Ethan Banks has a great article @ PACKETattack: in Assembly Required – Interconnecting 2 Ethernet Chassis Switches he describes various options you have when you want to connect your redundant core switches. Using more than one physical link is the obvious choice; most people are careful enough to use at least two linecards, but the true magic begins when you start considering the bandwidth allocation to individual linecards and port groups within linecards.
Ivan Pepelnjak, CCIE#1354, is the chief technology advisor for NIL Data Communications. He has been designing and implementing large-scale data communications networks as well as teaching and writing books about advanced technologies since 1990. See his full profile, contact him or follow @ioshints on Twitter.