Siemens S223, S323 user manual Administrative Distance, Originating Default Information

User Manual	UMN:CLI
SURPASS hiD 6615 S223/S323 R1.5

10.3.7Administrative Distance

Administrative distance is a measure of the trustworthiness of the source of the routing in- formation.

In large scaled network, Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (be- lievable) with the help of an administrative distance value.

Remember that administrative distance has only local significance, and is not advertised in routing updates. Most routing protocols have metric structures and algorithms that are not compatible with other protocols. In a network with multiple routing protocols, the ex- change of route information and the capability to select the best path across the multiple protocols are critical. Administrator should set the distance value based on whole routing networks.

To configure the administrative distance value, use the following command.

Command	Mode	Description
		Sets the administrative distance value for routes.
distance <1-255> [A.B.C.D/M		1-255: distance value
[ACCESS-LIST]]	Router	A.B.C.D/M: IP source prefix
		ACCESS-LIST: access list name
no distance [<1-255>] [A.B.C.D/M		Deletes the administrative distance value.
[ACCESS-LIST]]

10.3.8Originating Default Information

You can set an autonomous system boundary router to generate and transmit a default route into an RIP routing domain. If you specifically set to generate a default routes into an RIP network, this router becomes an autonomous system (AS) boundary router. How- ever, an AS boundary router does not generate a default route automatically into the RIP network.

To generate a default route into RIP by the AS boundary router, use the following com- mand on Router Configuration mode.

Command	Mode	Description
default-information originate		Generates a default route into RIP by the AS boundary
	Router	router.
no default-information originate		Disables a default route feature.

10.3.9Routing Information Filtering

You can limit the routing protocol information by performing the following tasks.

•Block the transmission of routing information to a particular interface. This is to prevent other systems on an interface from learning about routes dynamically.

•Provides a local mechanism for increasing the value of routing metrics.

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