MPLS LAB - PE to CE routing - OSPF (same PID)
January 16th, 2009 in CCIE SP | tags: ,

In this post I will configure OSPF as the PE to CE routing protocol. You can see the drawing below. Notice that for this post I will use the same proces-id’s between te PE’s and CE’s (PID 10).

The domain-id is derived from the proces-id but can also be manually set (More on this in the next post).

- When the domain-id’s match between the PE and CE’s like on the drawing below OSPF routes will show up as inter-area routes.

- When the domain-id’s do not match between the PE and CE’s like the drawing in the next post, OSPF routes will show up as external routes.

MPLS

Below the coniguration that goes with the drawing (I am only going to show the configuration for VPN_A again since the configuration for VPN_B is the same) :

Router R3 :

R3 :


router ospf 10 vrf VPN_A
 router-id 37.37.37.3
 log-adjacency-changes
 redistribute bgp 100 subnets
 network 37.37.37.3 0.0.0.0 area 0
!
router bgp 100
 no synchronization
 bgp router-id 3.3.3.3
 bgp log-neighbor-changes
 neighbor 6.6.6.6 remote-as 100
 neighbor 6.6.6.6 update-source Loopback0
 no auto-summary
 !
 address-family ipv4 vrf VPN_A
 redistribute ospf 10 vrf VPN_A match internal external 1 external 2
 no auto-summary
 no synchronization
 exit-address-family

Router R7 :

R7 :


router ospf 10
 router-id 7.7.7.7
 log-adjacency-changes
 redistribute connected subnets
 network 37.37.37.7 0.0.0.0 area 0

Router R6 :

R6 :


router ospf 10 vrf VPN_A
 router-id 61.61.61.6
 log-adjacency-changes
 redistribute bgp 100 subnets
 network 61.61.61.6 0.0.0.0 area 0
!
router bgp 100
 no synchronization
 bgp router-id 6.6.6.6
 bgp log-neighbor-changes
 neighbor 3.3.3.3 remote-as 100
 neighbor 3.3.3.3 update-source Loopback0
 no auto-summary
 !
 address-family ipv4 vrf VPN_A
 redistribute ospf 10 vrf VPN_A match internal external 1 external 2
 no auto-summary
 no synchronization
 exit-address-family

Router R11 :

R11 :


router ospf 10
 router-id 11.11.11.11
 log-adjacency-changes
 redistribute connected subnets
 network 61.61.61.11 0.0.0.0 area 0

Below the “show ip route” output on router R11 and R7 :

R7 and R11 :


R7#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     37.0.0.0/24 is subnetted, 1 subnets
C       37.37.37.0 is directly connected, FastEthernet1/3
     7.0.0.0/32 is subnetted, 1 subnets
C       7.7.7.7 is directly connected, Loopback0
     11.0.0.0/32 is subnetted, 1 subnets
O E2    11.11.11.11 [110/20] via 37.37.37.3, 00:10:11, FastEthernet1/3
     61.0.0.0/24 is subnetted, 1 subnets
O IA    61.61.61.0 [110/2] via 37.37.37.3, 00:11:11, FastEthernet1/3

R11#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     37.0.0.0/24 is subnetted, 1 subnets
O IA    37.37.37.0 [110/2] via 61.61.61.6, 00:08:29, FastEthernet2/0
     7.0.0.0/32 is subnetted, 1 subnets
O E2    7.7.7.7 [110/20] via 61.61.61.6, 00:08:29, FastEthernet2/0
     11.0.0.0/32 is subnetted, 1 subnets
C       11.11.11.11 is directly connected, Loopback0
     61.0.0.0/24 is subnetted, 1 subnets
C       61.61.61.0 is directly connected, FastEthernet2/0

As you can see external routes remain external and the routes from VPN site 1 show up as inter-area routes on VPN site 2.

In the next post I will configure OSPF as PE to CE routing protocol with different proces-id’s.

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