CE-PE: IGP – OSPF
As always, I will start with the remote sites to configure OSPF.
R9
interface Loopback9
ip address 9.9.9.9 255.255.255.255
!
interface Loopback99
ip address 99.99.99.1 255.255.255.0
!
interface FastEthernet0/0
ip address 172.16.89.2 255.255.255.0
speed 100
full-duplex
!
router ospf 20
router-id 9.9.9.9
log-adjacency-changes
no auto-cost
network 99.99.99.0 0.0.0.255 area 0
network 172.16.89.0 0.0.0.255 area 0
!
R14
interface Loopback14
ip address 14.14.14.1 255.255.255.0
!
interface FastEthernet0/0
ip address 172.16.34.2 255.255.255.0
speed 100
full-duplex
!
router ospf 20
network 14.14.14.0 0.0.0.255 area 0
network 172.16.34.0 0.0.0.255 area 0
!
Next step is configuring the PEs facing the CEs.
R8
router ospf 20 vrf CUSTB100
redistribute bgp 100 subnets
network 172.16.89.0 0.0.0.255 area 0
!
router bgp 100
address-family ipv4 vrf CUSTB100
redistribute ospf 20 vrf CUSTB100
no synchronization
exit-address-family
!
R13
router ospf 20 vrf CUSTB222
redistribute bgp 100 subnets
network 172.16.34.0 0.0.0.255 area 0
!
router bgp 100
address-family ipv4 vrf CUSTB222
redistribute ospf 20 vrf CUSTB222
no synchronization
exit-address-family
!
As you noticed, the command special OSPF VRF command “router ospf process-id vrf” which differs from how EIGRP VRF is configured as we saw in the EIGRP post. Of course, you will need to redistribute OSPF 20 into BGP and vice versa.
Verifying OSPF is established between the PEs and CEs. Note that, unlike EIGRP, there is no VRF-specific OSPF show command:
Final step is to configure ISP PEs facing the other ISP PEs.
R5:
router bgp 100
address-family ipv4 vrf CUSTB100
neighbor 172.16.152.1 remote-as 500
neighbor 172.16.152.1 activate
neighbor 172.16.152.1 as-override
neighbor 172.16.152.1 soft-reconfiguration inbound
no synchronization
exit-address-family
!
R1:
router bgp 500
address-family ipv4 vrf CUSTB500
neighbor 172.16.152.2 remote-as 100
neighbor 172.16.152.2 activate
neighbor 172.16.152.2 as-override
neighbor 172.16.152.2 soft-reconfiguration inbound
no synchronization
exit-address-family
!
R4:
router bgp 500
address-family ipv4 vrf CUSTB500
neighbor 172.16.142.2 remote-as 100
neighbor 172.16.142.2 activate
neighbor 172.16.142.2 as-override
neighbor 172.16.142.2 soft-reconfiguration inbound
no synchronization
exit-address-family
!
R10:
router bgp 100
address-family ipv4 vrf CUSTB222
neighbor 172.16.142.1 remote-as 500
neighbor 172.16.142.1 activate
neighbor 172.16.142.1 as-override
neighbor 172.16.142.1 soft-reconfiguration inbound
no synchronization
exit-address-family
!
Let’s confirm that each remote router is learning the networks behind the other remote router and that site to site connectivity is present:
