BGP IPv4 - Confederation
Confederation
BGP (Border Gateway Protocol) IPv4 Confederation is a mechanism used to address scalability challenges in large and complex autonomous systems. In traditional BGP, all routers within an autonomous system (AS) must maintain a full mesh of BGP peer connections, leading to potential scaling issues as the number of routers increases. IPv4 BGP Confederations offer a solution by dividing the AS into smaller sub-AS groups, each known as a confederation. Within these confederations, routers maintain a full mesh of BGP connections, but routers in different confederations only need to establish connections with the routers in their own confederation and the confederation's external peers. This approach simplifies the BGP topology and enhances scalability, making it more manageable for large-scale networks. BGP Confederation allows for better control of route propagation, reducing the complexity of BGP peering relationships and improving the overall efficiency of BGP in diverse and extensive network environments.
Lab:
BGP Topology
Disclaimer
This Configuration Guide is designed to assist members to enhance their skills in particular technology area. While every effort has been made to ensure that all material is as complete and accurate as possible, the enclosed material is presented on an “as is” basis. Neither the authors nor Forum assume any liability or responsibility to any person or entity with respect to loss or damages incurred from the information contained in this guide. This configuration guide was developed by Forum. Any similarities between material presented in this configuration guide and any other material is completely coincidental. Cisco IOS Software, Linux Software (I86BI_LINUX-ADVENTERPRISEK9-M), Version 15.2(4)M1, DEVELOPMENT TEST SOFTWARE
Task 1: Configure IPv4 BGP Process for Autonomous
R1:
router bgp 100
neighbor 12.0.0.2 remote-as 65002
neighbor 12.0.0.2 soft-reconfiguration inbound
address-family ipv4
network 11.0.1.0 mask 255.255.255.0
network 11.0.2.0 mask 255.255.255.0
network 11.0.3.0 mask 255.255.255.0
exit
R2:
router bgp 65002
neighbor 23.0.0.3 remote-as 65001
neighbor 23.0.0.3 soft-reconfiguration inbound
neighbor 12.0.0.1 remote-as 100
neighbor 12.0.0.1 soft-reconfiguration inbound
address-family ipv4
network 22.0.1.0 mask 255.255.255.0
network 22.0.2.0 mask 255.255.255.0
network 22.0.3.0 mask 255.255.255.0
exit
R3:
router bgp 65001
neighbor 23.0.0.2 remote-as 65002
neighbor 23.0.0.2 soft-reconfiguration inbound
neighbor 34.0.0.4 remote-as 65001
neighbor 34.0.0.4 soft-reconfiguration inbound
address-family ipv4
network 33.0.1.0 mask 255.255.255.0
network 33.0.2.0 mask 255.255.255.0
network 33.0.3.0 mask 255.255.255.0
exit
R4:
router bgp 65001
neighbor 34.0.0.3 remote-as 65001
neighbor 34.0.0.3 soft-reconfiguration inbound
address-family ipv4
network 44.0.1.0 mask 255.255.255.0
network 44.0.2.0 mask 255.255.255.0
network 44.0.3.0 mask 255.255.255.0
exit
Step 2: In the configuration mode of router configure IPv4 OSPF Process by following command:
R1:
router ospf 1
network 0.0.0.0 0.0.0.0 area 0
exit
R2:
router ospf 1
network 0.0.0.0 0.0.0.0 area 0
exit
R3:
router ospf 1
network 0.0.0.0 0.0.0.0 area 0
exit
R4:
router ospf 1
network 0.0.0.0 0.0.0.0 area 0
exit
Step 3: Verify IPv4 BGP routes by following command:
R1#show ip bgp
BGP table version is 13, 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
*> 11.0.1.0/24 0.0.0.0 0 32768 i
*> 11.0.2.0/24 0.0.0.0 0 32768 i
*> 11.0.3.0/24 0.0.0.0 0 32768 i
*> 22.0.1.0/24 12.0.0.2 0 0 65002 i
*> 22.0.2.0/24 12.0.0.2 0 0 65002 i
*> 22.0.3.0/24 12.0.0.2 0 0 65002 i
*> 33.0.1.0/24 12.0.0.2 0 65002 65001 i
*> 33.0.2.0/24 12.0.0.2 0 65002 65001 i
*> 33.0.3.0/24 12.0.0.2 0 65002 65001 i
*> 44.0.1.0/24 12.0.0.2 0 65002 65001 i
*> 44.0.2.0/24 12.0.0.2 0 65002 65001 i
*> 44.0.3.0/24 12.0.0.2 0 65002 65001 i
R2#show ip bgp
BGP table version is 13, local router ID is 22.0.3.2
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
*> 11.0.1.0/24 12.0.0.1 0 0 100 i
*> 11.0.2.0/24 12.0.0.1 0 0 100 i
*> 11.0.3.0/24 12.0.0.1 0 0 100 i
*> 22.0.1.0/24 0.0.0.0 0 32768 i
*> 22.0.2.0/24 0.0.0.0 0 32768 i
*> 22.0.3.0/24 0.0.0.0 0 32768 i
*> 33.0.1.0/24 23.0.0.3 0 0 65001 i
*> 33.0.2.0/24 23.0.0.3 0 0 65001 i
*> 33.0.3.0/24 23.0.0.3 0 0 65001 i
*> 44.0.1.0/24 23.0.0.3 0 65001 i
*> 44.0.2.0/24 23.0.0.3 0 65001 i
*> 44.0.3.0/24 23.0.0.3 0 65001 i
R3#show ip bgp
BGP table version is 13, local router ID is 33.0.3.3
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
*> 11.0.1.0/24 23.0.0.2 0 65002 100 i
*> 11.0.2.0/24 23.0.0.2 0 65002 100 i
*> 11.0.3.0/24 23.0.0.2 0 65002 100 i
*> 22.0.1.0/24 23.0.0.2 0 0 65002 i
*> 22.0.2.0/24 23.0.0.2 0 0 65002 i
*> 22.0.3.0/24 23.0.0.2 0 0 65002 i
*> 33.0.1.0/24 0.0.0.0 0 32768 i
*> 33.0.2.0/24 0.0.0.0 0 32768 i
*> 33.0.3.0/24 0.0.0.0 0 32768 i
*>i 44.0.1.0/24 34.0.0.4 0 100 0 i
*>i 44.0.2.0/24 34.0.0.4 0 100 0 i
*>i 44.0.3.0/24 34.0.0.4 0 100 0 i
R4#show ip bgp
BGP table version is 13, local router ID is 44.0.3.4
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
*>i 11.0.1.0/24 23.0.0.2 0 100 0 65002 100 i
*>i 11.0.2.0/24 23.0.0.2 0 100 0 65002 100 i
*>i 11.0.3.0/24 23.0.0.2 0 100 0 65002 100 i
*>i 22.0.1.0/24 23.0.0.2 0 100 0 65002 i
*>i 22.0.2.0/24 23.0.0.2 0 100 0 65002 i
*>i 22.0.3.0/24 23.0.0.2 0 100 0 65002 i
*>i 33.0.1.0/24 34.0.0.3 0 100 0 i
*>i 33.0.2.0/24 34.0.0.3 0 100 0 i
*>i 33.0.3.0/24 34.0.0.3 0 100 0 i
*> 44.0.1.0/24 0.0.0.0 0 32768 i
*> 44.0.2.0/24 0.0.0.0 0 32768 i
*> 44.0.3.0/24 0.0.0.0 0 32768 i
Task 2: Configure IPv4 BGP Confederation
Step 1: In the configuration mode of router configure IPv4 BGP confederation by following command:
R1:
router bgp 100
neighbor 12.0.0.2 remote-as 200
exit
R2:
router bgp 65002
bgp confederation identifier 200
bgp confederation peers 65001
exit
R3:
router bgp 65001
bgp confederation identifier 200
bgp confederation peers 65002
exit
R4:
router bgp 65001
bgp confederation identifier 200
exit
Step 2: Verify IPv4 BGP routes by following command:
R1#show ip bgp
BGP table version is 13, 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
*> 11.0.1.0/24 0.0.0.0 0 32768 i
*> 11.0.2.0/24 0.0.0.0 0 32768 i
*> 11.0.3.0/24 0.0.0.0 0 32768 i
*> 22.0.1.0/24 12.0.0.2 0 0 200 i
*> 22.0.2.0/24 12.0.0.2 0 0 200 i
*> 22.0.3.0/24 12.0.0.2 0 0 200 i
*> 33.0.1.0/24 12.0.0.2 0 200 i
*> 33.0.2.0/24 12.0.0.2 0 200 i
*> 33.0.3.0/24 12.0.0.2 0 200 i
*> 44.0.1.0/24 12.0.0.2 0 200 i
*> 44.0.2.0/24 12.0.0.2 0 200 i
*> 44.0.3.0/24 12.0.0.2 0 200 i
R2#show ip bgp
BGP table version is 13, local router ID is 22.0.3.2
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
*> 11.0.1.0/24 12.0.0.1 0 0 100 i
*> 11.0.2.0/24 12.0.0.1 0 0 100 i
*> 11.0.3.0/24 12.0.0.1 0 0 100 i
*> 22.0.1.0/24 0.0.0.0 0 32768 i
*> 22.0.2.0/24 0.0.0.0 0 32768 i
*> 22.0.3.0/24 0.0.0.0 0 32768 i
*> 33.0.1.0/24 23.0.0.3 0 100 0 (65001) i
*> 33.0.2.0/24 23.0.0.3 0 100 0 (65001) i
*> 33.0.3.0/24 23.0.0.3 0 100 0 (65001) i
*> 44.0.1.0/24 34.0.0.4 0 100 0 (65001) i
*> 44.0.2.0/24 34.0.0.4 0 100 0 (65001) i
*> 44.0.3.0/24 34.0.0.4 0 100 0 (65001) i
R3#show ip bgp
BGP table version is 25, local router ID is 33.0.3.3
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
*> 11.0.1.0/24 12.0.0.1 0 100 0 (65002) 100 i
*> 11.0.2.0/24 12.0.0.1 0 100 0 (65002) 100 i
*> 11.0.3.0/24 12.0.0.1 0 100 0 (65002) 100 i
*> 22.0.1.0/24 23.0.0.2 0 100 0 (65002) i
*> 22.0.2.0/24 23.0.0.2 0 100 0 (65002) i
*> 22.0.3.0/24 23.0.0.2 0 100 0 (65002) i
*> 33.0.1.0/24 0.0.0.0 0 32768 i
*> 33.0.2.0/24 0.0.0.0 0 32768 i
*> 33.0.3.0/24 0.0.0.0 0 32768 i
*>i 44.0.1.0/24 34.0.0.4 0 100 0 i
*>i 44.0.2.0/24 34.0.0.4 0 100 0 i
*>i 44.0.3.0/24 34.0.0.4 0 100 0 i
R4#show ip bgp
BGP table version is 25, local router ID is 44.0.3.4
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
*>i 11.0.1.0/24 12.0.0.1 0 100 0 (65002) 100 i
*>i 11.0.2.0/24 12.0.0.1 0 100 0 (65002) 100 i
*>i 11.0.3.0/24 12.0.0.1 0 100 0 (65002) 100 i
*>i 22.0.1.0/24 23.0.0.2 0 100 0 (65002) i
*>i 22.0.2.0/24 23.0.0.2 0 100 0 (65002) i
*>i 22.0.3.0/24 23.0.0.2 0 100 0 (65002) i
*>i 33.0.1.0/24 34.0.0.3 0 100 0 i
*>i 33.0.2.0/24 34.0.0.3 0 100 0 i
*>i 33.0.3.0/24 34.0.0.3 0 100 0 i
*> 44.0.1.0/24 0.0.0.0 0 32768 i
*> 44.0.2.0/24 0.0.0.0 0 32768 i
*> 44.0.3.0/24 0.0.0.0 0 32768 i
Task 3: Verify BGP Path Selection in BGP confederation
Step 1: In the configuration mode of router configure redundant path by following command:
R1:
interface ethernet 0/0
ip address 14.0.0.1 255.255.255.0
no shutdown
exit
router bgp 100
neighbor 14.0.0.4 remote-as 200
neighbor 14.0.0.4 soft-reconfiguration inbound
exit
R4:
interface ethernet 0/0
ip address 14.0.0.4 255.255.255.0
no shutdown
exit
router bgp 65001
neighbor 14.0.0.1 remote-as 100
neighbor 14.0.0.1 soft-reconfiguration inbound
exit
Step 2: Verify IPv4 BGP routes by following command:
R1#show ip bgp
BGP table version is 37, 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
*> 11.0.1.0/24 0.0.0.0 0 32768 i
*> 11.0.2.0/24 0.0.0.0 0 32768 i
*> 11.0.3.0/24 0.0.0.0 0 32768 i
* 22.0.1.0/24 14.0.0.4 0 200 i
*> 12.0.0.2 0 0 200 i
* 22.0.2.0/24 14.0.0.4 0 200 i
*> 12.0.0.2 0 0 200 i
* 22.0.3.0/24 14.0.0.4 0 200 i
*> 12.0.0.2 0 0 200 i
* 33.0.1.0/24 14.0.0.4 0 200 i
*> 12.0.0.2 0 200 i
* 33.0.2.0/24 14.0.0.4 0 200 i
*> 12.0.0.2 0 200 i
* 33.0.3.0/24 14.0.0.4 0 200 i
*> 12.0.0.2 0 200 i
* 44.0.1.0/24 14.0.0.4 0 0 200 i
*> 12.0.0.2 0 200 i
* 44.0.2.0/24 14.0.0.4 0 0 200 i
*> 12.0.0.2 0 200 i
* 44.0.3.0/24 14.0.0.4 0 0 200 i
*> 12.0.0.2 0 200 i
R1 is choosing 12.0.0.2 via R2 as best path instead of 14.0.0.4 to R4, R1 is choosing longest path as best path instead of choosing shortest path.
R1#traceroute 44.0.3.0
Type escape sequence to abort.
Tracing the route to 44.0.3.0
VRF info: (vrf in name/id, vrf out name/id)
1 12.0.0.2 8 msec 8 msec 9 msec
2 23.0.0.3 8 msec 9 msec 8 msec