We have a number of branch offices connected in a hub-and-spoke configuration with frame-relay links. More recently we connected them with MPLS links, but due to cost considerations with our provider we kept the frame-relay links as backups (but with a zero CIR).
The issue now is which routes are preferred. We run EIGRP internally, but the MPLS connections use BGP. Once the BGP redistributes into EIGRP, the MPLS links are "EIGRP External", and the old frame-relay links are preferred. I worked around this for now by setting the admin distance of EIGRP external to be lower than the internal. We redistribute nothing else into EIGRP, so this does what I want. But my question is whether there is any risk in resetting the admin distances in this way. Should I be accomplishing this using route-maps an policies instead?
Yes, that simple.
Make sure to have remote-as 65000 on the new neighbor entry, remove EIGRP at the Branch office and the summary EIGRP piece at the Home Office.