shape peak <CIR> <Bc> <Be>
maximum burst rate = shape peak rate
http://blog.ine.com/2008/08/26/understanding-the-shape-peak-command/
http://brbccie.blogspot.jp/2012/12/a-different-perspective-on-cir-pir-tc_1785.html
http://www.techexams.net/forums/ccie/46786-shape-peak-vs-shape-average.html
http://www.flashcardmachine.com/ccie-traffic-shaping.html