messages

*ESCAPE Messages

TCP8050
*IOSYSCFG authority required to use &1.
TCP6531
OSPF virtual link &1 has not added from configuration file. Fails with reason code &2.
TCP9999
Internal system error in program &1.