BGP Additional Path
default behavior: RR advertises only best path
- additional path can be used only in address family
- router can send or(and) receive addional path
- choose global selection criteria
- choose neighbors
Selection criteria
- Best N - first and second best path
- Group-best - set of path for each as
Before
R5# show ip bgp
BGP table version is 2, local router ID is 5.5.5.5
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 6.6.6.6/32 4.4.4.4 0 100 0 6 i
*> 192.168.56.6 0 0 6 i
R5#
R2#show ip bgp
BGP table version is 4, local router ID is 2.2.2.2
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
* i 6.6.6.6/32 5.5.5.5 0 100 0 6 i
*>i 4.4.4.4 0 100 0 6 i
R2#
R1#show ip bgp
BGP table version is 4, 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, 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 6.6.6.6/32 4.4.4.4 0 100 0 6 i
R1#
Additional config
R2(config)#router bgp 12345
R2(config-router)#address-family ipv4
R2(config-router-af)#bgp additional-paths ?
install Additional paths to install into RIB
select Selection criteria to pick the paths
R2(config-router-af)#bgp additional-paths install
R2(config-router-af)#do show ip bgp
BGP table version is 5, local router ID is 2.2.2.2
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
*bi 6.6.6.6/32 5.5.5.5 0 100 0 6 i
*>i 4.4.4.4 0 100 0 6 i
R2(config-router-af)#
R1#show ip bgp
BGP table version is 4, 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, 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 6.6.6.6/32 4.4.4.4 0 100 0 6 i
R1#
Config
R1
interface Loopback0
ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet0/0
ip address 192.168.12.1 255.255.255.0
!
interface FastEthernet1/0
ip address 192.168.13.1 255.255.255.0
!
router ospf 1
network 1.1.1.1 0.0.0.0 area 0
network 192.168.12.0 0.0.0.255 area 0
network 192.168.13.0 0.0.0.255 area 0
!
router bgp 12345
bgp router-id 1.1.1.1
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 12345
neighbor 2.2.2.2 update-source Loopback0
R2
interface Loopback0
ip address 2.2.2.2 255.255.255.255
!
interface FastEthernet0/0
ip address 192.168.12.2 255.255.255.0
!
interface FastEthernet1/0
ip address 192.168.24.2 255.255.255.0
!
interface FastEthernet3/0
ip address 192.168.23.2 255.255.255.0
!
router ospf 1
network 2.2.2.2 0.0.0.0 area 0
network 192.168.12.0 0.0.0.255 area 0
network 192.168.23.0 0.0.0.255 area 0
network 192.168.24.0 0.0.0.255 area 0
!
router bgp 12345
bgp router-id 2.2.2.2
bgp log-neighbor-changes
neighbor 1.1.1.1 remote-as 12345
neighbor 1.1.1.1 update-source Loopback0
neighbor 1.1.1.1 route-reflector-client
neighbor 3.3.3.3 remote-as 12345
neighbor 3.3.3.3 update-source Loopback0
neighbor 3.3.3.3 route-reflector-client
neighbor 4.4.4.4 remote-as 12345
neighbor 4.4.4.4 update-source Loopback0
neighbor 4.4.4.4 route-reflector-client
neighbor 5.5.5.5 remote-as 12345
neighbor 5.5.5.5 update-source Loopback0
neighbor 5.5.5.5 route-reflector-client
R3
interface Loopback0
ip address 3.3.3.3 255.255.255.255
!
interface FastEthernet0/0
ip address 192.168.13.3 255.255.255.0
!
interface FastEthernet1/0
ip address 192.168.23.3 255.255.255.0
!
interface FastEthernet3/0
ip address 192.168.35.3 255.255.255.0
!
router ospf 1
network 3.3.3.3 0.0.0.0 area 0
network 192.168.13.0 0.0.0.255 area 0
network 192.168.23.0 0.0.0.255 area 0
network 192.168.35.0 0.0.0.255 area 0
!
router bgp 12345
bgp router-id 3.3.3.3
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 12345
neighbor 2.2.2.2 update-source Loopback0
R4
interface Loopback0
ip address 4.4.4.4 255.255.255.0
!
interface FastEthernet0/0
ip address 192.168.24.4 255.255.255.0
!
interface FastEthernet1/0
ip address 192.168.45.4 255.255.255.0
!
interface FastEthernet3/0
ip address 192.168.46.4 255.255.255.0
!
router ospf 1
network 4.4.4.4 0.0.0.0 area 0
network 192.168.24.0 0.0.0.255 area 0
network 192.168.45.0 0.0.0.255 area 0
!
router bgp 12345
bgp router-id 4.4.4.4
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 12345
neighbor 2.2.2.2 update-source Loopback0
neighbor 2.2.2.2 next-hop-self
neighbor 192.168.46.6 remote-as 6
R5
interface Loopback0
ip address 5.5.5.5 255.255.255.255
!
interface FastEthernet0/0
ip address 192.168.35.5 255.255.255.0
!
interface FastEthernet1/0
ip address 192.168.45.5 255.255.255.0
!
interface FastEthernet3/0
ip address 192.168.56.5 255.255.255.0
!
router ospf 1
network 5.5.5.5 0.0.0.0 area 0
network 192.168.35.0 0.0.0.255 area 0
network 192.168.45.0 0.0.0.255 area 0
!
router bgp 12345
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 12345
neighbor 2.2.2.2 update-source Loopback0
neighbor 2.2.2.2 next-hop-self
neighbor 192.168.56.6 remote-as 6
R6
interface Loopback0
ip address 6.6.6.6 255.255.255.255
!
interface Loopback6
no ip address
!
interface FastEthernet0/0
ip address 192.168.46.6 255.255.255.0
duplex half
!
interface FastEthernet1/0
ip address 192.168.56.6 255.255.255.0
duplex half
!
interface GigabitEthernet2/0
no ip address
shutdown
negotiation auto
!
router bgp 6
bgp log-neighbor-changes
network 6.6.6.6 mask 255.255.255.255
neighbor 192.168.46.4 remote-as 12345
neighbor 192.168.56.5 remote-as 12345