Configure IPv6 BGP Route Control

Configuration Condition

Before configuring BGP route control, ensure that:

• BGP is enabled.
• IPv6 BGP neighbors are configured and a session is set up successfully.

Configure BGP to Advertise Aggregated Routes

In a large-scale BGP network, to decrease the number of routes that are advertised to neighbors or effectively control BGP routing, you can configure a BGP aggregated route.

Table 13-12 Configure BGP to advertise aggregated routes

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  When configuring BGP to advertise aggregated routes, you can specify the summary-only option so that BGP advertises only aggregated routes. This decreases the number of routes that are advertised.
• You can specify the as-set option to generate aggregation routes with the AS_PATH property.
• You can also apply a route map to the aggregation routes so as to set more abundant properties for the aggregation routes.

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Configure the Administrative Distance of BGP Routes

In the IP route table, each protocol controls the administrative distance of routing. The smaller the administrative distance is, the higher the priority is .BGP affects routing by specifying the administrative distances of specified network segments. The administrative distances of the routes that cover the specified network segments will be modified. Meanwhile, ACL is applied to filter the network segments that are covered by the routes, that is, only the administrative distances of the network segment that are allowed by the ACL can be modified.

The distance bgp command is used to modify the management distances of external, internal, and local BGP routes. The distance command is only used to modify the administrative distances of specified network segments. The distance command has a higher priority than the distance bgp command. The network segments that are covered by the distance command use the administrative distance that is specified by the command, while the network segments that are not covered by the distance command use the administrative distance that is specified by the distance bgp command.

Table 13-13 Configure the administrative distance of a BGP route

Configure Routing Policies in the Outgoing Direction of a BGP Neighbor

BGP route advertising or routing is implemented based on the powerful routing properties. When advertising routes to neighbors, you can apply routing policies to modify route properties or filter some routes. Currently, the routing policies that can be applied in the outgoing direction include:

• distribute-list: Distribution list.
• filter-list: AS_PATH property filtration list.
• prefix-list: IP prefix list.
• route-map: Route map.

Table 13-14 Configure routing policies in the outgoing direction of a BGP neighbor

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  After configuring the routing policy in the outgoing direction of a BGP neighbor, you need to reset the neighbor to validate the settings.
• If you apply a route map in the outgoing direction of a route reflector, this changes only the NEXT-HOP property.
• For how to configure a filtration list, refer to the "Configure AS-PATH" section of the "Routing Policy Tools" chapter.
• In configuring routing policies in the outgoing direction of a BGP neighbor, you can configure multiple policies at the same time. BGP applies routing policies in the sequence of distribute-list, filter-list, prefix-list, and route-map. If a former policy is rejected, the latter policies will not be applied. The routing information can be advertised only after it passes all the configured policies.
• The route map that is applied in the outgoing direction of a BGP route supports match options, including as-path, community, extcommunity, ipv6 address, ip nexthop, and metric, and it supports the set options, including as-path, comm-list, community, extcommunity, ipv6 next-hop, local-preference, metric, origin, and weight.

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