Lab: iBGP and OSPF Traffic Engineering
Here’s the scenario: An enterprise network with an MPLS core and two branch locations connected to their own Provider Edge (PE) router. In addition to the MPLS link, the PEs are also connected via a DMVPN tunnel. The PEs are peering via iBGP (of course) and are also OSPF neighbors on the DMVPN. Both Customer Edge (CE) routers at the branch are OSPF neighbors with their local PE.
Task: Use the high speed MPLS network as the primary path between the CE routers and only use the DMVPN network if the MPLS network becomes unavailable.
Question: Is the solution as simple as adjusting the Admin Distance (AD) so that the iBGP routes are more preferred?
Default State
The obvious first issue is the default AD for iBGP (200) is higher than the default AD of OSPF (110) which means the OSPF path over the DMVPN is going to be preferred. This is confirmed if we do a traceroute from R5 to R6:
R5#traceroute 6.6.6.6 source lo5
1 10.0.45.4 2 msec 0 msec 1 msec
2 10.10.10.7 17 msec 17 msec 17 msec
3 10.0.67.6 18 Continue reading