LAB: BGP - Aggregation summary unSuppress Map

- Using the summary-only feature, configure R3 and R5 to originate an aggregate route for these networks that does not overlap any address space.
- Using the unsuppress-map feature configure the network in such a way that traffic from AS 100 and 54 going to the prefix 10.0.1.0/24 always transits AS 300 unless the link between R3 and SW1 is down.
 - Traffic from these ASes going to other subnets of the aggregate should use the direct path through the network.

This is often used to do a load balancing for the ingress traffic. To implement this technique, you may use the unsuppress-map BGP feature. This feature could be only configured on the router that performs prefix aggregation using the command aggregate-address ... summary-only. The feature uses a special route-map that matches and permits the prefixes need to be unsuppressed. The feature is applied only on per-neighbor basis.

configuration:

R2:
router bgp 200
no aggregate-address 10.0.0.0 255.255.252.0
R3:
ip prefix-list NET_1 permit 10.0.1.0/24
!
route-map UNSUPPRESS_MAP permit 10
match ip address prefix-list NET_1
!
router bgp 200
aggregate-address 10.0.0.0 255.255.252.0 summary-only
neighbor 155.1.37.7 unsuppress-map UNSUPPRESS_MAP
R5:
router bgp 200
aggregate-address 10.0.0.0 255.255.252.0 summary-only

verification:

Rack1R3#show ip bgp | inc 10.0
*Mar  1 00:25:38.679: %SYS-5-CONFIG_I: Configured from console by console
Rack1R3#show ip bgp | inc 10.0
s>i10.0.0.0/24      155.1.23.2               0    100      0 i
* i10.0.0.0/22      155.1.0.5                0    100      0 i
s>i10.0.1.0/24      155.1.23.2               0    100      0 i
s>i10.0.2.0/24      155.1.23.2               0    100      0 i
s>i10.0.3.0/24      155.1.23.2               0    100      0 i

Rack1R3#show ip bgp neighbors 155.1.37.7 advertised-routes | inc 10.0
*> 10.0.0.0/22      0.0.0.0                            32768 i
s>i10.0.1.0/24      155.1.23.2               0    100      0 i

Rack1R5#show ip bgp | inc 10.0
s>i10.0.0.0/24      155.1.0.2                0    100      0 i
*> 10.0.0.0/22      0.0.0.0                            32768 i
s>i10.0.1.0/24      155.1.0.2                0    100      0 i
s>i10.0.2.0/24      155.1.0.2                0    100      0 i
s>i10.0.3.0/24      155.1.0.2                0    100      0 i

Rack1R6#show ip route 10.0.1.0
Routing entry for 10.0.1.0/24
  Known via "bgp 100", distance 20, metric 0
  Tag 300, type external
  Last update from 155.1.67.7 00:00:39 ago
  Routing Descriptor Blocks:
  * 155.1.67.7, from 155.1.67.7, 00:00:39 ago
      Route metric is 0, traffic share count is 1
      AS Hops 2
      Route tag 300


Rack1R6#show ip route 10.0.2.0
Routing entry for 10.0.0.0/22
  Known via "bgp 100", distance 200, metric 0
  Tag 200, type internal
  Last update from 155.1.13.3 00:01:14 ago
  Routing Descriptor Blocks:
  * 155.1.13.3, from 155.1.146.1, 00:01:14 ago
      Route metric is 0, traffic share count is 1
      AS Hops 1
      Route tag 200