View - ADTRAN Support Community
View - ADTRAN Support Community
View - ADTRAN Support Community
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Additional BGP Configuration<br />
(config-bgp-neighbor)#prefix-list [in | out]<br />
Assigns the specified prefix list to this BGP neighbor.<br />
in Specifies that all inbound BGP route updates received from the neighbor are filtered.<br />
out Specifies that all outbound BGP route updates being sent to the neighbor are filtered.<br />
A prefix list can be used to create even more complicated policies when it is applied to a<br />
route map entry rather than a BGP neighbor (as shown above). Refer to Route Map on<br />
page 23 for more information on this option.<br />
Route Map<br />
Route maps allow configuration of more complex policies than prefix lists. In addition to filtering routes<br />
according to IPv4 network address and prefix length, routes can be filtered according to their AS path,<br />
metric value, or BGP community. A BGP community is a group of routes to which a BGP router applies<br />
the same policies. Refer to BGP Communities on page 13 for more information on BGP communities.<br />
Route maps can also be configured to apply various attributes to the routes it filters. A route map applied to<br />
outbound data determines how the router advertises routes to a neighbor. The outbound route map can be<br />
configured to perform such tasks as:<br />
• Define the routes that the router can advertise according to specified attributes or prefixes<br />
• Prepend private AS numbers to specific routes to help balance inbound traffic<br />
• Set an MED on specific routes to help balance inbound traffic<br />
• Request that the neighbor advertise the route to certain communities only<br />
When a route map is applied to inbound data, it determines which of the service provider advertised routes<br />
the local router accepts. The inbound route map can be configured to perform such tasks as:<br />
• Filter external routes according to specified attributes or prefixes<br />
• Apply attributes to filtered routes, including:<br />
– Local preference<br />
– <strong>Community</strong><br />
– MED value<br />
– Prepended AS path<br />
• Delete communities defined for the routes<br />
The route map itself is created first. Matching criteria and attributes are defined within the route map<br />
configuration menu. Once a route map has been established, it can be assigned to a BGP neighbor.<br />
Use the route-map command to create a route map and enter the Route Map Configuration mode.<br />
(config)#route-map <br />
(config)#route-map [deny | permit] <br />
Specifies a name for the route map.<br />
deny Specifies not to process routes matching the specified route map attributes.<br />
permit Processes routes matching the specified route map attributes.<br />
Specifies a sequence number for this route entry. Range is 1 to 4294967295.<br />
61200860L1-29.4E Copyright © 2012 <strong>ADTRAN</strong>, Inc. 23