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

In this post OSPF will again be the PE to CE routing-protocol. The only difference with the previous post is that the OSPF PID between router R3 and R7 will be 20.

Below the diagram again :

MPLS


The changes made on router R3 and R7 below :

R3 :


router ospf 20 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 20 vrf VPN_A match internal external 1 external 2
 no auto-summary
 no synchronization
 exit-address-family

R7 :


router ospf 20
 router-id 7.7.7.7
 log-adjacency-changes
 redistribute connected subnets
 network 37.37.37.7 0.0.0.0 area 0

The “show ip route” output on router R7 before changing the PID from 10 (like configured in the previous post) to 20 on router R3 and R7 :

R7 :


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, 00:02:19, FastEthernet1/3
     61.0.0.0/24 is subnetted, 1 subnets
O IA    61.61.61.0 [110/2] via 37.37.37.3, 00:02:19, FastEthernet1/3

After changing the PID to 20 the “show ip route” output on router R7 looks like below , notice that now all routes are seen as external routes.

The “show ip route” output on router R7 after changing the PID on router R3 and R7 :

R7 :


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, 00:00:59, FastEthernet1/3
     61.0.0.0/24 is subnetted, 1 subnets
O E2    61.61.61.0 [110/1] via 37.37.37.3, 00:00:59, FastEthernet1/3

1 Comment

shivlu jainApril 1st, 2009 at 4:41 pm

Hi

Good doc , I have posted the same on my blog also.

http://shivlu.blogspot.com/2008/11/why-ospf-vpnv4-routes-look-as-external_07.html

This can be overcome by chaging domain-id with no downtime. Because by default pid works as domain id. So we need to make the domain-id same and consequence no e2 routes. :)

regards
shivlu jain

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