Table of Contents

Syntax Description
Keywords
Examples
Related Commands

OSPF Virtual Link

This section defines configuration parameters for an OSPF Virtual Link. Configuring a virtual link is the only way to allow an area which is not contiguous to the backbone area (area 0) to operate. The virtual link must be configured in both routers which are providing the tunnel to the backbone. These two routers do not need to be physically connected, but they must share a common area called the "transit area."

Syntax Description

RouterID_IPAddress

The Router ID of the virtual neighbor. The Router ID of the virtual neighbor is the largest IP interface address associated with that router. You can request the Router ID of the virtual neighbor by issuing the show ospf rtrid command.

Keywords

After entering the configure command for the section, enter one or more of the following keywords.

LinkActive = {On | Off}	The LinkActive keyword specifies whether an OSPF virtual link will operate. On activates the virtual link. Off deactivates the virtual link.
TransitArea = AreaID	The TransitArea keyword designates the area that is to function as the transit area. The transit area is the area number assigned to the tunnel "between" the two routers of the virtual link. Each router must have at least one interface attached to the transit area. The AreaID can be specified as a number between 0 and 0xFFFFFFFF or as an IP address in dotted-decimal notation.
VirtTransDelay = Number	The VirtTransDelay keyword sets the amount of time added to the age of Link State Update packets before transmission. It is the estimated number of seconds to transmit a packet over the virtual link. The value can be between 1 and 65,535 seconds. The default is 4.
VirtRetrans = Number	The VirtRetrans keyword sets the interval, in seconds, between retransmission of Link State Update packets across the virtual link. The value can be between 2 and 65,535 seconds. The default is 30.
VirtHelloInt = Number	The VirtHelloInt sets the interval, in seconds, that the router sends out "keepalive" packets across the virtual link to let the other end of the link know the router is up. The value must be greater than 10 seconds. The default is 30.
VirtRtrDeadInt= Number	The VirtRtrDeadInt keyword sets the length of time, in seconds, that this router will wait without receiving a "keepalive" packet from the other end of the virtual link before assuming it's down. The value must be at least twice the VirtHelloInterval. The default is 4 times the VirtHelloInterval. Note   The VirtHelloInterval and VirtRtrDeadInterval for each end of the virtual link must match or the virtual link will not function. If you change the settings on one router, you must change them on the other.
VirtAuthKey = String	The VirtAuthKey keyword sets the OSPF packet authentication key for the virtual link. The authentication key must be the same for both ends of the virtual link. The string may be between one and 8 alphanumeric characters. If the string contains spaces or other special characters, it must be enclosed in quotes.

Examples

This example shows a virtual link which uses the default settings.

LinkActive       = On   
TransitArea      = 2   
VirtRetrans      = 30   
VirtTransDelay   = 4    
VirtHelloInt     = 30   
VirtRtrDeadInt   = 120  
VirtAuthKey      = "Zooey" 
 

Related Commands

Command	Description
configure IP	Configures IP parameters for an interface
configure IP Route Redistribution	Configures how the concentrator redistrubutes routes from one dynamic IP routing protocol into another.
configure OSPF Area	Configures OSPF area parameters
show ospf	Shows OSPF configuration and statistics

Posted: Wed Sep 27 10:47:09 PDT 2000
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