sonet technology primer by martin schulman. slide 2 company confidential nanog, may 23-25 copyright...

SONET Technology SONET Technology PrimerPrimer

byby

Martin SchulmanMartin Schulman

NANOG, May 23-25Copyright © 1999, Juniper Networks, Inc.

Slide 2

COMPANY CONFIDENTIAL

Topics To Be CoveredTopics To Be Covered Motivation & Motivation &

HistoryHistory Termination Termination

Equipment And Equipment And Frame FormatsFrame Formats

Electrical And Electrical And Optical EncodingOptical Encoding

Topologies And Topologies And RedundancyRedundancy

PPP Over SONETPPP Over SONET Relationship To Relationship To

Other StandardsOther Standards


Slide 3


<1984 NA Digital <1984 NA Digital TelephonyTelephony

Key System Aspects:Key System Aspects:• M13 Building BlocksM13 Building Blocks• Asynchronous Asynchronous OperationOperation• Electrical DS3 SignalsElectrical DS3 Signals• Proprietary Fiber Proprietary Fiber Systems Systems • Brute Force Cross Brute Force Cross ConnectConnect• AT&T Network/Western AT&T Network/Western Electric EquipmentElectric Equipment

CentralCentralOfficeOffice



FiberFiber

Fiber OpticFiber OpticTransmissionTransmission

SystemsSystems• SwitchesSwitches• Leased LineLeased Line

M13M13 M13M13

DS3DS3

DS1DS1

DS3DS3

DS1 CrossDS1 CrossConnectConnect

M13M13

DS1DS1

DS1DS1

No GuaranteedNo GuaranteedTimingTiming

SynchronizationSynchronization


Slide 4


Post-Divestiture Post-Divestiture DilemmasDilemmas

Faster Fiber Coming:Faster Fiber Coming:• Need “Mid-Span Need “Mid-Span Meet”Meet”• Support New ServicesSupport New Services• Allow Other Allow Other TopologiesTopologies• Standardize Standardize RedundancyRedundancy• Common OAM&PCommon OAM&P• Scalable Cross Scalable Cross ConnectConnect

DifferentDifferentCarriers,Carriers,VendorsVendors

• SwitchesSwitches• Leased LineLeased Line• LAN ServicesLAN Services• Data ServicesData Services

M13M13

SupportSupportOtherOther

Topologies,Topologies,Protect FibersProtect Fibers

DS1DS1

InternalInternalDS3 CrossDS3 CrossConnectConnect


Slide 5


The Standards ProcessThe Standards Process

19841984 19851985 19861986 19871987 19881988

SONET/SDHSONET/SDHStandardsStandardsApprovedApproved

ANSI ApprovesANSI ApprovesSYNTRANSYNTRAN

DivestitureDivestiture

Exchange CarriersExchange CarriersStandards Associate (ECSA)Standards Associate (ECSA)T1 Committee FormedT1 Committee Formed

ANSI T1X1ANSI T1X1ApprovesApprovesProjectProject

Bellcore ProposedBellcore ProposedSONET PrinciplesSONET PrinciplesTo ANSI T1X1To ANSI T1X1

CCITT ExpressesCCITT ExpressesInternet in SONETInternet in SONET

British and JapaneseBritish and JapaneseParticipation in T1X1Participation in T1X1

CCITT XVIIICCITT XVIIIBegins StudyBegins StudyGroupGroup

CEPT ProposesCEPT ProposesMerged ANSI/CCITTMerged ANSI/CCITT

StandardStandard

US T1X1 AcceptsUS T1X1 AcceptsModificationsModifications

Standard That Almost Wasn’tStandard That Almost Wasn’t• >400 Technical Proposals>400 Technical Proposals• Rate Discussions AT&T vs. Rate Discussions AT&T vs. BellcoreBellcore• International Changes For International Changes For Byte/Bit Interleaving, Frames, Byte/Bit Interleaving, Frames, Data RatesData Rates• Phase I, II, III Separate APS, etc.Phase I, II, III Separate APS, etc.

SONET Concept Developed By BellcoreSONET Concept Developed By Bellcore


Slide 6


SONET DefinedSONET Defined

Synchronous Optical NetworkSynchronous Optical Network Set of Layer 1 Standards For Set of Layer 1 Standards For

Communication over Fiber Optic (and Communication over Fiber Optic (and Electrical) Links In Order To Facilitate:Electrical) Links In Order To Facilitate: Fiber Optic Link Speed IncreasesFiber Optic Link Speed Increases Variety Of Topologies and Grooming Variety Of Topologies and Grooming

FunctionsFunctions Operations, Administration, Maintenance, Operations, Administration, Maintenance,

and Provisioning (OAM&P)and Provisioning (OAM&P) When Used As Telephony Carrier When Used As Telephony Carrier

Equipment And CPE InterconnectEquipment And CPE Interconnect


Slide 7


Equipment TypesEquipment Types

PTEPTE

All Perform Electro-All Perform Electro-OpticalOpticalConversionConversion• Section Termination Section Termination (STE)(STE)• Line Termination (LTE)Line Termination (LTE)• Path Termination Path Termination (PTE)(PTE)Data Between PTE May Data Between PTE May Traverse Multiple LTE, Traverse Multiple LTE, STESTE

LineLineSONET EndSONET EndDevice - I.e.Device - I.e.TelephonyTelephonySwitch, RouterSwitch, Router

PathPath

SectionsSections

RepeatersRepeaters

PTEPTE


Slide 8


STS-1 Frame FormatSTS-1 Frame Format90 Bytes90 Bytes

Or “Columns”Or “Columns”

99RowsRows

Each Small RectangleEach Small RectangleRepresents One ByteRepresents One Byte

Transmitted MSB FirstTransmitted MSB FirstFrame TransmissionFrame Transmission• Top Row First, Sent Left To Top Row First, Sent Left To RightRight• 125 125 s/Frames/Frame• 810 Bytes/Frame810 Bytes/Frame• 51.84 Mbps Rate51.84 Mbps Rate• Frame Contains One PayloadFrame Contains One Payload


Slide 9


Section Overhead (SOH)Section Overhead (SOH)

A1A1=0xF6=0xF6

A2A2=0x28=0x28

J0/Z0J0/Z0STS-IDSTS-ID

B1B1BIP-8BIP-8

E1E1OrderwireOrderwire

F1F1UserUser

D1D1Data ComData Com



Section OverheadSection Overhead• 9 Bytes Total9 Bytes Total• Originated And Terminated Originated And Terminated By All Section Devices By All Section Devices (Regenerators, Multiplexers, (Regenerators, Multiplexers, CPE)CPE)• Other Fields Pass UnaffectedOther Fields Pass Unaffected

RcvRcvSOHSOH

• A1,A2 - Framing BytesA1,A2 - Framing Bytes• J0/Z0 - Section ID, J0/Z0 - Section ID, ReservedReserved• BIP-8 - Bit Interleaved BIP-8 - Bit Interleaved ParityParity• E1 Orderwire - Craft E1 Orderwire - Craft Voice Interface Between Voice Interface Between SectionsSections• F1 User - Proprietary F1 User - Proprietary ManagementManagement• D1-D3 - 192 Kbps D1-D3 - 192 Kbps OSI/CMIP ChannelOSI/CMIP Channel

XmtXmtSOHSOH


Slide 10


Line Overhead (LOH)Line Overhead (LOH)H1H1

PointerPointerH2H2

PointerPointerH3H3

Pointer ActPointer Act

B2B2BIP-8BIP-8

K1K1APSAPS

K2K2APSAPS




Line OverheadLine Overhead• 18 Bytes Total18 Bytes Total• Originated And Terminated Originated And Terminated By All Section Devices By All Section Devices (Regenerators, Multiplexers, (Regenerators, Multiplexers, CPE)CPE)• LOH+SOH=TOH (Transport LOH+SOH=TOH (Transport OH)OH)

• H1-3 - Payload PointersH1-3 - Payload Pointers• BIP-9 Bit ParityBIP-9 Bit Parity• K1, K2 - Automatic K1, K2 - Automatic Protection SwitchingProtection Switching• D4-D12 - 576 kbps D4-D12 - 576 kbps OSI/CMIPOSI/CMIP• S1 - Time Sync IndicatorS1 - Time Sync Indicator• M0 - Return Error M0 - Return Error IndicatorIndicator• E1 Orderwire - Craft Voice E1 Orderwire - Craft Voice Interface Between SectionsInterface Between Sections







S1S1SyncSync

M0M0REIREI

E1E1OrderwireOrderwire

RcvRcvSOHSOH

XmtXmtSOHSOH

XmXmtt

SOSOHH

XmXmtt

LOLOHH

RcvRcvSOHSOH

RcvRcvLOHLOH


Slide 11


Path Overhead (POH)Path Overhead (POH)J1J1

TraceTrace

B3B3BIP-8BIP-8

C2C2Sig LabelSig Label

Path OverheadPath Overhead• H1,H2 Point To Beginning - H1,H2 Point To Beginning - Beginning Floats Within FrameBeginning Floats Within Frame• 9 Bytes (1 Column) Spans 9 Bytes (1 Column) Spans FramesFrames• Originated And Terminated By Originated And Terminated By All Path Devices (I.e. CPE, All Path Devices (I.e. CPE, Switches)Switches)• STE Can Relocate PayloadSTE Can Relocate Payload

• J1- J1- Repeated ID Repeated ID StringString• BIP-8 - BIP-8 - ParityParity• C2 - Payload C2 - Payload Type Type IndicatorIndicator• G1 - End G1 - End End Path End Path StatusStatus• F2 - UserF2 - User• H4 - Use H4 - Use Depends On Depends On PayloadPayload• Z3-5 - Z3-5 - Future Future GrowthGrowth

G1G1Path StatPath Stat

F2F2UserUser

H4H4IndicatorIndicator

PTEPTE

Z3Z3GrowthGrowth

Z4Z4GrowthGrowth

Z5Z5TandemTandem

PTEPTESTESTE

Frame NFrame N

Frame N+1Frame N+1Frame NFrame N

Frame N+1Frame N+1


Slide 12


SPESPE

Synchronous Payload EnvelopeSynchronous Payload Envelope• Contains POH + DataContains POH + Data• First Byte Follows First Byte Of First Byte Follows First Byte Of POHPOH• Wraps In Subsequent ColumnsWraps In Subsequent Columns• May Span FramesMay Span Frames• Up To Single 49.536 Data Signal Up To Single 49.536 Data Signal - Enough for DS3- Enough for DS3

Defined PayloadsDefined Payloads• Virtual Tributaries Virtual Tributaries (For DS1, DS2)(For DS1, DS2)• DS3DS3• SMDSSMDS• ATMATM• PPPPPP• More...More...


Slide 13


Accommodating JitterAccommodating Jitter

Positive Stuff Positive Stuff Negative Stuff Negative Stuff

Byte After H3 Ignored, Or H3 Holds Extra Byte To Byte After H3 Ignored, Or H3 Holds Extra Byte To Shorten/Lengthen FrameShorten/Lengthen FrameH1, H2 Values Indicate Changes - Maximum Every 4 FramesH1, H2 Values Indicate Changes - Maximum Every 4 FramesRequires Close (Not Exact) Clock Synchronization Among ElementsRequires Close (Not Exact) Clock Synchronization Among Elements


Slide 14


Clock SynchronizationClock Synchronization

Building Integrated Timing Building Integrated Timing SystemSystem• Hierarchical Clocking Hierarchical Clocking DistributionDistribution• Normally All Synch’d To Stratum Normally All Synch’d To Stratum 1 (Can Be Cesium/Rubidium Clock)1 (Can Be Cesium/Rubidium Clock)• Dedicated Link Or RecoveredDedicated Link Or Recovered• Fallback To Higher Stratum In Fallback To Higher Stratum In Failure (Temperature Controlled Failure (Temperature Controlled Crystal)Crystal)

PTEPTE

PTEPTE

BITSBITS BITSBITS

BITSBITS

PrimaryPrimaryReferenceReference

BackupBackupReferenceReference

•Level 1: 10Level 1: 10-11-11

•Level 2: 1.6x10Level 2: 1.6x10-8-8

•Level 3: 4.6x10Level 3: 4.6x10-6-6

•Level 4: 32x10Level 4: 32x10-6-6


Slide 15


STS-N Frame FormatSTS-N Frame Format

Composite FramesComposite Frames• Byte Interleave STS-1’sByte Interleave STS-1’s• Clock Rate = Nx51.84 MbpsClock Rate = Nx51.84 Mbps

90xN Bytes90xN BytesOr “Columns”Or “Columns”

N Individual STS-1 FramesN Individual STS-1 Frames

Examples Examples STS-1STS-1 51.84 Mbps51.84 MbpsSTS-3STS-3 155.520 Mbps155.520 MbpsSTS-12STS-12 622.080 Mbps622.080 MbpsSTS-48STS-48 2.48832 Gbps2.48832 GbpsSTS-191STS-191 9.95323 Gbps9.95323 Gbps


Slide 16


STS-Nc Frame FormatSTS-Nc Frame Format

Composite FramesComposite Frames• Same TOH Structure And Same TOH Structure And Data Rates As STS-NData Rates As STS-N• Not All TOH Bytes UsedNot All TOH Bytes Used• First H1, H2 Point To POHFirst H1, H2 Point To POH• Single Payload In Rest Of Single Payload In Rest Of SPESPE• Accommodates FDDI, E4, Accommodates FDDI, E4, etc.etc.

90xN Bytes90xN BytesOr “Columns”Or “Columns”

Examples Examples Only 1 BIP-8 for section layer (B1)Only 1 BIP-8 for section layer (B1)Only One DCC (D1-D3)Only One DCC (D1-D3)Only Two E1, E2 OrderwiresOnly Two E1, E2 OrderwiresOnly One User (F1)Only One User (F1)Only One APS (K1 and K2)Only One APS (K1 and K2)Only One DCC (D4-D12)Only One DCC (D4-D12)

TransportTransportOverheadOverhead


Slide 17


Transmission EncodingTransmission Encoding

OC-N Is Optical Carrier STS-OC-N Is Optical Carrier STS-NNLong Reach: 40 kmLong Reach: 40 km

1310 or 1550 nm SM1310 or 1550 nm SMIntermediate Reach: 15 kmIntermediate Reach: 15 km

1310 or 1550 nm SM1310 or 1550 nm SMShort Reach:Long Reach 2 Short Reach:Long Reach 2 kmkm

1310 nm MM1310 nm MM

E OE O

Electrical Transmission StandardElectrical Transmission Standard• STS-1: B3ZS (BPV), 450’STS-1: B3ZS (BPV), 450’• STS-3: Coded Mark Inversion, 225’STS-3: Coded Mark Inversion, 225’• Useful Intra-Office ConnectionUseful Intra-Office Connection

1+x1+x66+x+x77

ScramblingScrambling• Ensures Ones DensityEnsures Ones Density• Does Not Include A1, A2, C1 BytesDoes Not Include A1, A2, C1 Bytes• Output Is NRZ EncodedOutput Is NRZ Encoded


Slide 18


Network ElementsNetwork Elements

Nonstandard, Functional Nonstandard, Functional NamesNamesTM: Terminal MuxTM: Terminal MuxADM: Add-Drop MuxADM: Add-Drop MuxDCC: Digital Cross ConnectDCC: Digital Cross Connect (Wideband and (Wideband and Broadband)Broadband)MN: Matched NodeMN: Matched NodeD+R: Drop and RepeatD+R: Drop and Repeat

ADMADMTMTMDS1sDS1s

DS1sDS1s

MNMN MNMN

MNMNDCCDCC

D+RD+R

D+RD+R

D+RD+RMNMN


Slide 19


Topology Building BlocksTopology Building Blocks

DCCDCC

ADMADM

ADMADM

ADMADM

DCCDCC

ADMADM

ADMADM

ADMADM 2 Fiber Ring2 Fiber RingEach Line IsEach Line IsFull DuplexFull Duplex

DCCDCC

ADMADM

ADMADM

ADMADM 4 Fiber Ring4 Fiber RingEach Line IsEach Line IsFull DuplexFull Duplex

DCCDCC

ADMADM

ADMADM

ADMADM

Uni- vs. Bi-Uni- vs. Bi-DirectionalDirectionalAll Traffic Runs All Traffic Runs Clockwise, vs Either Clockwise, vs Either WayWay


Slide 20


OAM&POAM&P

Manageability Is RequiredManageability Is RequiredWell Defined Protocols, Alarms:Well Defined Protocols, Alarms:•Loss of Signal: All 0’sLoss of Signal: All 0’s•Loss Of Frame: Cannot Find A1,A2Loss Of Frame: Cannot Find A1,A2•Alarm Indication Signal - Line: Alarm Indication Signal - Line: Remote Side Sees LOS or LOFRemote Side Sees LOS or LOF•Remote Defect Indication - Line: Remote Defect Indication - Line: Remote Seeing Above AlarmsRemote Seeing Above Alarms•Alarm Indication Signal - Path: Alarm Indication Signal - Path: Indication To Downstream Devices Indication To Downstream Devices Of A ProblemOf A Problem•Remote Defect Indication - Path: Remote Defect Indication - Path: Indication To Upstream Devices Of Indication To Upstream Devices Of A ProblemA Problem

SONET Processing HardwareSONET Processing Hardware

OSI NodeOSI Node

HardwareHardwareError DetectionError Detection

HardwareHardwareError SignalingError Signaling

DCC LinksDCC Links


Slide 21


APSAPS

ADMADM

Line Protection SwitchingLine Protection SwitchingUses TOHUses TOHTrunk ApplicationTrunk ApplicationBackup Capacity Is IdleBackup Capacity Is IdleSupports 1:n, N=1-14Supports 1:n, N=1-14

Automatic Protection SwitchingAutomatic Protection Switching• Line Or Path BasedLine Or Path Based• Revertive vs. Non-RevertiveRevertive vs. Non-Revertive• Mechanism For Intentional Mechanism For Intentional CutoverCutover• Restoration Times ~ 50 msRestoration Times ~ 50 ms• K1, K2 Bytes Signal ChangeK1, K2 Bytes Signal Change• Common Uses: 2 Fiber UPSR or Common Uses: 2 Fiber UPSR or ULSR, 4 Fiber BPSRULSR, 4 Fiber BPSR

ADMADMADMADM ADMADM

Path Protection SwitchingPath Protection SwitchingUses POHUses POHAccess Line ApplicationsAccess Line ApplicationsDuplicate Traffic Sent On ProtectDuplicate Traffic Sent On Protect1+11+1

ADMADMADMADM


Slide 22


Packet Over SONET (POS)Packet Over SONET (POS)

PPPPPP ByteByteStuffStuffFCSFCS ScramblingScrambling SONETSONET

FramingFraming

Standard PPP EncapsulationStandard PPP Encapsulation• Magic Number RecommendedMagic Number Recommended• No Addres and Control CompressionNo Addres and Control Compression• No Protocol Field CompressionNo Protocol Field Compression

Standard CRC ComputationStandard CRC Computation• OC3 May Use CRC-16OC3 May Use CRC-16• Other Speeds Use CRC-32Other Speeds Use CRC-32

Special Data ScramblerSpecial Data Scrambler• 1+ x43 Polynomial1+ x43 Polynomial• Protects Against Transmitted Frames Protects Against Transmitted Frames Containing Synch Bytes Or Insufficient Containing Synch Bytes Or Insufficient Ones DensityOnes Density

SONET FramingSONET Framing• OC3, OC12, OC48, OC192 DefinedOC3, OC12, OC48, OC192 Defined• C2 Byte = 0x16 With ScramblingC2 Byte = 0x16 With Scrambling• C2 Byte = oxCF Without (OC-3)C2 Byte = oxCF Without (OC-3)


Slide 23


Technology RelationshipsTechnology Relationships

Synchronous Digital Hierarchy (SDH)Synchronous Digital Hierarchy (SDH) International Diffs - Terms, OH FieldsInternational Diffs - Terms, OH Fields Rates: STS-N -> STM-N/3 For N>=3Rates: STS-N -> STM-N/3 For N>=3

SDL ProposalSDL Proposal Fix HDLC For High Speed UseFix HDLC For High Speed Use Pt-Pt Links Without SONET OverheadPt-Pt Links Without SONET Overhead

WDM/DWDM:WDM/DWDM: More Capacity - Optical Routing For More Capacity - Optical Routing For

RedundancyRedundancy No Access To Lower-Level (I.e. DS1 No Access To Lower-Level (I.e. DS1

Signals)Signals)


Slide 24


AcronymsAcronyms ADM: Add-Drop MultiplexADM: Add-Drop Multiplex APS: Automatic Protection SwitchingAPS: Automatic Protection Switching BIP: Bit Interleaved ParityBIP: Bit Interleaved Parity BITS: Building Integrated Timing SupplyBITS: Building Integrated Timing Supply OC: Optical CarrierOC: Optical Carrier POH: Path OverheadPOH: Path Overhead POS: Packet Over SONETPOS: Packet Over SONET PTE: Path Terminating EntityPTE: Path Terminating Entity SDH: Synchronous Digital HierarchySDH: Synchronous Digital Hierarchy SONET: Synchronous Optical NetworkSONET: Synchronous Optical Network SPE: Synchronous Payload EnvelopeSPE: Synchronous Payload Envelope STE: Section Terminating EntitySTE: Section Terminating Entity STM: Synchronous Transport Module STM: Synchronous Transport Module STS: Synchronous Transport SignalSTS: Synchronous Transport Signal TOH: Transport OverheadTOH: Transport Overhead VT: Virtual TributaryVT: Virtual Tributary


Slide 25


ReferencesReferences

Telcordia (Bellcore) GR-253-CORETelcordia (Bellcore) GR-253-CORE ANSI T1.105 and T1.106ANSI T1.105 and T1.106 ITU-T G.707 and G.783ITU-T G.707 and G.783 SONETSONET, Walter J. Goralski, McGraw-, Walter J. Goralski, McGraw-

Hill Series on Computer Hill Series on Computer CommunicationsCommunications

RFC-1619 and SuccessorRFC-1619 and Successor http://search.ietf.org/internet-drafts/draft-ietf-pppext-http://search.ietf.org/internet-drafts/draft-ietf-pppext-

pppoversonet-update-04.txtpppoversonet-update-04.txt

http://www.juniper.nethttp://www.juniper.net

sonet technology primer by martin schulman. slide 2 company confidential nanog, may 23-25 copyright...

Documents

bellcore slide

company confidential

juniper networks

cpe interconnect slide

redundancy topologies

sonet ppp

sonet relationship

martin schulman slide