The tremendous usefulness of the modern Web results from ubiquitous, high-bandwidth access to the Internet. Required for this high-bandwidth access is a network underlayer providing long-distance, high-capacity data transport. This transport layer consists of IP switching equipment and dense-wave-division-multiplexing optical transport. The design of the transport layer is very complex, with simultaneous goals of minimizing capital investment, maximizing capacity, maximizing flexibility for future growth, and respecting design rules. I will overview IP-over-optical technology, illustrate design constraints, and describe the algorithms and tools used to design networks, all in the context of a specific Alcatel-Lucent data transport product.