Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 - Manual (Page 327)

Brocade ICX 6650 Layer 3 Routing Configuration Guide 309
53-1002603-01
Optional BGP4 configuration tasks
The route-map map-name parameter specifies the name of the route map you want to use to set or
change BGP4 attributes for the network you are advertising. The route map must already be
configured.
For information about the other parameters, refer to “Defining route maps” on page 342.
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 autonomous systems.
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. Refer to “Defining route maps” on
page 342. Refer to “How BGP4 selects a path for a route” on page 283 for information about the
BGP4 algorithm.
To change the default local preference to 200, enter the following command.
Brocade(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 through 4294967295.
Using the IP default route as a valid next hop for
a BGP4 route
By default, the Layer 3 switch does not use a default route to resolve a BGP4 next-hop route. If the
IP route lookup for the BGP4 next hop does not result in a valid IGP route (including static or direct
routes), the BGP4 next hop is considered to be unreachable and the BGP4 route is not used.
In some cases, such as when the Layer 3 switch is acting as an edge router, you might want to allow
the device to use the default route as a valid next hop. To do so, enter the following command at
the BGP4 configuration level of the CLI.
Brocade(config-bgp-router)#next-hop-enable-default
Syntax: [no] next-hop-enable-default