ars. 1,000 WDM + TDM 2.5 Gbps Ethernet the increase in aggregate capacity over the years of TDM (SONET/SDH) and TDM+WDM systems as well as the increase in Ethernet speeds. 1.4.1 SONET and Next-Generation SONET Positioning SONET/SDH is a standard (the former from ANSI and the latter from ITU) intended to support the interworking of optical equipment at various speeds, typically 2.5 Gbps, 10 Gbps, and in the near future 40 Gbps (lower speeds are also supportable). Interworking is achieved by defining a set of optical parameters, data-framing formats (the frame format for the basic building block in shown in Figure 1-15), clocking speeds, and OAM&P mechanisms. Figure 1-16 depicts the basic SONET arrangement, whereas Figure 1-17 illustrates the point-to-point environment of a SONET link. In the past few years, manufacturers and vendors of IP-based equipment have claimed that the inefficiencies of TDM-based technology could not accommodate the growth of Internet and data traffic. They suggested that Advances and Opportunities in Next-Generation SONET BIP-8/B1: Parity Checking Figure 1-15 Section Trace/Growth SONET's path, line, and section. JO/ZO 87 Columns of Payload STS-1 Synchronous Payload Envelope (STS-1 SPE) BIP-8/B2: Error Monitoring MO/M1 1310 nm Figure 1-16 1550 nm SONET environment (WDM Standards STS Electrical and drivers. Emerging) Signal SONET/SDH STS Electrical Optical EQUIPMENT Signal Signal (Based on TDM) Fiber STS Electrical Plant Signal Interfaces (1) Short Reach (2) Intermediate Reach (3) Long Reach Standards based: Allows multivendor interworking Leveraged emerging fiber-optic transport technologies Synchronous transmission: Addresses timing variations Reduces complexity of operations: Automation of OAM&P Network scalability: Enables multiplexing of lower-speed streams onto single high-speed transport Chapter 1 Figure 1-17 Path(s) SONET Path, Line, and Section Section Section Terminating Terminating Equipment Terminating Regenerator Terminating Equipment (PTE) Equipment (STE) Equipment (PTE) (PTE) 