Cox Communications has recently begun building out a national DWDM optical backbone which will run over a combination of owned and leased dark fiber spanning over 12,000 miles. While Cox could have leased transport capacity from a national carrier for this purpose, the build vs. leased capacity analysis showed the higher costs of leased transport would not be economical in the future. In the final analysis, the business case for building and operating this network was based primarily on the rapid growth of Cox’s cable modem data services alone. However, this network provides additional incremental economic benefits by allowing cost savings elsewhere in the network (e.g., by building consolidated national headends) and by enabling new revenue generating service opportunities not traditionally addressed by cable operators (e.g., a national footprint for commercial services or cell service backhaul). Two paramount design considerations for the network were total cost of ownership and service reliability. Other important considerations were network scalability, network flexibility, and the ability to rapidly turn up new bandwidth and services. To meet these requirements, Cox is implementing its national backbone with digital ROADMs (reconfigurable optical add/drop multiplexers).