Using BGP as the only Routing Protocol on the Corportate ...

So with our previous point-to-point setup we used EIGRP and pretty much a flat network.  Several of our sites had direct Internet connections and we used OpenVPN to create VPN tunnels between these sites for a "failover" network in the event of a primary link failure.  These routes, along with the "default" route to the Internet for that site, were injected into the network by a Linux box running Quagga with OSPF and a neighbor Cisco router the redistributed the routes between OSPF and BGP.  We also used the Linux box to monitor the local Internet connections.

This provided a great setup, if the Linux box detected that the local Internet connection was down, it would remove to default route, the router would know about default routes at other sites with higher metrics and the Internet would simply failover to using another sites connections.  If the primary WAN link failed, those routes would be gone from the router, and the router would use the OSPF injected routers from the OpenVPN tunnel.  Failover was reasonably quick (generally 30 seconds) and in a few cases sites ran for hours before they even noticed the primary link was down.

This became far more complicated when we switched to an MPLS WAN with BGP on the edge.  We decided to dump EIGRP as a proprietary protcol and use only OSPF on the LAN and BGP on the WAN edge.  Unfortunately, to achieve the desired failover results we needed to configure route redistribution between OSPF and BGP.  This was once again easy enough, but during failover event we kept running into issues of routing loops because of our network topology in the core.  We could easily use route tags to limit advertised routes, but as we fleshed out this configuration we started thinking that it seemed too complicated, there had to be an easier way.

After much thinking, reading, and discussion, we came to the conclusion that maybe the absolute best way to deal with this issue is to simply run BGP everywhere, LAN and WAN.  With BGP we could easily use the local preference attribute to prefer a given path, and there would be no issues with complex route redistribution.  In our head it seems crazy to run BGP in such a small network but, since we have to talk BGP with our WAN provider anyway, we though, why not?  It seems like this would provide the simplest solution.

Is anyone else running BGP only for their entire network?  We don't have any large, spread out campuses, generally a core which does all of the layer-3 routing, and an edge.  That's it.  I'll try to get some diagrams up soon.