Foundry Networks Switch and Router User Manual

Foundry Switch and Router Installation and Configuration Guide
17 - 36 December 2000
6. Click the Apply button to save the change to the device’s running-config file.
7. Select the Save
link at the bottom of the dialog. Select Yes when prompted to save the configuration change
to the startup-config file on the device’s flash memory.
Modify Administrative Distance
Foundry Layer 3 Switchs can learn about networks from various protocols, including Border Gateway Protocol
version 4 (BGP4), RIP, and OSPF. Consequently, the routes to a network may differ depending on the protocol
from which the routes were learned. The default administrative distance for OSPF routes is 110. See “Changing
Administrative Distances” on page 19-33 for a list of the default distances for all route sources.
The router selects one route over another based on the source of the route information. To do so, the router can
use the administrative distances assigned to the sources. You can bias the Layer 3 Switch’s decision by changing
the default administrative distance for RIP routes.
Configuring Administrative Distance Based on Route Type
You can configure a unique administrative distance for each type of OSPF route. For example, you can use this
feature to prefer a static route over an OSPF inter-area route but you also want to prefer OSPF intra-area routes to
static routes.
The distance you specify influences the choice of routes when the Layer 3 Switch has multiple routes for the same
network from different protocols. The Layer 3 Switch prefers the route with the lower administrative distance.
You can specify unique default administrative distances for the following route types:
• Intra-area routes
• Inter-area routes
• External routes
The default for all these OSPF route types is 110.
NOTE: This feature does not influence the choice of routes within OSPF. For example, an OSPF intra-area route
is always preferred over an OSPF inter-area route, even if the intra-area route’s distance is greater than the inter-
area route’s distance.
To configure administrative distances for OSPF route types, use the following CLI method.
USING THE CLI
To change the default administrative distances for inter-area routes, intra-area routes, and external routes, enter
the following command:
BigIron(config-ospf-router)# distance external 100
BigIron(config-ospf-router)# distance inter-area 90
BigIron(config-ospf-router)# distance intra-area 80
Syntax: distance external | inter-area | intra-area <distance>
The external | inter-area | intra-area parameter specifies the route type for which you are changing the default
administrative distance.
The <distance> parameter specifies the new distance for the specified route type. Unless you change the
distance for one of the route types using commands such as those shown above, the default is 110.
To reset the administrative distance to its system default (110), enter a command such as the following:
BigIron(config-ospf-router)# no distance external 100
Configure OSPF Group Link State Advertisement (LSA) Pacing
The Layer 3 Switch paces LSA refreshes by delaying the refreshes for a specified time interval instead of
performing a refresh each time an individual LSA’s refresh timer expires. The accumulated LSAs constitute a
group, which the Layer 3 Switch refreshes and sends out together in one or more packets.

Foundry Networks Switch and Router Specifications

General

Brand	Foundry Networks
Model	Switch and Router
Category	Switch
Language	English