NX-OS changes how type 5 external routes work

NX-OS supports and rfc 2328 which says that if there are two paths to an ASBR one through area 0 and one that is not the NON AREA 0 is what is preferred. So when you move to nexus devices or add new routers, two type 5 external routes may not be put in as equal cost routes even though all the costs are equal. So you may need to add a non 0 area to your new router to get the load balancing you want. There are other factors to be considered in complex topologies see http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/117824-config-ospf-00.html