Setting the Administrative Distance for a Route

The administrative distance is an integer that is associated with each route known to a router. The distance represents how reliable the source of the route is considered to be. A lower value is preferred over a higher value. An administrative distance of 255 indicates no confidence in the source; routes with this distance are not installed in the routing table.

Table 6 lists the default distance for each type of source from which a route can be learned.

Table 6: Default Administrative Distances for Route Sources

If the IP routing table contains several routes to the same prefix—for example, an OSPF route and a RIP route—the route with the lowest administrative distance is used for forwarding.

To set the administrative distance for BGP routes, see JUNOSe BGP and MPLS Configuration Guide.

To set the administrative distance for RIP, IS-IS, and OSPF, use the following distance commands in Router Configuration mode.

distance

• Use to set an administrative distance for RIP or OSPF routes in the range 0–255.
• For RIP routes, the default value is 120.
• For OSPF routes, the default value is 110.
• Example

  host1(config)#router rip

  host1(config-router)#distance 100

• Use the no version to restore the default value.
• See distance

distance ip

• Use to set the administrative distance for IS-IS routes in the range 1–255.
• Example

  host1(config)#router isis

  host1(config-router)#distance 80 ip

• Use the no version to restore the default value of 115.
• See distance ip

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