The aggregate is set without any parameters other than the prefix. BGP sends the aggregate to all other BGP speaking routers, including R1. As R1 is the source of all component routes of the aggregate it makes no sense to see the aggregate in R1. A prefix-list helps to stop the announcement of the aggregate to R1.
R2#configure terminal
R2(config)#router bgp 100
R2(config-router)#aggregate-address 10.10.0.0 255.255.0.0
The 10.10.0.0/16 prefix is now in the BGP tableof R1.
R1#sh ip bgp
BGP table version is 14, local router ID is 172.17.0.1
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
*> 10.10.0.0/16 192.168.100.2 0 0 100 i
*> 10.10.10.0/24 0.0.0.0 0 32768 i
... output omitted ...
A prefix-list denying 10.10.0.0/16 and allowing the rest is configured and bound to the BGP session to R1. 0.0.0.0/0 le 32 means all prefixes fo all sizes, or "the internet".
R2(config)#ip prefix-list NO-AGG-R1 deny 10.10.0.0/16
R2(config)#ip prefix-list NO-AGG-R1 permit 0.0.0.0/0 le 32
R2(config)#router bgp 100
R2(config-router)#neighbor 192.168.100.1 prefix-list NO-AGG-R1 out
R2(config-router)#end
R2#clear ip bgp 192.168.100.1 soft out
R1#sh ip bgp
BGP table version is 15, local router ID is 172.17.0.1
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
*> 10.10.10.0/24 0.0.0.0 0 32768 i
... output omitted ...
The other routers still see the aggregate and all of the component routes.
R4#show ip bgp
BGP table version is 14, local router ID is 172.17.0.4
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
*> 10.10.0.0/16 192.168.100.9 0 0 100 i
*> 10.10.10.0/24 192.168.100.9 0 100 80 1000 2000 3000 i
*> 10.10.11.0/24 192.168.100.9 0 100 80 i
*> 10.10.20.0/24 192.168.100.9 0 100 80 777 888 999 i
... output omitted ...
Part 1, Setup
Part 3, Component Routes
Part 4, Unsuppress the Suppressed
Part 5, Modification of Attributes
Part 6, Playing with the AS-SET
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