Concept Guide

reducing the convergence time. You can congure BGP to congure and advertise aggregated routes. At least one specic route of the
aggregate must be in the routing table for the congured aggregate to become active.
To aggregate routes, use the following command.
AS_SET includes AS_PATH and community information from the routes included in the aggregated route.
• Assign the IP address and mask of the prex to be aggregated.
CONFIG-ROUTER-BGP mode
aggregate-address ip-address mask [advertise-map map-name] [as-set] [attribute-map map-name]
[summary-only] [suppress-map map-name]
– as-set- Specify that the advertised path of this route is an AS_SET.
– summary-only-Create aggregate route and suppress advertisements of specic routes to all neighbors.
– suppress-map map-name-Create aggregate route by suppressing the advertisements of specic routes.
– advertise-map map-name-Create aggregate route by advertising specic routes.
Conguring BGP aggregate routes
To create an aggregate route entry in the BGP routing table, use the following commands.
The aggregate route is advertised from the autonomous system.
• Enter the router conguration mode and the AS number for the specic BGP routing process.
CONFIG mode
router bgp as-number
• Create an aggregate entry in the BGP routing table.
CONFIG-ROUTER-BGP mode
aggregate—address address-mask
Use the aggregate-address command without any keywords to create an aggregate entry if any specic BGP routes are available
in the specied range.
Example of conguring aggregate routes using BGP
DellEMC# configure terminal
DellEMC(conf)# router bgp 100
DellEMC(conf-router_bgp)# aggregate-address 10.1.1.0/24
DellEMC(conf-router_bgp)# exit
DellEMC(conf)#
Following is the sample output of show ip bgp command.
DellEMC# show ip bgp
BGP local RIB : Routes to be Added 0, Replaced 0, Withdrawn 0
BGP local router ID is 30.30.30.30
Status codes: s suppressed, S stale, d dampened, h history, * valid, > best
Path source: I - internal, a - aggregate, c - confed-external, r - redistributed
n - network, D - denied, S - stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>r 3.3.3.0/24 0.0.0.0 0 32768 ?
s>r 10.1.1.0/30 0.0.0.0 0 32768 ?
*>r 30.30.30.30/32 0.0.0.0 0 32768 ?
*>a 10.1.1.0/24 0.0.0.0 32768 ?
Border Gateway Protocol (BGP)
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