Minh Huynh Prasant Mohapatra Stuart Goose Cross-over spanning trees Enhancing metro ethernet resilience and load balancing. 251-260 2007 BROADNETS http://dx.doi.org/10.1109/BROADNETS.2007.4550433 conf/broadnets/2007 db/conf/broadnets/broadnets2007.html#HuynhMG07