Special Report: Next Generation Internet Applications
4.1 High-Speed Wide Area Networks Conservative estimates predict Internet traffic will double every six months for the next few years. By the end of 2002, the United States will need 35 Tbps of network capacity to support Internet traffic. At 35 Tbps, Internet traffic within the US alone will be ten times greater than all of the voice traffic in the world.
Every study predicts that data traffic will continue to grow faster than voice traffic. Predominant growth in IP-based traffic will drive new network development to a data-optimized architecture based on combinations of IP and ATM switching technology for the near term.[29][30] Photonic switching will eventually displace ATM and IP from high-speed core networks and will increase the capacity of core networks many times over current electronic switching technology.
Optical fibers and DWDM are proving to be ideal, cost-effective ways of addressing the rapid growth in data traffic. Today, DWDM systems are available that combine up to 40 OC-192 (10 Gbps per channel, 400 Gbps total) channels onto a single fiber. Near term systems will deliver 160 OC-768 (40 Gbps per channel, 6.4 Tbps total) channels per fiber, and laboratories are now demonstrating prototype systems capable of 320 OC-768 channels (12.8 Tbps total) per fiber.[31] Over time, electronics will improve to a point where OEO devices will be capable of driving an OC-768 channel economically.
4.1.1 Switching and Routing Within Photonic Networks Some network layer technologies are more readily adapted to interface with DWDM channels than others are. ATM standards and interface electronics already exist in forms capable of driving high capacity optical channels. For example, ATM technology readily supports automatic detection of network faults and restoration of traffic along alternate paths. ATM's interfaces map directly from the SONET optical channel structure to the DWDM optical structure provided the optical network contains the necessary wavelength conversion functions. The transition from ATM-over-SONET to ATM-over- DWDM is straightforward. The same statement cannot be said of IP standards and electronic interfaces.
There are problems integrating IP and DWDM directly. DWDM currently lacks the ability to automatically protect, restore, and groom IP traffic in ways that make efficient and reliable use of DWDM channels. SONET/SDH currently provides these functions within DWDM-based networks. However, the advent of OC-192 routers and ATM switches are making SONET multiplexers superfluous in many networks. There is a need to interface ATM switches and IP routers directly to the DWDM optical layer.
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