Netgear XCM8806 Chassis User Manual - Page 711

NETGEAR 8800 User Manual When BGP inactive route advertising is enabled, inactive BGP routes are considered for BGP route aggregation. When this feature is disabled, inactive BGP routes are ignored while aggregating routes. Default Route Origination and Advertisement The default route origination and advertisement feature allows you to originate and advertise a default route to a BGP neighbor (or to all neighbors in a peer group) even though no default route exists in the local IP routing table. It also allows you to associate policy rules to conditionally advertise a default route to BGP neighbors. When default route origination becomes active, the default route is advertised to the specified BGP neighbors, overriding any previously sent default route. If a default route is added to the local IP routing table while default route origination is active, the default route defined by this feature takes precedence over the new regular default route. If default route origination becomes inactive, and a regular default route exists, the regular default route is advertised to BGP neighbors. The following sections provide additional information on this feature: • Managing Policies for Default Route Origination on page 711 • Enabling and Disabling Route Origination on page 712 • Example: Default Route Origination on page 712 Managing Policies for Default Route Origination When you use a policy with default route origination, the default route is originated only if the local BGP RIB contains a route that matches the policy match conditions. You can use the following match conditions: • NLRI • AS-path • Community • Origin You can also use the following policy actions in the policy to set the route attributes: • AS-path • Community • Origin After a policy is configured for default route origination, BGP must periodically scan the local BGP RIB to make sure that the policy rules evaluate to true for at least one route in local BGP RIB. If the rules evaluate to true, default origination remains active. If the rules evaluate to false, then default origination becomes inactive and the default routes must be withdrawn. For more information on policy match conditions, actions, and configuration, see Chapter 14, Routing Policies. Chapter 26. BGP | 711