t mesh technologies that are being deployed. CONVERGENCE IN CORE AND METROPOLITAN NETWORKS In a telephone interview, Dave Parks, director of Product Marketing for Ciena Corpo- ration, made the following comment: Convergence in Core and Metropolitan Networks Carriers are investing in a new breed of networks that are all about IP packets on optical cabling. But carriers are not going to throw away their investments in SONET equipment. OTN transport and switching equipment gives them a way to accommodate SONET while migrating customers away from legacy services to higher-capacity Carrier Gigabit Ethernet services of up to 100Gbps. Optical Transport Network (OTN) is an International Telecommunications Union (ITU) standard for transmitting, monitoring, and managing traffic on fiber-optic cabling. It is used for asynchronous protocols such as Gigabit Ethernet as well as syn- chronous protocols such as Synchronous Optical Network (SONET), T1/E1, and T3/ E3. In asynchronous protocols, traffic is sent at irregular intervals, not at specific inter- vals. This contrasts with synchronous protocols where bits are sent at evenly spaced, regular intervals according to an internal timing source. The OTN standard provides a framework for transmitting both types of traffic. The OTN standard was created for the efficient operation of providers' multi- protocol metropolitan and global networks using interoperable equipment. The stan- dard provides a framework for programming, monitoring, and installing the growing amounts of IP packet traffic while preserving its capability to carry legacy traffic on optical networks. It does SO by specifying the encapsulation of legacy SONET/Syn- chronous Digital Hierarchy (SDH) traffic into OTN frames and its overhead informa- tion for addressing and billing. OTN-compliant equipment has the capability to transmit, program, and monitor various protocols, and assign Gigabit Ethernet or SONET/SDH to ports on the same line card via software. Thus, as the amount of SONET traffic decreases, port assign-