Hi Guys,
This is killing me, I am not able to figure it out what is going on...
I have attached the "Topology.jpg" diagram.
R5 is the Core router in Active Data center & R3 is the Edge router in Active Data center
R4 is the Core router in Backup Data center & R2 is the Edge router in Backup Data center
R1 is a brance office connecting to Edge routers in Active / Backup Data Centers.
R2 is redistribuing the static route for the subnet 100.100.100.0/24 over OSPF to R4
R3 is redistribuing the static route for the subnet 100.100.100.0/24 over OSPF to R5
R5 is redistributing the OSPF routes into BGP towards R4
R4 is redistributing the OSPF routes into BGP towards R5
Normal traffic flow
R5 => R3 => R1
R4 => R5 => R3 => R1
When the link between R1 & R3 goes down.
R5 => R4 => R2 => R1
R4 => R2 => R1
R2 Config
interface FastEthernet0/0
ip address 10.10.10.2 255.255.255.0
speed auto
duplex auto
!
interface FastEthernet0/1
ip address 10.128.52.1 255.255.255.0
speed auto
duplex auto
!
router ospf 120
router-id 10.128.52.1
redistribute static metric 100 subnets route-map static_to_ospf
passive-interface default
no passive-interface FastEthernet0/1
network 10.128.52.0 0.0.0.255 area 0
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
ip route 0.0.0.0 0.0.0.0 10.10.10.1
ip route 100.100.100.0 255.255.255.0 10.10.10.1
!
ip access-list standard static_to_ospf
permit 100.100.100.0 0.0.0.255 log
!
!
route-map static_to_ospf permit 10
match ip address static_to_ospf
R3 Config
interface FastEthernet0/0
ip address 10.128.4.1 255.255.255.0
speed auto
duplex auto
!
interface FastEthernet0/1
ip address 11.11.11.2 255.255.255.0
speed auto
duplex auto
!
router ospf 120
router-id 10.128.4.1
redistribute static subnets route-map static_to_ospf
passive-interface default
no passive-interface FastEthernet0/0
network 10.128.4.0 0.0.0.255 area 0
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
ip route 0.0.0.0 0.0.0.0 11.11.11.1
ip route 100.100.100.0 255.255.255.0 11.11.11.1
!
ip access-list standard static_to_ospf
permit 100.100.100.0 0.0.0.255 log
!
!
route-map static_to_ospf permit 10
match ip address static_to_ospf
R4 Config
interface FastEthernet0/0
ip address 1.1.1.1 255.255.255.0
speed auto
duplex auto
!
interface FastEthernet0/1
ip address 10.128.52.2 255.255.255.0
speed auto
duplex auto
!
router ospf 120
router-id 10.128.52.2
passive-interface default
no passive-interface FastEthernet0/1
network 10.128.52.0 0.0.0.255 area 0
distance 200 10.128.52.1 0.0.0.0
!
router bgp 100
bgp log-neighbor-changes
network 1.1.1.0 mask 255.255.255.0
redistribute ospf 120 route-map VPN-Net-10-to-BGP
neighbor 1.1.1.2 remote-as 200
neighbor 1.1.1.2 next-hop-self all
neighbor 1.1.1.2 soft-reconfiguration inbound
!
ip access-list standard VPN-Net-10-to-BGP
permit 100.100.100.0 0.0.0.255
!
!
route-map VPN-Net-10-to-BGP permit 10
match ip address VPN-Net-10-to-BGP
R5 Config
interface FastEthernet0/0
ip address 10.128.4.2 255.255.255.0
speed auto
duplex auto
!
interface FastEthernet0/1
ip address 1.1.1.2 255.255.255.0
speed auto
duplex auto
!
router ospf 120
router-id 10.128.4.2
passive-interface default
no passive-interface FastEthernet0/0
network 10.128.4.0 0.0.0.255 area 0
!
router bgp 200
bgp log-neighbor-changes
network 1.1.1.0 mask 255.255.255.0
redistribute ospf 120 route-map VPN-Net-10-to-BGP
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 next-hop-self all
neighbor 1.1.1.1 soft-reconfiguration inbound
default-information originate
distance 190 1.1.1.1 0.0.0.0
!
ip access-list standard VPN-Net-10-to-BGP
permit 100.100.100.0 0.0.0.255
!
!
route-map VPN-Net-10-to-BGP permit 10
match ip address VPN-Net-10-to-BGP
R5 is learning the route for 100.100.100.0/24 through R3 over OSPF. When I shutdown the link between R1 & R3, R5 is learning the route via R4 over BGP. Again When I give the command "no shutdown" as expected R5 is learning the route for 100.100.100.0/24 through R3 over OSPF.
As OSPF is having the AD of 110 when compared to BGP AD of 190. No Problem in Active Datacenter.
The problem starts in Backup Datacenter.
Even though OSPF is having a higer AD than BGP, I have increated the AD to 200 and metric to 100 for the OSPF routes.
When the link between R3 & R1 comes up, the OSPF route is not getting removed on R4 even though it is receiving BGP route with distance & metric as 20/20. Not sure why?
R4#show ip route
Gateway of last resort is not set
1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 1.1.1.0/24 is directly connected, FastEthernet0/0
L 1.1.1.1/32 is directly connected, FastEthernet0/0
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.128.52.0/24 is directly connected, FastEthernet0/1
L 10.128.52.2/32 is directly connected, FastEthernet0/1
100.0.0.0/24 is subnetted, 1 subnets
O E2 100.100.100.0 [200/100] via 10.128.52.1, 00:41:43, FastEthernet0/1
R4#show ip bgp neighbors 1.1.1.2 received-routes
BGP table version is 4, local router ID is 10.128.52.2
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
* 1.1.1.0/24 1.1.1.2 0 0 200 i
* 100.100.100.0/24 1.1.1.2 20 0 200 ?
When I shutdown the link between R1 & R2, I am able to see the BGP route for the subnet 100.100.100.0/24 on R4. (Via R5 Active Datacenter)
But R5 is working perfectly fine. Please advice. Thanks in Advance.
