(Editor's note: This article is also included in FierceTelecom's new eBook called Packet Optical Networking Platforms: Maintaining the legacy, next-gen balance. Click here to get your free copy today.)
A few years ago, Verizon architects recognized that growing business services on its FiOS network, combined with the carrier's video-backhaul chores, called for a new network design. That design had to allow the carrier to scale its network to accommodate growing traffic volumes and reduce CAPEX and OPEX spending. Equally important, it had to support both TDM--and packet-based traffic as Verizon gradually migrated its network toward the Holy Grail of the telecom world--an all-IP infrastructure.
Glenn Wellbrock, director of optical transport network design and architecture, says the legacy Verizon network relied heavily on stacked SONET rings, which limited grooming, aggregation and switching to the interface rate. That architecture was inadequate for, among other things, backhauling video traffic between headends and serving offices. Verizon knew a ROADM network was the solution to transporting traffic between the headends and video serving offices--and the logical starting point for its overall TDM-to-packet migration strategy.
"By going with the ROADM, we knew that we'd have a lot of it out there, and we decided to put a backplane on it that would support connectivity to a centralized fabric," he explains. "It meant more money upfront, of course, but going forward, that [centralized fabric] can give us both traditional, SONET-type cross-connect functionality and also Ethernet or VLAN cross-connect functionality."