API Guide

10.10.10.2. So the routes from 10.10.10.1/24 network is distributed to neighbor 10.10.10.2 since the IP prefix list route10
explicitly permits the routes to be distributed to the neighbor.
To view the BGP configuration, use the show config command in ROUTER BGP mode. To view a prefix list configuration, use
the show ip prefix-list detail or show ip prefix-list summary commands in EXEC Privilege mode.
Filtering BGP Routes Using Route Maps
To filter routes using a route map, use these commands.
1. Create a route map and assign it a name.
CONFIGURATION mode
route-map map-name [permit | deny] [sequence-number]
2. Create multiple route map filters with a match or set action.
CONFIG-ROUTE-MAP mode
{match | set}
For information about configuring route maps, see Access Control Lists (ACLs).
3. Return to CONFIGURATION mode.
CONFIG-ROUTE-MAP mode
exit
4. Enter ROUTER BGP mode.
CONFIGURATION mode
router bgp as-number
5. Filter routes based on the criteria in the configured route map.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | ipv6-address | peer-group-name} route-map map-name {in | out}
Configure the following parameters:
● ip-address or ipv6-address or peer-group-name: enter the neighbor’s IPv4 or IPv6 address or the peer group’s
name.
● map-name: enter the name of a configured route map.
● in: apply the route map to inbound routes.
● out: apply the route map to outbound routes.
DellEMC# configure terminal
DellEMC(conf)# route-map route1 permit
DellEMC(conf-route-map)# set as-path prepend 400
DellEMC(conf-route-map)#exit
DellEMC(conf)# router bgp 400
DellEMC(conf-router_bgp)# neighbor 10.10.10.1 route-map route1 out
DellEMC(conf-router_bgp)#
In the above example, a route-map named route1 is created with a permit clause. Within the route-map, a set clause is
configured to prepend an AS is configured. This configuration adds the configured AS number to the AS-Path for each route.
The configured route-map is applied to the outbound routes of the neighbor 10.10.10.1.
To view the BGP configuration, use the show config command in CONFIGURATION ROUTER BGP mode. To view a route
map configuration, use the show route-map command in EXEC Privilege mode.
Filtering on an AS-Path Attribute
You can use the BGP attribute, AS_PATH, to manipulate routing policies.
The AS_PATH attribute contains a sequence of AS numbers representing the route’s path. As the route traverses an AS, the
ASN is prepended to the route. You can manipulate routes based on their AS_PATH to affect interdomain routing. By identifying
certain ASN in the AS_PATH, you can permit or deny routes based on the number in its AS_PATH.
AS-PATH ACLs use regular expressions to search AS_PATH values. AS-PATH ACLs have an “implicit deny.” This means that
routes that do not meet a deny or match filter are dropped.
Border Gateway Protocol (BGP)
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