Giới thiệu về công nghệ SONET và SDH trong truyền dẫn quang
SONET Overview • SONET is a physical layer standard. • A synchronous frame structure for multiplexing digital traffic. • Frame structure: 9 rows of 90 columns of 8-bit bytes. • Bytes are transmitted one row at a time, from left to right • First three columns of STS-1 frame are for section overhead and line overhead • Remaining 87 columns are for the Synchronous Payload Envelope (SPE) STS-1 frame overheads STS-1 frame: section overhead 17.4 Section overhead is recalculated for each SONET device (regenerators and multiplexers). STS-1 frame: line overhead STS-1 frame: path overhead 17.7 Path overhead is only calculated for end-to-end (at STS multiplexers). SONET Structure SONET ARCHITECTURE • Path Layer: Mapping of DS0, DS1, DS3, FDDI to Payload • Line Layer: Frame synchronization and data multiplexing into a SONET frame • Section Layer: Framing, error monitoring and bit-scrambling • Photonic Layer: Fiber characteristics, encoding, transmitter and receiver types [...]...In a simple SONET linear network • PTE (path-terminating equipment) sits at each end, takes sub-rate signals and multiplexes them into a SONET frame • Between PTE devices are several LTE (line-terminating equipment) devices: an ADM (add/drop multiplexer) – Instead of de-multiplexing entire signal, as PTE does, it pulls out only subrate services it needs and inserts different signals... pulls out only subrate services it needs and inserts different signals • If network is long enough, STE (section-terminating equipment) will be in fiber These repeaters take incoming signal from one side and rebroadcast it out on other side – Placement of STE in the network depends on strength of signal being transmitted down the fiber Thank You . SONET Overview • SONET is a physical layer standard. • A synchronous frame structure for multiplexing digital traffic. • . synchronization and data multiplexing into a SONET frame • Section Layer: Framing, error monitoring and bit-scrambling • Photonic Layer: Fiber characteristics, encoding, transmitter and receiver. device (regenerators and multiplexers). STS-1 frame: line overhead STS-1 frame: path overhead 17.7 Path overhead is only calculated for end-to-end (at STS multiplexers). SONET Structure SONET ARCHITECTURE • Path