Application of Optical Ethernet Technology in IP MAN Optical Networks

   Optical Ethernettechnology is the convergence and evolution of two mainstream communication technologies: the integration of optical networks and Ethernet. It combines the advantages of both Ethernet and optical networks, such as the ubiquity, low cost, flexible networking, and simple management of Ethernet, and the high reliability and large capacity of optical networks. The high speed and large capacity of Optical Ethernet eliminate the bandwidth bottleneck between LANs and WANs, and it will become the single network architecture for the future convergence of voice, data, and video. Optical Ethernet technology is one of the mainstream technologies for building broadband metropolitan area optical networks.

1. Proposal of Optical Ethernet

  Today, both enterprises and carriers aim to reduce costs and increase revenue: (1) For enterprises, the e-commerce environment brings opportunities to meet customer demands and increase revenue. Enterprises can connect with customers, partners, and suppliers in real time through the network. However, although enterprise demand for network capacity continues to grow, investment in networks has not grown at the same pace. Enterprises want to obtain more services at lower costs to maximize savings; (2) For carriers, the primary consideration in current network construction is how to maximize profits while supporting existing services. Theaccess bandwidth bottleneck, rate mismatch, and multi-protocol conversion issues in the MAN make it difficult for carriers to provide the access rates required by enterprise users.

  The proposal of the Optical Ethernet concept addresses the above issues and brings revolutionary changes to the construction of broadband MANs. Current MANs are based on the SDH architecture. SDH was originally designed for low-speed, circuit-switched voice services, ensuring good QoS performance and providing 50ms circuit protection switching time; however, SDH equipment is expensive, inflexible, and inefficient for data services. Optical Ethernet, on the other hand, is based on the widely deployed and mature Ethernet technology, with enhanced network management and traffic engineering capabilities to meet the data rate and transmission distance requirements of MANs. Once carriers build optical metropolitan Ethernet networks, they can directly provide Ethernet ports at the backbone layer, enabling seamless connectivity with LANs.

2. Advantages of Optical Ethernet

   Ethernet technology was proposed by Xerox Corporation in 1970, initially allowing users to share 10Mbit/s bandwidth over coaxial cable. Later, Ethernet quickly evolved to run over unshielded twisted pair cabling, with switches providing users with dedicated 10Mbit/s connections. Today, switched Ethernet can deliver 100Mbit/s dedicated bandwidth to the desktop, and gigabit (Gbit/s) connectivity to users will soon be realized. Due to its speed, low cost, and ease of use, this "plug-and-play" technology has become the standard for over 90% of enterprise LANs.

Optical Ethernet can be applied in both private and public networks. It can be configured in point-to-point, mesh, or ring topologies, and can be deployed in LANs, MANs, and WANs. The advantages of applying Optical Ethernet technology include:

   (1) Elimination of bandwidth bottleneck: Optical Ethernet transmits end-to-end LAN services in its native format and speed, without protocol conversion or rate reduction, thereby breaking the bandwidth bottleneck between LANs and WANs.

   (2) High reliability: Optical Ethernet combines the proven robustness of Ethernet in LANs with the well-known advantages of optical fiber transmission in MANs and WANs, providing five-nines availability. Ethernet over RPR (EoRPR) can guarantee 50ms protection switching time in the event of catastrophic failures.

   (3) Strong security: Once a terminal user's Ethernet data frame enters the fiber Ethernet network, it is encapsulated to protect the transmitted data and isolated from other users' service data flows.

   (4) Good scalability: As traffic and bandwidth have increased, Ethernet technology standards have advanced to higher rates while maintaining compatibility with existing network architectures.

   (5) Low port cost: Since Ethernet is widely used in enterprise and campus networks, its hardware cost is very low and the technology is highly mature, significantly reducing carriers' network construction costs. For example, gigabit Ethernet ports cost only 1/4 of ATM and SDH ports, while the upcoming 10Gbit/s Ethernet ports will cost approximately 1/7 of SDH ports.

   (6) High network efficiency: Traditionaltelecom networks adopt complex multi-layer architectures (such as IP over ATM, IP over SONET, and IP over DWDM). The disadvantages of this architecture are: on one hand, ATM and SDH equipment is very expensive, increasing carrier costs; on the other hand, when data is transmitted between LANs and WANs, complex protocol conversion is required through routers, which increases network overhead, reduces transmission efficiency, and introduces latency and jitter. Optical Ethernet is end-to-end Ethernet, requiring no protocol conversion when data is transmitted between LANs and WANs, thereby greatly improving transmission efficiency.