Changing The Default Local Preference - Brocade Communications Systems FastIron SX 800 Configuration Manual

NOTE
The exact route must exist in the IP route table before the device can create a local BGP4 route.
To configure the device to advertise network 10.157.22.0/24, enter the following command.
device(config-bgp-router)# network 10.157.22.0 255.255.255.0
Syntax: [no] network ip-addr ip-mask [route-map map-name] | [weight num] | [backdoor]
The ip-addr is the network number and the ip-mask specifies the network mask.
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. If it is not, the default action is to deny redistribution.
The weight num parameter specifies a weight to be added to routes to this network.
The backdoor parameter changes the administrative distance of the route to this network from the EBGP administrative distance (20 by
default) to the Local BGP4 weight (200 by default), tagging the route as a backdoor route. Use this parameter when you want the device
to prefer IGP routes such as RIP or OSPF routes over the EBGP route for the network.
Specifying a route map when configuring BGP4 network advertising
You can specify a route map when you configure a BGP4 network to be advertised. The device uses the route map to set or change
BGP4 attributes when creating a local BGP4 route.
NOTE
You must configure the route map before you can specify the route map name in a BGP4 network configuration; otherwise, the
route is not imported into BGP4.
To configure a route map, and use it to set or change route attributes for a network you define for BGP4 to advertise, enter commands
such as the following.
device(config)# route-map set_net permit 1
device(config-routemap set_net)# set community no-export
device(config-routemap set_net)# exit
device(config)# router bgp
device(config-bgp)# network 10.100.1.0/24 route-map set_net
The first two commands in this example create a route map named "set_net" that sets the community attribute for routes that use the
route map to "NO_EXPORT". The next two commands change the CLI to the BGP4 configuration level. The last command configures a
network for advertising from BGP4, and associates the "set_net" route map with the network. When BGP4 originates the
10.100.1.0/24 network, BGP4 also sets the community attribute for the network to "NO_EXPORT".

Changing the default local preference

When the device 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 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 devices can exchange local preference information with neighbors who
also are in the local AS, but BGP4 devices 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.
FastIron Ethernet Switch Layer 3 Routing
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Optional BGP4 configuration tasks
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