MPLS: L3VPN ROUTE REDISTRIBUTION TO CE
The objective of this topic is to implement route redistribution to the CE router. We will be using the GNS3 configuration that we have on our previous topic MPLS: ROUTING BETWEEN THE CE AND PE.
The basic concept behind Route redistribution is for routers to learn the routes coming from a different routing protocol and thus be distributed to its own routing protocol.
Let's apply route redistribution on our topology wherein AAA is using OSPF on Location A and Location B but on Location C, RIP protocol was being used. While BBB uses EIGRP on Location A and Location B, Location C uses BGP to route its network.
Current configuration has:
running OSPF between VRF AAA (Location A) and PE-Location A
running EIGRP between VRF BBB (Location A) and PE-Location A
running OSPF between VRF AAA (Location B) and PE-Location B
running EIGRP between VRF BBB (Location B) and PE-Location B
running RIPv2 between VRF AAA (Location C) and PE-Location C
running BGP between VRF BBB (Location C) and PE-Location C
BGP is also running between PE-LocationA, PE-LocationB and PE-LocationC.
VRF deals with export/import of routes so keep in mind that an export is defined by a route that is taken out from the VRF and put into the BGP while import is defined as the route coming from the BGP and put into the VRF. In order for the import/export to function, a router should do mutual redistribution.
Let's start by doing a route export from the 100:AAA VRF and put into the BGP. This is done by creating an address-family ipv4 for the VRF 100:AAA. After that we will do a route redistribute learned from the OSPF and put it into BGP. This export process creates a VPNv4 route which will add the route distinguisher, route target and the VPN labels from the prefix.
The redistibute command will attach all the information such as the route, distinguisher, route-target and VPN labels to the VRF 100:AAA.
Verify the details of the VPNv4 RD labels
Verifying the forwarding table and next hop.
Forwarding table will show that the route is a VPN Path.
Verify the VRF routes on the VPN.
Verify the details of route which includes the Route distinguisher, route-target and VPN label.
Now let's proceed with the route import from BGP into the VRF 100:AAA.
Note: The redistribute will include the import value of 22.22.22.22:100 and 33.33.33.33:100.
Let's do the route export for the VRF 200:BBB. Again, as the route is being exported to VPNv4, the route distinguisher, route-target and VPN label will be added at the same time.
Verify the BGP VPNv4 routing table to VRF 200:BBB.
Note: Route to the LocationC for BBB will automatically reflect since the routing protocol being implemented is BGP.
Let's verify also the labels being assigned to the VRF routes.
Notice a different 100.100.10.0/24 network label assignment on 100:AAA and on 200:BBB.
Checking on the forwarding table and the next-hop.
output shows that the routes are exported to the VPNv4. It also shows how to get to that network.
Now let's advertise the routes coming from BBB at location B by doing an import.
address-family ipv4 vrf 200:BBB autonomous-system 200 -> create ipv4 and specify 200:BBB to use AS 200 redistribute bgp 64500 metric 1 1 1 1 1 -> import routes from BGP into VRF with all metric value of 1.
Verify the routes from the BBB location C is being added to the BBB at location A.
Verify also the route from BBB at location A if is being added on the BBB at location C.
PE-LocationA is now configured for mutual redistribution on VRF 100:AAA and VRF 200:BBB.
Before we configure mutual redistribution on PE-LocationB router. Let's check first the routing on the CE at location B.
Objective:
AAALOCATIONB needs to have the external OSPF route from the AAALOCATIONA.
BBBLOCATIONB needs to have the external EIGRP route from the BBBLOCATIONA and BBBLOCATIONC.
Let's configure the export and import of the OSPF route on PE-LocationB.
Check the VRF 100:AAA BGP vpn topology and its corresponding label parameters.
Verify the forwarding table and next hop.
AAA on location A should have an External OSPF route reflecting the following:
100.90.1.0/30
100.90.10.0/24
100.90.100.100/32
Also you can see the VPN label: 2015.
Inter area OSPF on AAA Location B had formed with its corresponding VPN label: 1015.
Verify the BGP vpnv4 routing table and the label.
Check the forwarding table and the next hop going to 100.100.100.100/32.
No MPLS label assigned to the 100.90.0.0/16 since this is going via VPNv4.
Now let's configure the EIGRP on the BBB at Location B. Again, BBBLOCATIONB needs to have the external EIGRP route from the BBBLOCATIONA and BBBLOCATIONC.
Currently there is no external route coming from BBB at location B and BBB at location C.
Lets do the import and export of routes on the PE-LocationB.
Verify that the external EIGRP route from the BBB Location A and BBB Location C is reflected on BBB Location B.
Check the BGP vpnv4 routing topology including the assigned labels on the PE-LocationB. Output should include the BGP routes coming from BBB Location A and BBB Location C.
Verify the VPNv4 label assigned.
Verifying the next-hop address.
PE-LocationA and PE-LocationB is now configured for mutual redistribution.
On our PE-LocationC router, we just need to configure the RIP protocol since BGP has already been done advertising its route.
Let's configure the export and import.
Now let's compare the previous routing from AAA at Location C with its new routing after we perform the export and import of routes to VRF.
The route from AAA at location A and Location B is now learned by AAA at location C via RIP protocol.
We can check the MPLS path and verify the VPN label assigned to the loopback.
Check BGP vpnv4 topology from the PE-LocationC including the VPN labels on each route.
From AAA Location B, loopback on AAA at Location A and AAA at Location C should be reachable. while BBB at Location A and BBB at location C should be unreachable.
From BBB Location B, loopback on BBB at Location A and BBB at Location C should be reachable. while AAA at Location A and AAA at location C should be unreachable.
Now you have your route being distributed in an MPLS L3VPN environment with its corresponding VRF.