The last part of the tutorial shows how to manipulate the AS-SET attribute of the aggregate. In a first step the "as-set" option is added to the aggreagte command. The effect is visable on the routers R3 and R4 without resetting the BGP sessions.
R3#sh ip bgp
BGP table version is 90, local router ID is 172.17.0.3
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
*> 10.10.0.0/16 192.168.100.5 0 0 100 i
*> 10.10.10.0/24 192.168.100.5 0 100 80 1000 2000 3000 i
*> 10.10.20.0/24 192.168.100.5 0 100 80 777 888 999 i
*> 10.10.30.0/24 192.168.100.5 0 100 80 i
*> 10.10.40.0/24 192.168.100.5 0 100 80 i
*> 10.10.50.0/24 192.168.100.5 0 100 80 i
R2#configure terminal
R2(config)#router bgp 100
R2(config-router)# aggregate-address 10.10.0.0 255.255.0.0 suppress-map SUPP
attribute-map ATTRIBUTE as-set
R3#show ip bgp
BGP table version is 91, local router ID is 172.17.0.3
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
*> 10.10.0.0/16 192.168.100.5 0 0 100 {80,1000,2000,3000,777,888,999} i
*> 10.10.10.0/24 192.168.100.5 0 100 80 1000 2000 3000 i
*> 10.10.20.0/24 192.168.100.5 0 100 80 777 888 999 i
*> 10.10.30.0/24 192.168.100.5 0 100 80 i
*> 10.10.40.0/24 192.168.100.5 0 100 80 i
*> 10.10.50.0/24 192.168.100.5 0 100 80 i
The two as-path attributes of 10.10.10.0/24 and 10.10.20.0/24 build the AS-SET for the aggregated prefix.
The as-path will consist of the "AS Numbers" matched in a "ip as-path access-list".
R2#configure terminal
R2(config)#ip as-path access-list 1 deny _1000_
R2(config)#ip as-path access-list 1 permit .*
R2(config)#route-map AS-SET permit 10
R2(config-route-map)#match as-path 1
R2(config-route-map)#exit
R2(config)#router bgp 100
R2(config-router)# aggregate-address 10.10.0.0 255.255.0.0 suppress-map SUPP
attribute-map ATTRIBUTE as-set advertise-map AS-SET
The BGP table should now reflect our configuration. The complete AS-PATH for the prefix 10.10.10.0/24 is taken out of the AS-SET for the aggregate route.
R3#show ip bgp
BGP table version is 104, local router ID is 172.17.0.3
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
*> 10.10.0.0/16 192.168.100.5 0 0 100 {80,777,888,999} i
*> 10.10.10.0/24 192.168.100.5 0 100 80 1000 2000 3000 i
*> 10.10.20.0/24 192.168.100.5 0 100 80 777 888 999 i
*> 10.10.30.0/24 192.168.100.5 0 100 80 i
*> 10.10.40.0/24 192.168.100.5 0 100 80 i
*> 10.10.50.0/24 192.168.100.5 0 100 80 i
This brings the tutorial to an end.
Part 1, Setup
Part 2, Setting the Aggregate
Part 3, Component Routes
Part 4, Unsuppress the Suppressed
Part 5, Modification of Attributes
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