Have a look at Radia Perlman's byzantine-robust protocl: PhD thesis "Network layer protocols with byzantine robustness", MIT, 1988, http://hdl.handle.net/1721.1/14403; and "Routing with Byzantine robustness", Sun tech report TR-2005-146, 2005. The latter is more a brief description with extensions on the original, but I don't have a URL to hand.