Changing The Default Local Preference - Foundry Networks Switch and Router Installation And Configuration Manual

Foundry Switch and Router Installation and Configuration Guide
USING THE WEB MANAGEMENT INTERFACE
You cannot add a route map to a BGP4 network definition using the Web management interface.

Changing the Default Local Preference

When the router uses the BGP4 algorithm to select a route to send to the IP route table, one of the parameters the
algorithm uses is the local preference. Local preference is an attribute that indicates a degree of preference for a
route relative to other routes. BGP4 neighbors can send the local preference value as an attribute of a route in an
UPDATE message.
Local preference applies only to routes within the local AS. BGP4 routers can exchange local preference
information with neighbors who also are in the local AS, but BGP4 routers do not exchange local preference
information with neighbors in remote ASs.
The default local preference is 100. For routes learned from EBGP neighbors, the default local preference is
assigned to learned routes. For routes learned from IBGP neighbors, the local preference value is not changed
for the route.
When the BGP4 algorithm compares routes on the basis of local preferences, the route with the higher local
preference is chosen.
NOTE: To set the local preference for individual routes, use route maps. See "Defining Route Maps" on
page 19-63. See "How BGP4 Selects a Path for a Route" on page 19-3 for information about the BGP4 algorithm.
To change the default local preference used by the router, use either of the following methods.
USING THE CLI
To change the default local preference to 200, enter the following command:
BigIron(config-bgp-router)# default-local-preference 200
Syntax: default-local-preference <num>
The <num> parameter indicates the preference and can be a value from 0 – 4294967295.
USING THE WEB MANAGEMENT INTERFACE
1. Log on to the device using a valid user name and password for read-write access. The System configuration
panel is displayed.
2. Click on the plus sign next to Configure in the tree view to expand the list of configuration options.
3. Click on the plus sign next to BGP in the tree view to expand the list of BGP option links.
4. Click on the General link to display the BGP configuration panel, shown in Figure 19.2 on page 19-8.
5. Change the number in the Default Local Preference field. You can enter a number from 0 – 4294967295.
6. Click the Apply button to apply the changes 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.
Advertising the Default Information Originate
By default, the router does not originate and advertise a default route using BGP4. A BGP4 default route is the IP
address 0.0.0.0 and the route prefix 0 or network mask 0.0.0.0. For example, 0.0.0.0/0 is a default route. You can
enable the router to advertise a default BGP4 route using either of the following methods.
NOTE: The Foundry Layer 3 Switch checks for the existence of an IGP route for 0.0.0.0/0 in the IP route table
before creating a local BGP route for 0.0.0.0/0.
USING THE CLI
To enable the router to originate and advertise a default BGP4 route, enter the following command:
19 - 32 December 2000