In this post I will show how to configure a suppress-map. For the purpose of this post I used the diagram below, it is the same diagram as I used in the previous post about BGP route-aggregation. In the previous post I showed how to configure this BGP aggregation and what the difference is between the aggregation with and without the “summary-only” option. For the purpose of this post I will start of the same way I started of in the previous post with configuring router R2 to aggregate the 22.22.22.0/29 and 44.44.44.0/29 without the “summary-only” option.
As explained in the previous post router R1 will now see from router R2 all the prefixes specified as /32 routes and also the networks as /29 networks like below :
R1 :
R1#sh ip bgp
BGP table version is 19, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 2.2.2.2/32 10.10.12.2 0 0 65002 i
*> 4.4.4.4/32 10.10.14.4 0 0 65004 i
* 5.5.5.5/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
*> 22.22.22.0/29 10.10.12.2 0 0 65002 i
* 22.22.22.1/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 22.22.22.2/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 22.22.22.3/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 22.22.22.4/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 22.22.22.5/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 22.22.22.6/32 10.10.12.2 0 65002 65005 i
Network Next Hop Metric LocPrf Weight Path
*> 10.10.14.4 0 65004 65005 i
*> 44.44.44.0/29 10.10.12.2 0 0 65002 i
* 44.44.44.1/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.2/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.3/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.4/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.5/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.6/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
Say we would want router R2 to advertise the aggregate /29 and also the 22.22.22.1, 22.22.22.2, 22.22.22.3 and 22.22.22.6 but not the network 22.22.22.4 and the 22.22.22.5 networks. This can be done with a suppress-map, with a suppress-map you can prevent certain networks from being advertised. Below an example of a suppress-map configured on router R2, with this suppress-map all networks except the 22.22.22.4 and the 22.22.22.5 will be advertised by router R2 to router R1.
R2 :
router bgp 65002
no synchronization
bgp router-id 2.2.2.2
bgp log-neighbor-changes
network 2.2.2.2 mask 255.255.255.255
aggregate-address 22.22.22.0 255.255.255.248 suppress-map SUPMAP
aggregate-address 44.44.44.0 255.255.255.248
neighbor 10.10.12.1 remote-as 65001
neighbor 10.10.12.1 send-community
neighbor 10.10.25.5 remote-as 65005
neighbor 10.10.25.5 send-community
no auto-summary
!
ip http server
ip classless
!
!
ip bgp-community new-format
!
!
ip prefix-list SUPMAP seq 5 permit 22.22.22.4/32
ip prefix-list SUPMAP seq 10 permit 22.22.22.5/32
!
route-map SUPMAP permit 10
match ip address prefix-list SUPMAP
The “sh ip bgp” output of router R1 :
R1 :
R1#sh ip bgp
BGP table version is 70, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 2.2.2.2/32 10.10.12.2 0 0 65002 i
*> 4.4.4.4/32 10.10.14.4 0 0 65004 i
* 5.5.5.5/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
*> 22.22.22.0/29 10.10.12.2 0 0 65002 i
* 22.22.22.1/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 22.22.22.2/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 22.22.22.3/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
*> 22.22.22.4/32 10.10.14.4 0 65004 65005 i
*> 22.22.22.5/32 10.10.14.4 0 65004 65005 i
* 22.22.22.6/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
*> 44.44.44.0/29 10.10.12.2 0 0 65002 i
Network Next Hop Metric LocPrf Weight Path
* 44.44.44.1/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.2/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.3/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.4/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.5/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
* 44.44.44.6/32 10.10.12.2 0 65002 65005 i
*> 10.10.14.4 0 65004 65005 i
As you can see router R1 learns routes 22.22.22.4 and 22.22.22.5 only from router R4 while router R2 is still advertising the /29 and the other /32 prefixes to router R1
