I am taking a Telecommunications and Networking class.

I am taking a Telecommunications and Networking class. I am being asked to "Create a rough design for a private line network that would bring a 256 kbps private line to each of the bank’s fifty branch offices. Be economical, but ensure that there is redundancy in interisland connections. Assume that connections within an island do not need redundancy because of the high traditional reliability of private lines. " for First Bank of Paradise in Raymond Panko's "Business Data Networks and Telecommunications" What is a "rough design"?