MPLS VPN implementation requires VRF and also exporting and importing routes for that VRF.
I mentioned on my previous posts about VRF that the VRF name is locally significant and even the RD number.
What counts is what you import and export.
Importing and exporting route targets use the same syntax as the RD and it is ASN:NN
as shown by the example below :
ip vrf ALL-VRF
rd 123:4
route-target export 123:4
route-target import 123:1
route-target import 123:2
route-target import 123:3
By definition the routes that you “export” are only the routes you advertise on the
vrf address family in BGP. The routes that you import are the cummulative routes with
the same label that were exported from the other routers participating in the MPLS VPN.
Remember that you don’t export what you have learned through importation.
In a VRF you can export and import as many route-targets as needed.
Lets see if RR can see the routes now :
RR
!
ip vrf ALL-VRF
rd 123:4
route-target export 123:4
route-target import 123:1
route-target import 123:2
route-target import 123:3
RR#sh ip route vrf ALL-VRF
Routing Table: ALL-VRF
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
1.0.0.0/32 is subnetted, 1 subnets
B 1.1.1.1 [200/0] via 123.123.123.1, 00:46:26
2.0.0.0/32 is subnetted, 1 subnets
B 2.2.2.2 [200/0] via 123.123.123.2, 00:46:26
33.0.0.0/32 is subnetted, 1 subnets
B 33.33.33.33 [200/0] via 123.123.123.3, 00:46:26
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [200/0] via 123.123.123.3, 00:46:26
22.0.0.0/32 is subnetted, 1 subnets
B 22.22.22.22 [200/0] via 123.123.123.2, 00:46:26
11.0.0.0/32 is subnetted, 1 subnets
B 11.11.11.11 [200/0] via 123.123.123.1, 00:46:28
123.0.0.0/32 is subnetted, 1 subnets
C 123.123.123.14 is directly connected, Loopback40
Scenario Conditions :
1. EMEA should have full ip reachability to APAC and AMERICAS but APAC and AMERICAS
should not see each other.
2. RR should only see the all the routes but will not be seen by the routers.
Below are the VRF configurations on the 3 clients.
APAC#
!
ip vrf APAC
rd 123:1
route-target export 123:1
route-target import 123:2
AMERICAS#
!
ip vrf AMERICAS
rd 123:2
route-target export 123:2
route-target import 123:2
EMEA#
!
ip vrf EMEA
rd 123:3
route-target export 123:3
route-target export 123:2
route-target import 123:4
route-target import 123:2
APAC is exporting route-target 123:1 and its importing 123:3 which is exported by EMEA.
EMEA on the other hand is importing 123:1 and exporting 123:3. There should be full ip
reachability between the two.
By the way the route-target ID doesn’t necessarily match with the RD. Normally for networks that should
see each other in MPLS VPN both the export and import route target ID’s are the same.
It will get rid of any unnecessary confusion created by using different RT ID’s.
Take into consideration AMERICAS and EMEA routers.
As you can see on the config above,
AMERICAS is importing and exporting 123:2.
One command can generate the both export and import and that is “route-target both 123:2“.
EMEA is importing and exporting also 123:2 which means they will reach each other.
Let’s test if we have accomplished the condition, we will show the routing table in
APAC and AMERICAS and let’s ping the networks in EMEA.
The ping should be sourced on the loopback interfaces where we configured the VRF’s.
APAC#sh ip route vrf APAC
Routing Table: APAC
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
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
33.0.0.0/32 is subnetted, 1 subnets
B 33.33.33.33 [200/0] via 123.123.123.3, 01:04:51
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [200/0] via 123.123.123.3, 01:04:51
11.0.0.0/32 is subnetted, 1 subnets
C 11.11.11.11 is directly connected, Loopback10
APAC#ping vrf APAC 3.3.3.3 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
Packet sent with a source address of 1.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 248/346/436 ms
AMERICAS#sh ip route vrf AMERICAS
Routing Table: AMERICAS
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
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback0
33.0.0.0/32 is subnetted, 1 subnets
B 33.33.33.33 [200/0] via 123.123.123.3, 00:56:20
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [200/0] via 123.123.123.3, 00:56:20
22.0.0.0/32 is subnetted, 1 subnets
C 22.22.22.22 is directly connected, Loopback10
AMERICAS#ping vrf AMERICAS 3.3.3.3 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
Packet sent with a source address of 2.2.2.2
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 184/593/1020 ms
EMEA#sh ip route vrf EMEA
Routing Table: EMEA
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
1.0.0.0/32 is subnetted, 1 subnets
B 1.1.1.1 [200/0] via 123.123.123.1, 00:00:00
2.0.0.0/32 is subnetted, 1 subnets
B 2.2.2.2 [200/0] via 123.123.123.2, 01:07:06
33.0.0.0/32 is subnetted, 1 subnets
C 33.33.33.33 is directly connected, Loopback10
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
22.0.0.0/32 is subnetted, 1 subnets
B 22.22.22.22 [200/0] via 123.123.123.2, 01:07:06
11.0.0.0/32 is subnetted, 1 subnets
B 11.11.11.11 [200/0] via 123.123.123.1, 00:00:03
It will take a while to get used to VRF Route-target if you are just learning it but this
should be pretty easy. Remember, you can’t reach a network that you have imported unless
it exported your network. In MPLS VRF, entries in your VRF routing table doesn’t assure
reachability, the router in the destination network should also have your network in its
VRF routing table.
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