Siemens S223 - Manual (Page 367)

User Manual UMN:CLI
SURPASS hiD 6615 S223/S323 R1.5
A50010-Y3-C150-2-7619 367
10.3.7 Administrative 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
distance <1-255> [A.B.C.D/M
[ACCESS-LIST]]
Sets the administrative distance value for routes.
1-255: distance value
A.B.C.D/M: IP source prefix
ACCESS-LIST: access list name
no distance [<1-255>] [A.B.C.D/M
[ACCESS-LIST]]
Router
Deletes the administrative distance value.
10.3.8 Originating 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.
no default-information originate
Router
Disables a default route feature.
10.3.9 Routing 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.