1、Advances in Optical Networks: SONET,By Sean Goggin April 19, 2005,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,2,Overview,Fundamentals of Optical Networks SONET SDH Future of SONET,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,3,Fundamentals of Optical Networks,Fiber Opt
2、ic Medium Variants of Fiber and Optical Networks Multiplexing Methods Optical Network Equipment Topologies of Optical Networks,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,4,Fiber Optic Medium,Core Medium Where Light Travels Cladding Reflects Light Back into the Core Buffer Coating Pr
3、otective Coating,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,5,Variants of Fiber Optic,Single-Mode Small Core Approximately 9 Microns Uses IR Laser Light Transmitter Greater then 10 Miles* Most Expensive,Multi-Mode Large Core Approximately 62.5 Microns Uses Light Emitting Diode Trans
4、mitter Less then 10 Miles* Least Expensive *Without Regeneration,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,6,Types of Multiplexing,Time Division Multiplexing (TDM) Simplest Implementation Uses Single Wavelength Wavelength Division Multiplexing (WDM) Complex Implementation Multiple
5、Wavelengths on a Single Fiber to Increase Bandwidth,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,7,Types of Optical Networks,Opaque Weak Signals are Boosted with a Repeater Optical-Electronic-Optical (OEO) Repeater Incurs Pricey Conversion Delay,All-Optical (Pure) Weak Signals are Boo
6、sted with a Amplifier Erbium-Doped Fiber Amplifier (EDFA) Complete Photonic Boost,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,8,OEO Repeater,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,9,Erbium Doped Fiber Amplifier,Tuesday, April 19, 2005,Advances in Optical Networks
7、: SONET,10,Optical Network Equipment,Repeaters (OEO) & Amplifiers (EDFA) Optical Crossconnects (OXC) Photonic Switch with N Full-Duplex Ports Optical Add-Drop Multiplexer (OADM) Wavelengths Can Be Added and Removed from the Photonic Flow Ex: Remove Traffic for Inbound T1 and Traffic for Outbound T1
8、Needed for WDM,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,11,Optical Add-Drop Multiplexer,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,12,Topologies,Ring Topology Data Moves in One Direction around 1st Ring If Failure Occurs, Traffic is Rerouted in Opposite Direction
9、on 2nd Ring Each Ring is Total Capacity Self-Maintaining Mesh Topology Locations are Linked to 2 or More Other Locations If a Link Fails, Traffic is Rerouted around the Failure Requires Routes to be Established Before Failure,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,13,Ring Topolo
10、gy,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,14,Mesh Topology,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,15,Sample of Optical Network,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,16,Telecom Terminology,Synchronous Optical Network (SONET) Asynchronous
11、 Transfer Mode (ATM) Digital Signal (DS) Synchronous Transport Signal (STS) Optical Carrier (OC),Tuesday, April 19, 2005,Advances in Optical Networks: SONET,17,Telecom Circuits,Digital Signal Levels DS-0: 64 Kb Transmission Channel DS-1(T1): 1.5 Mb; Formed of 24 DS-0 DS-3(T3): 44.7 Mb; Formed of 672
12、 DS-0 Synchronous Transport Signals Channels STS-1: 52 Mb; Formed of 28 DS-0 or a Single DS-3 STS-3: 155 Mb; Formed of 84 DS-0 or 3 DS-1 Electric Signal is Converted to an Optical Signal it Becomes OC,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,18,SONET Connections,Tuesday, April 19,
13、 2005,Advances in Optical Networks: SONET,19,Background of SONET,Conceived by MCI During the Mid-1980s Designed from the Ground-Up to Hasten the Adoption of Optical Technology Capacity and Distance Increased Rapidly Due to Technological Developments Increased Purity of Fiber Optic Cable Longer Dista
14、nce without Regeneration Iron, Nickel, and Hydroxyl Ions Cause Impurities 1970s 20dB/km Loss, Today .2 dB/km Loss,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,20,Development of Laser Technology Lasers Yield Higher Energy then LEDs Allowing for Longer Distance Before Regeneration Devel
15、opment of Pure-Optical Technology Eliminating Optical-Electronic-Optical Conversion for Regeneration & Routing Increase Speed Possibility to Breach 10 Gb Barrier Wave Division Multiplexing & Dense Wave Division Multiplexing Using Multiple Wavelengths Capacity Can Be Increased Upwards of 92 Times the
16、 Capacity of a Single Wavelength,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,21,ANSI Transmission Standard United States Canada Korea Taiwan Hong Kong SDH used in Rest of the World Interoperable with SONET,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,22,Description,Phy
17、sical-Layer Standard Four-Layer Protocol Stack TDM Creates Synchronous Channels Multiplex Many Types of Traffic into Uniform Streams onto Fiber Optic Cabling Used Primarily as Backbone for ATM,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,23,Not Well Suited for Data Because of Native 6
18、4 kilobit “chunks” Utilizes Ring Topology for Reliability Low Maintenance do to Automatic Protection Switching (APS) Operations, Provisioning, Monitoring and Maintenance Functions are Done Uniformly and Efficiently,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,24,Typical SONET Ring is
19、Single Wavelength Opaque Network (Circa 2000) Entire Ring Must Operate at the Same Speed Adding Capacity to Rings Takes a Long Time and Typically Constitute a New Ring Due to Convenience Recent use of IP Over SONET,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,25,Four-Layers of SONET,P
20、hotonic: STS Electrical Data is Converted into OC Light Pulses and Vice Versa Section: Operates between Optical repeaters, Helping to Transmit STS Frames Line: Synchronizes and Multiplexes Multiple Streams into One Stream, Invokes APS When Required Path: Used for End-to-end Communications and Contro
21、l,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,26,STS-1 Frame,Section, Line, and Path Stack Layers are Overheard in the basic STS-1 Frame Frame is comprised of 9 Rows by 90 Columns = 810 bytes 1st 3 Columns of Each Row Addresses Section and Line Overhead (27-Bytes) 4th Column of Each
22、Row Addresses Path Overhead (9-Bytes) 86 Columns are Payload (774-Bytes),Tuesday, April 19, 2005,Advances in Optical Networks: SONET,27,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,28,Section Overhead,9-Bytes Supports Performance Monitoring (STS-N Signal) Local Orderwire Data Communic
23、ation Channels Framing,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,29,Line Overhead,18-Bytes Supports Locating the Payload in the Frame Multiplexing or Concatenating Signals Performance Monitoring Automatic Protection Switching (APS) Line Maintenance,Tuesday, April 19, 2005,Advances
24、in Optical Networks: SONET,30,Path Overhead,9 Evenly Distributed Path Overhead Bytes per 125 Microseconds Supports Performance Monitoring of Payload Signal Label Path Status Path Trace,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,31,SONET Virtual Tributaries,SONET is Capable of Accomm
25、odating Large and Small Capacities STS-1 Frame Payload Can be Sub-Divided to Create Virtual Tributaries (VT) Services Below DS3 are Transported via VTs in SONET VTs are Multiplexed to Reach Capacity of STS Payload,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,32,SONET Multiplexing Hier
26、archy,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,33,ATM Over SONET,Data-Link Layer Standard Voice Packets are Synchronous and Continuous, Data Packets are Asynchronous and Burst ATM Dynamically Allocates “Cells” to Voice and Data on Synchronous and Continuous Connection Provides Rou
27、ting, Quality of Service (QoS), and Flexible Traffic Engineering,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,34,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,35,ATM Cell,ATM Cell is 53-Bytes = 48-Bytes User Data + 5-Byte Header Fixed-Size Cell is More Manageable and Eas
28、y to Hardware Route Cell Header Contains Information Pertaining to the Cells Path, Priority, and Other Useful Information,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,36,ATM Cell Header,General Flow Control (GFC, 4-bit) Used for Local Functions, i.e. Identifying Multiple Stations that
29、 Share an ATM Interface. Typically not Used, Set to a Default Value Virtual Path Identifier (VPI, 8-bit) Used with the VCI, to Identify Next Destination of a Cell as it Passes through a Series of Routers on the Way to the Destination Virtual Channel Identifier (VCI, 16-bit) Used with the VPI, to Ide
30、ntify Next Destination of a Cell as it Passes through a Series of Routers on the Way to the Destination,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,37,Payload Type (PT, 3-bit) First Bit Indicates Whether the Cell Contains User or Control Data. If Cell Contains User Data, the Second B
31、it Indicates Congestion, and the Third Bit Indicates Whether the Cell is the Last in a Series of Cells Congestion Loss Priority (CLP, 1-bit) Indicates Whether the Cell Should be Discarded if it Encounters Extreme Congestion as it Moves through the Network Header Error Control (HEC, 8-bit) Checksum C
32、alculated Only on the Header Itself,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,38,ATM Header,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,39,Problems with ATM,“Cell Tax” 53-Byte ATM Cells are too Small for Most Data Traffic Ex: Requires Two 53-Byte ATM Cells to Transf
33、er the Smallest IP Data Packet (64-Bytes) 5-Byte Tax for Every 48-Bytes of Data for ATM vs. 1,500-Bytes with Minimal Overhead in Ethernet (Best Case) IP over ATM losses 20% of SONET Rate,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,40,IP Over SONET,Transports IP Utilizing Point-to-Poi
34、nt Protocol (PPP) and High-level Data Link Control (HDLC) PPP Provides Multi-Protocol Encapsulation, Error Control, and Link Initialization Control HDLC Frames the PPP-Encapsulated IP Datagrams into the STS-1 Frames Payload Requires STS-3c (3 Multiplexed STS-1),Tuesday, April 19, 2005,Advances in Op
35、tical Networks: SONET,41,Promising Future,WDM Allows ATM and IP to Coexist on SONET Pure-IP Networks Adopting Rapidly ISPs (AOL) Carriers (Sprint, GTE, Level 3, Qwest) Telephony Traffic Remains Static, IP Traffic Increasing 7% to 20% Per Month Cheaper then ATM,Tuesday, April 19, 2005,Advances in Opt
36、ical Networks: SONET,42,Issues to be Addressed,Generating Traffic for STS-3 (155 Mbps) PPP Establishes Direct Link No Addressing Capabilities No Routing Capabilities PPP has No Flow Control Additional Router Buffer Maybe Necessary Multiple Links Need to Be Provisioned in Event of Link Failure,Tuesda
37、y, April 19, 2005,Advances in Optical Networks: SONET,43,Without ATMs Layer-2 QoS, QoS Must be Added at Layer-3 Multi-Protocol Label Switching (MPLS) Utilized for QoS, Processor Intensive? HDLC Poor Scaling Hampers Connections Above OC-48 Lucent Proposes Simplified Data Link (SDL),Tuesday, April 19,
38、 2005,Advances in Optical Networks: SONET,44,SDH,Synchronous Digital Hierarchy (SDH) Published in 1989 by CCITT Addressing Synchronization of ANSI and CCITT Standards, Establishing a World Standard 32 64-kb Channels (E0) are Multiplexed into a 2 Mbps E1 Signal 21 E1 are Multiplexed into a STM-0 (52
39、Mbps),Tuesday, April 19, 2005,Advances in Optical Networks: SONET,45,SONET vs. SDH,1.5 Mbps DS1 vs. 2 Mbps E1 52 Mbps STS-1 vs. 155 Mbps STM-1 Multiplexing Smaller Connections into Larger is Similar to SONET SDH can Accommodate SONET By Changing SONET Signal from Bit-Interleaving to Byte-Interleavin
40、g.,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,46,SDH Connections,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,47,Connection Comparison,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,48,Future of SONET,10 Gb Barrier OC-768 Tunable Lasers SONET and Metro Ethernet Which is Best for MAN? IP Over SONET vs. IP Over Fiber Fiber Infrastructure without SONET,Tuesday, April 19, 2005,Advances in Optical Networks: SONET,49,
