Configure Aggregate Routes

Configure aggregate routes so that the router advertises a single route (aggregate route) that represents all destinations. Aggregate routes also reduce the size of routing tables.

Before you begin

Disable BGP before you enable aggregation.
You need the appropriate aggregate address and mask.
If required, policies exist.
You configure BGP on a VRF instance the same way you configure the GlobalRouter, except that you must use VRF Router Configuration mode and the prefix ip bgp. The VRF must have an RP Trigger of BGP.

Note

Route refresh is not currently supported on non-default VRFs.

Procedure

Enter BGP Router Configuration mode:

enable

configure terminal

router bgp
Enable BGP aggregation:

bgp aggregation enable
Add an aggregate route to the routing table:

aggregate-address WORD<1–256> {advertise-map WORD<0–1536>] [as-set] [attribute-map WORD<0–1536>] [summary-only] [suppress-map WORD<0–1536>]
Exit to Global Configuration mode:

exit
Enable BGP:

router bgp [<0-65535>] [enable]

Example

Add an aggregate route to the routing table:

Switch(router-bgp)# aggregate-address 2001:DB8::/32 advertise-map map1 attribute-map map2

Enable BGP:

Switch(router-bgp)# router bgp 4 enable

Variable Definitions

The following table defines parameters for the aggregate-address command.


Variable	Value
advertise-map WORD<0-1536>	Specifies the route map name for route advertisements.
as-set	Enables autonomous system information. The default value is disable.
attribute-map WORD<0-1536>	Specifies the route map name.
WORD <1–256>	Specifies an IP address and its length in the appropriate form. The value must be entered in the format a.b.c.d/len or ipv6addr/len.
summary-only	Enables the summarization of routes not included in routing updates. This variable creates the aggregate route and suppresses advertisements of more specific routes to all neighbors. The default value is disable.
suppress-map WORD<0-1536>	Specifies the route map name for the suppressed route list.

The following table defines parameters for the router bgp command.


Variable	Value
`<0-65535>`	Specifies the AS number. You cannot enable BGP until you change the local AS to a value other than 0.
enable	Enables BGP on the router.