You can change the reference bandwidth in Cisco IOS Software Release 11.2 and later using the ospf auto-cost reference-bandwidth command under router ospf. By default, reference bandwidth is 100 Mbps. The ospf link-cost is a 16-bit number. Therefo...
http://www.ebrahma.com/2013/10/changing-the-reference-bandwidth-modifying-the-cost-of-a-link-ospf/Labels: auto-cost-reference-bandwidth, bandwidth-interface-command-ip-ospf-cost-interface-command, Modifying-the-Cost-of-a-Link, Override-the-Default-Interface-Cost, Reference-Bandwidth, reference-bandwidth-for-faster-interfaces