INE WorkBook LAB:4.12 MPLS L3 VPN and OSPF Domain-ID
this LAB is confusing me very much , I think there is something wrong with the lab description :
first lets check the required tasks for configuring OSPF as PE-CE routing protocol below :
Configure OSPF routing for the VRF as follows:
o Use Process-ID 100.
o Enable OSPF Area 0 between R1 & R2.
o Enable OSPF Area 0 between XR1 & XR2.
o Enable OSPF Area 120 between R1 & XR2.
o Advertise the Loopback0 network of R1 into OSPF Area 1.
o Advertise the Loopback0 network of XR2 into OSPF Area 20.
o Redistribute the Loopback1 networks of R1 and XR2 into OSPF.
o Modify the link between R1 and XR2 to have an OSPF cost of 100.
o Configure the OSPF Domain-ID on R2 and XR1 for the VRF aware process as
type 0005 with value 0x000000640200.
here is the topology , I Put the required points on the topology to be more clear
what is confusing me is in page 302 at the top of the page there is the below note :
When R1 and XR2 make their path selection decision, they now see two possible paths to
each other’s Loopback0 networks, one via the MPLS L3VPN PE and one via the backdoor link.
and as per my knowledge this is not true because R1 loopback 0 is in area 1 and XR-1 loopback 0 is in area 20 so for any traffic to pass between those to loopbacks it must use area 0 which in our case the route to the MPLS-VPN backbone not the backdoor link which is in area 120 that sounds more logic.
and to do more confirmation I increased the cost of the link between R1 and R2 to the ospf max cost and found that R1 still prefer that link , I also shut it down and the route to to XR1 loopback didn't show up in the routing table.
so did any one noticed that mistake???