18. Basic SONET signal STS = synchronous transport signal N byte-interleaved; OC-N = Optical carrier level N ; DS = Digital Signal. SONET Hierarchy 5,376 DS–1s or 192 DS–3s 9,953.280 STS–192, OC–192 1,344 DS–1s or 48 DS–3s 2,488.320 STS–48, OC–48 336 DS–1s or 12 DS–3s 622.080 STS–12, OC–12 84 DS–1s or 3 DS–3s 155.520 STS–3, OC–3 28 DS–1s or 1 DS–3 51.840 STS–1, OC–1 Capacity Bit Rate (Mbps) Signal

19. Basic SONET signal Nonsynchronous Hierarchy 28 DS–1s 44.736 DS–3 96 DS–0s 6.312 DS–2 24 DS–0s 1.544 DS–1 1 DS–0 0.064 DS–0 Channels Bit Rate (Mbps) Signal

25. SONET: STS–1 Building Block STS–1 Frame Format

26. SONET: STS–1 Building Block STS–1 Frame Elements

28. SONET: STS–1 Building Block