WB1 7.32 BGP Aggregation - Unsuppress Map

7.32 BGP Aggregation - Unsuppress Map
• Remove the summarization configured in R2.
• 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.
 
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In this scenario, R3 and R5 perform prefix aggregation. R3 is configured to
unsuppress and advertise one specific prefix - 10.0.1.0/24 to SW1. When AS 54
receives all prefixes, it prefers to reach 10.0.1.0/24 via AS 300, as this is the way
that explicit prefix has travelled to reach AS54.
 
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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
 
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Rack1R3#show ip bgp | include 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#
 
Rack1R5#show ip bgp | include 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
Rack1R5#
 
Now look at the routes that R3 advertises to SW1. Notice that the prefix 10.0.1.0/24 is included, even though it is marked as “suppressed”. That means that the prefix was unsuppressed by the configured feature.

Rack1R3#show ip bgp neighbors 155.1.37.7 advertised-routes | include 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
Rack1R3#

Rack1R6#show ip route | include 10.0
D       155.1.10.0/24 [90/2177792] via 155.1.146.4, 2d22h, FastEthernet0/0.146
     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
B       10.0.0.0/22 [200/0] via 155.1.13.3, 00:19:11
B       10.0.1.0/24 [20/0] via 155.1.67.7, 00:05:13
D       150.1.10.0 [90/2305536] via 155.1.146.4, 2d22h, FastEthernet0/0.146
Rack1R6#