We will be using Kurose and Ross' excellent textbook Computer Networking: A Top-Down Approach. This text is different from many other network texts in its approach. By working from the top of the stack down, the student quickly gets familiar with many of the systems they use daily. This familiarity is then extended, layer-by-layer, from the application layer, to the transport layer, to the network layer, etc.
For the Fall 2016 semester, we will use the 6th edition. I am aware that the 7th edition was just published, and it has some substantial changes. However, during this first semester after publication, used copies will be very rare. By sticking to the 6th edition, you should be able to locate used copies at a much reduced price.
If you do wish to use the 7th edition, you are welcome to do so. You'll have to make a few adjustments to the sections I've assigned for reading, however.
I've also been asked if the International Edition is usable for the class. I don't know for certain, as I've not seen that edition. I imagine it would work. But, if you choose to use it, you do so at your own risk.