Chapter 29
| IP Routing Commands
Border Gateway Protocol (BGPv4)
– 965 –
neighbor prefix-list This command configures prefix restrictions applied in inbound/outbound route
updates to/from specified neighbors. Use the no form to remove the neighbor
binding for a prefix list.
Syntax
neighbor {ip-address | group-name} prefix-list list-name {in | out}
no neighbor {ip-address | group-name} prefix-list {in | out}
ip-address – IP address of a neighbor.
group-name – A BGP peer group containing a list of neighboring routers
configured with the neighbor peer-group command.
list-name – Name of a prefix-list. The prefix list can be used to filter the
networks to import or export. (Range: 1-80 characters)
in – Filter inbound routing updates.
out – Filter outbound routing updates.
Command Mode
Router Configuration
Default Setting
No prefix list restrictions are configured.
Command Usage
â—† First, configure a prefix list with the ip prefix-list command, and then use this
command to specify the neighbors to which it applies, and whether it applies
to inbound or outbound messages.
â—† Filtering routes based on a prefix list searches for entries matching the router
specified by this command. If a match is found and the entry is configured to
permit the route, the route will be imported or exported as defined by this
command. An empty prefix list permits all prefixes. If a prefix does not match
any entries in a list, the route is denied. When multiple entries in the list match a
prefix, the entry with the smallest sequence number is used.
â—† The search starts at the top of the prefix list. Once an entry matches, the router
stops searching. To reduce the load on system resources, the most commonly
used entries should be placed at the top of the list.
Example
Console(config)#ip prefix-list RD permit 100.1.0.0 255.255.0.0 ge 17 le 18
Console(config)#router bgp 200
Console(config-router)#redistribute static
Console(config-router)#neighbor 10.1.1.66 prefix-list RD out
Console(config-router)#
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