- configure the topology as per the diagram.
- configure EBGP as per the topology and advertise directly connected interfaces
- configure router 2 to block 30.1.1.1/8 networks. make sure router 2 do not install 30.1.1.1/8 network in its routing table.
- configure in order to block 30.1.1.1/8 network.
R1#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 10.1.1.1 YES manual up up
Serial3/0 1.1.1.1 YES manual up up
Serial3/3 4.1.1.2 YES manual up up
Loopback0 11.0.0.1 YES manual up up
Loopback1 11.0.1.1 YES manual up up
Loopback2 11.0.2.1 YES manual up up
Loopback3 11.0.3.1 YES manual up up
R2#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 20.1.1.1 YES manual up up
Serial3/0 1.1.1.2 YES manual up up
Serial3/1 2.1.1.1 YES manual up up
Loopback0 12.0.0.1 YES manual up up
Loopback1 12.0.1.1 YES manual up up
Loopback2 12.0.2.1 YES manual up up
Loopback3 12.0.3.1 YES manual up up
R3#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 30.1.1.1 YES manual up up
Serial3/1 2.1.1.2 YES manual up up
Serial3/2 3.1.1.1 YES manual up up
Loopback0 13.0.0.1 YES manual up up
Loopback1 13.0.1.1 YES manual up up
Loopback2 13.0.2.1 YES manual up up
Loopback3 13.0.3.1 YES manual up up
R4#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 40.1.1.1 YES manual up up
Serial3/2 3.1.1.2 YES manual up up
Serial3/3 4.1.1.1 YES manual up up
Loopback0 14.0.0.1 YES manual up up
Loopback1 14.0.1.1 YES manual up up
Loopback2 14.0.2.1 YES manual up up
Loopback3 14.0.3.1 YES manual up up
R1(config)#router bgp 650001
R1(config-router)#neighbor 1.1.1.2 remote-as 650002
R1(config-router)#neighbor 4.1.1.1 remote-as 650004
R1(config-router)#network 10.0.0.0
R1(config-router)#network 1.0.0.0
R1(config-router)#network 4.0.0.0
R1(config-router)#end
R2(config)#router bgp 650002
R2(config-router)#neighbor 1.1.1.1 remote-as 650001
R2(config-router)#neighbor 2.1.1.2 remote-as 650003
R2(config-router)#network 20.0.0.0
R2(config-router)#network 2.0.0.0
R2(config-router)#network 1.0.0.0
R2(config-router)#end
R3(config)#router bgp 650003
R3(config-router)#neighbor 2.1.1.1 remote-as 650002
R3(config-router)#neighbor 2.1.1. remote-as 650004
R3(config-router)#neighbor 3.1.1.2 remote-as 650004
R3(config-router)#network 30.0.0.0
R3(config-router)#network 3.0.0.0
R3(config-router)#network 2.0.0.0
R3(config-router)#end
R4(config)#router bgp 650004
R4(config-router)#neighbor 3.1.1.1 remote-as 650003
R4(config-router)#neighbor 4.1.1.2 remote-as 650001
R4(config-router)#network 40.0.0.0
R4(config-router)#network 4.0.0.0
R4(config-router)#network 3.0.0.0
R4(config-router)#endR1#show ip bgp
BGP table version is 16, local router ID is 11.0.3.1
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
* 1.0.0.0 1.1.1.2 0 0 650002 i
*> 0.0.0.0 0 32768 i
*> 2.0.0.0 1.1.1.2 0 0 650002 i
* 4.1.1.1 0 650004 650003 i
* 3.0.0.0 1.1.1.2 0 650002 650003 i
*> 4.1.1.1 0 0 650004 i
*> 4.0.0.0 0.0.0.0 0 32768 i
*> 10.0.0.0 0.0.0.0 0 32768 i
*> 20.0.0.0 1.1.1.2 0 0 650002 i
* 30.0.0.0 1.1.1.2 0 650002 650003 i
*> 4.1.1.1 0 650004 650003 i
*> 40.0.0.0 4.1.1.1 0 0 650004 i
R2#show ip bgp
BGP table version is 14, local router ID is 12.0.3.1
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 1.0.0.0 0.0.0.0 0 32768 i
* 1.1.1.1 0 0 650001 i
*> 2.0.0.0 0.0.0.0 0 32768 i
* 2.1.1.2 0 0 650003 i
*> 3.0.0.0 2.1.1.2 0 0 650003 i
* 1.1.1.1 0 650001 650004 i
* 4.0.0.0 2.1.1.2 0 650003 650004 650001 i
*> 1.1.1.1 0 0 650001 i
* 10.0.0.0 2.1.1.2 0 650003 650004 650001 i
*> 1.1.1.1 0 0 650001 i
*> 20.0.0.0 0.0.0.0 0 32768 i
*> 30.0.0.0 2.1.1.2 0 0 650003 i
Network Next Hop Metric LocPrf Weight Path
* 1.1.1.1 0 650001 650004 650003 i
* 40.0.0.0 2.1.1.2 0 650003 650004 i
*> 1.1.1.1 0 650001 650004 i
R3#show ip bgp
BGP table version is 16, local router ID is 13.0.3.1
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
*> 1.0.0.0 2.1.1.1 0 0 650002 i
* 3.1.1.2 0 650004 650001 i
* 2.0.0.0 2.1.1.1 0 0 650002 i
*> 0.0.0.0 0 32768 i
* 3.0.0.0 3.1.1.2 0 0 650004 i
*> 0.0.0.0 0 32768 i
* 4.0.0.0 2.1.1.1 0 650002 650001 i
*> 3.1.1.2 0 650004 650001 i
* 10.0.0.0 2.1.1.1 0 650002 650001 i
*> 3.1.1.2 0 650004 650001 i
* 20.0.0.0 3.1.1.2 0 650004 650001 650002 i
*> 2.1.1.1 0 0 650002 i
*> 30.0.0.0 0.0.0.0 0 32768 i
Network Next Hop Metric LocPrf Weight Path
* 40.0.0.0 2.1.1.1 0 650002 650001 650004 i
*> 3.1.1.2 0 0 650004 i
R4#show ip bgp
BGP table version is 15, local router ID is 14.0.3.1
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i – IGP, e – EGP, ? – incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
* 1.0.0.0 3.1.1.1 0 650003 650002 i
*> 4.1.1.2 0 0 650001 i
* 2.0.0.0 4.1.1.2 0 650001 650002 i
*> 3.1.1.1 0 0 650003 i
*> 3.0.0.0 0.0.0.0 0 32768 i
* 3.1.1.1 0 0 650003 i
*> 4.0.0.0 4.1.1.2 0 0 650001 i
*> 10.0.0.0 4.1.1.2 0 0 650001 i
* 20.0.0.0 3.1.1.1 0 650003 650002 i
*> 4.1.1.2 0 650001 650002 i
*> 30.0.0.0 3.1.1.1 0 0 650003 i
*> 40.0.0.0 0.0.0.0 0 32768 i
R2#show ip bgp 30.1.1.1
BGP routing table entry for 30.0.0.0/8, version 9
Paths: (2 available, best #1, table default)
Advertised to update-groups:
1
Refresh Epoch 2
650003
2.1.1.2 from 2.1.1.2 (13.0.3.1)
Origin IGP, metric 0, localpref 100, valid, external, best
rx pathid: 0, tx pathid: 0x0
Refresh Epoch 2
650001 650004 650003
1.1.1.1 from 1.1.1.1 (11.0.3.1)
Origin IGP, localpref 100, valid, external
rx pathid: 0, tx pathid: 0
(we are going block 30.1.1.1/8 network by using distribution list)
R2(config)#access-list 30 deny 30.1.1.1 0.255.255.255
R2(config)#access-list 30 permit any
R2(config)#exit
R2(config)#router bgp 650002
R2(config-router)#neighbor 2.1.1.2 distribute-list 30 in
R2(config-router)#neighbor 1.1.1.1 distribute-list 30 in
R2(config-router)#end
