We encourage students and instructors to e-mail us with any comments they might have about our book. It’s been wonderful for us to hear from so many instructors and students from around the world about our first seven editions. We’ve incorporated many of these suggestions into later editions of the book. We also encourage instructors to send us new homework problems (and solutions) that would complement the current homework problems, or to send us ideas for interactively generated problems. We also encourage instructors and students to create new interactive animations that illustrate the concepts and protocols in this book. If you have an animation that you think would be appropriate for this text, please submit it to us. If the animation (including notation and terminology) is appropriate, we’ll be happy to include it on the text’s Web site, with an appropriate reference to the animation’s authors. We'd also love to hear from instructors about your ideas about how to most effective teach a computer networks course.

So, as the saying goes, “Keep those cards and letters coming!” Seriously, please do continue to send us interesting URLs, point out typos, disagree with any of our claims, and tell us what works and what doesn’t work. Tell us what you think should or shouldn’t be included in the next edition! Send your e-mail to kurose@cs.umass.edu and keithwross@nyu.edu.