76 8600 50114i 8600 smart routers synchronization configuration guide

Date Description of Changes76.8600-50114I 12.05.2015 Added 8665 Smart Router synchronization functionality in: • 2.1 Equipment Clock • 2.1.1 Equipment Clock Architecture • 2.2 Reference

Synchronization Configuration Guide

76.8600-50114I 12.05.2015

Revision History Document No Date Description of Changes

76.8600-50114I 12.05.2015 Added 8665 Smart Router synchronization functionality in:

• 2.1 Equipment Clock

• 2.1.1 Equipment Clock Architecture

• 2.2 Reference Clock Inputs

• 2.3 Station Clock Ports

• 2.4 Synchronous Ethernet Interfaces

• 3 Packet Frequency Synchronization

• 4 Phase/Time SynchronizationChanges or/and updates applied in: 2.3 Station ClockPorts,2.4 Synchronous Ethernet Interfaces,4 Phase/TimeSynchronization,5 Packet Phase/Time Synchronizationand

8 Frequency Synchronization Configuration Examples.Reworked2.1 Equipment Clockand2.2 Reference Clock InputsAdded the following:

• 4.1.1 8600 NEs Time Model

• 4.2.4 PTP Profiles for Phase/Time

• 5.2.4 Phase/Time Distribution (L3 Applications)

• 6.4 PTP Monitoring Capabilities

• 11.3 Phase/Time L3 Applications

• ToD Frame and Messages

• 4.2.3 PTP Fallbackand11.4 PTP Fallback Configuration76.8600-50114H 04.11.2014 Added 8602-D and 8615 Smart Router synchronization

functionality in:

• 2.1.1 Equipment Clock Architecture

• 2.2 Reference Clock Inputs

• 2.3 Station Clock Ports

• 2.4 Synchronous Ethernet Interfaces

• 3 Packet Frequency Synchronization

• 4 Phase/Time SynchronizationAdded1.1 Synchronization Terminology.Updates applied in1.4 Packet Synchronization Overview.Changes (node clock => equipment clock) applied in2.1 Equipment Clock

Reworked2.4 Synchronous Ethernet Interfacesand added support

of SyncE electrical SFP

Changes applied in3.1 8600 NEs Functionality.Changes (node time => time clock) applied in4.2 Time Clock.Added support in IFC2 line card (with 8x100/1000BASE-Xand 8x10/100/1000BASE-TX R2 IFMs) of L2 PTP slave andmaster in3.1 8600 NEs Functionalityand T-BC in4 Phase/TimeSynchronization

Updates applied in11 Phase/Time Synchronization ConfigurationExamples

The functionality described in this document for 8615 Smart Router is also applicable to 8615 Smart Router stacked, unless otherwise stated.

© 2015 Coriant All rights reserved.

This manual is protected by U.S and international copyright laws, conventions and treaties Your right to use this manual is subject to limitations and restrictions imposed by applicable licenses and copyright laws Unauthorized reproduction, modification,

distribution, display or other use of this manual may result in criminal and civil penalties.

The specifications and information regarding the products in this manual are subject to change without notice All statements, information, and recommendations in this manual are believed to be accurate but are presented without warranty of any kind,

express or implied Users must take full responsibility for their application of any products.

Adobe ® Reader ® are registered trademarks of Adobe Systems Incorporated in the United States and/or other countries.

Terms and Abbreviations Term Explanation

1PPS One Pulse Per SecondACR Adaptive Clock Recovery or Adaptive TimingADSL Asymmetric Digital Subscriber Line

AJB Adaptive Jitter BufferAMT Acceptable Master TableAPTS Assisted Partial Timing SupportATM Asynchronous Transfer Mode

BITS Building Integrated Timing SystemsBMCA Best Master Clock AlgorithmBTS 2G Base Station

CDC Control and DC Power Card There are two types of CDC: CDC1 and CDC2CES Circuit Emulation Service

CESoPSN Circuit Emulation Service over Packet-Switched NetworkCLI Command Line Interface

CoMP Coordinated MultipointCSID Clock Source IDDave average minimum Delay

DF RMS Delay Floor RMSDNC Digital Node ClockDSL Digital Subscriber LineDSLAM Digital Subscriber Line Access Multiplexer

EEC Ethernet Equipment Slave Clock G.8262

ek Instantaneous delay errorELC1 Ethernet Line Card in 8630 Smart Router, 8660 Smart RouterELP Ethernet Link Protection

EPC Evolved Packet Core

FDD Frequency Division Duplex

FOPS Full On-Path Support

GE Gigabit EthernetGLONASS Globalnaya Navigatsionnaya Sputnikovaya Sistema, i.e Global Navigation Satellite

SystemGMC Grand Master ClockGNSS Global Navigation Satellite SystemsGPS Global Positioning System

G.SHDSL An International standard for SHDSL

NTR Network Timing ReferenceOAM Operations, Administration and MaintenanceOCXO Oven Controlled Oscillator

OSSP Organizational Specific Slow ProtocolOTN Optical Transport Network

OUI Organizational Unique Identifier - ITU-T has a 3-octet IEEE assigned

Organizationally Unique Identifier (OUI), that is used to provide Quality Levelinformation over Synchronous Ethernet

PDN GW Packet Data Network Gateway (a.k.a P-GW)PDV Packet Delay Variation

PDH Plesiochronous Digital HierarchyPDU Protocol Data Unit

PEC Packet Equipment ClockPPP Point-to-Point Protocolpps Packet Per SecondPHP Penultimate Hop PoppingPOPS Partial On-Path Supportppb parts-per-billionppm parts-per-millionPRC Primary Reference ClockPRS Primary Reference SourcePRTC Primary Reference Time ClockPTP Precision Time ProtocolPTSF Packet Timing Signal FailPWE3 Pseudowire Emulation Edge to Edge

QoS Quality of Service

RNC Radio Network Controller

SASE Stand Alone Synchronization EquipmentSAToP Structure-Agnostic Time Division Multiplexing over PacketSCI Station Clock Input

SCI Station Clock InterfaceSCM Switching Control Module used in the 8611 Smart RouterSCO Station Clock Output

SDH Synchronous Digital HierarchySEC SDH Equipment ClockSETG Synchronization Equipment Timing GeneratorSEM Synchronous Ethernet Master

S-GW Serving Gateway

SSU Synchronization Supply UnitSyncE Synchronous EthernetT-BC Telecom Boundary Clock

TDD Time Division DuplexTDM Time-Division MultiplexingT-GM Telecom Grand MasterTIE Time Interval ErrorTLV Type Length Value

T-TSC Telecom Time Slave Clock

TX Transmit, TransmitterUDP User Datagram Protocol

VRF Virtual Routing and ForwardingVSCI Virtual SCI

WTR Wait-to-RestorexDSL A collective term referring to any of the various types of DSL technologies

Table of Contents

About This Manual 13

Objectives 13

Audience 13

8600 Smart Routers Technical Documentation 13

Interface Numbering Conventions 17

Document Conventions 17

Documentation Feedback 17

8600 Smart Routers Discontinued Products 18

1 Network Synchronization Evolution 19

1.1 Synchronization Terminology 19

1.2 Synchronization with 8600 Network Elements 20

1.3 Reference Clock Distribution 21

1.3.1 Traditional Distribution Schemes 21

1.3.2 Synchronous Ethernet 24

1.4 Packet Synchronization Overview 26

1.4.1 Synchronization Flow 28

1.4.2 Phase/Time Synchronization 29

1.5 GNSS Synchronization 31

2 Physical Layer Frequency Synchronization 34

2.1 Equipment Clock 34

2.1.1 Equipment Clock Architecture 35

2.1.2 Holdover and Freerun 36

2.2 Reference Clock Inputs 36

2.3 Station Clock Ports 37

2.3.1 Limitations and Restrictions 38

2.4 Synchronous Ethernet Interfaces 39

2.4.1 SyncE Interfaces Capability 39

2.5.2 Node Timing from Input Port 48

2.5.3 Synchronization from Co-Located Equipment 49

2.5.4 Connecting to Local Synchronization Equipment (BITS or SASE) 50

2.6 Loop Timing 51

3 Packet Frequency Synchronization 52

3.1 8600 NEs Functionality 52

3.2 Adaptive Timing (CES) 53

3.2.1 ACR From TDM PWE3 54

3.2.2 PDV Problem 55

3.2.3 Jitter Buffer Operation 57

3.2.4 Jitter Buffer Configuration 59

3.2.5 ACR Sources of Wander 60

3.2.6 Limitations and Restrictions 62

3.3 PTP Frequency Synchronization 62

3.3.1 PTP Frequency Telecom Profile 63

3.3.2 PTP Frequency Telecom Application 64

3.3.3 PTP Messages Exchange 65

3.3.4 PTP Clock Selection and Protection 66

3.4 PEC Performance 69

3.4.1 Temperature Stability 70

3.5 Typical ACR Performance 70

4 Phase/Time Synchronization 72

4.1 8600 NEs Capabilities 72

4.1.1 8600 NEs Time Model 73

4.2 Time Clock 74

4.2.1 Local Time Interface 75

4.2.2 GNSS Interface 77

4.2.3 PTP Fallback 78

4.2.4 PTP Profiles for Phase/Time 79

4.2.5 Multicast PTP Messages Exchange 80

4.2.6 Time Selection Algorithm 81

5 Packet Phase/Time Synchronization 83

5.1 T-BC Distribution Model 83

5.2 Mobile Networks Phase/Time Application 85

5.2.1 Central Phase/Time Distribution 85

5.2.2 Hybrid Synchronization Distribution on the Edge 87

5.2.3 Phase/Time Distribution (L2 Applications) 87

5.2.4 Phase/Time Distribution (L3 Applications) 88

5.2.5 Combined Synchronization Distribution Methods 90

6 Monitoring Synchronization 91

6.1 PTP Input Clock Quality Monitoring 91

6.1.1 Delay Distribution Statistics 92

6.1.2 Input Clock Quality Metric 92

6.2 PTP Output Clock Monitoring 93

6.3 PDV Statistics Monitoring 95

6.4 PTP Monitoring Capabilities 95

7 References 97

8 Frequency Synchronization Configuration Examples 98

8.1 PRC Reference 99

8.1.1 NODE-1 FBL Configuration (STM-N Synchronization Trail) 100

8.2 Reference Timing via Station Clock Ports 100

8.2.1 NODE-2 Configuration 101

8.2.2 Clock Source ID Configuration 104

8.3 Synchronous Ethernet Reference 104

8.3.1 NODE-3 FBL Configuration (SyncE Synchronization Trail) 105

8.3.2 Setting Clock Source ID 106

8.4 GMC Reference 106

8.4.1 Timing Mode 108

8.4.2 Loopback Address Configuration 108

8.4.3 NODE-4 (PTP Slave) FBL Configuration 108

8.4.4 NODE-5 FBL (PTP Slave) Configuration 109

8.5 Monitoring Synchronization Performance 110

8.5.1 Node Clock Status 111

8.5.2 PTP Statistics 114

8.5.3 PTP PDV Statistics 115

8.5.4 PTP Input Clock Monitoring 117

8.5.5 Output Clock Monitoring 118

8.5.6 PTP Fault Status 120

9 Supplementary Frequency Synchronization Settings 122

9.1 8605 Smart Router SCO Port Configuration 122

9.2 Forced Operation 122

9.2.1 Holdover 122

9.2.2 Freerun 123

9.2.3 Lower Priority Reference Clock 123

9.2.4 Disabling QL 123

9.3 Optional PTP Configurations 124

9.3.1 PTP VRF Routing Configuration 124

10 CES Synchronization Configuration Examples 126

10.1 Adaptive Timing Configuration 126

10.1.1 SAToP Configuration 126

10.1.2 Node #1 Configuration 126

10.1.3 Node #2 Configuration 127

10.1.4 CESoPSN Configuration 128

10.1.5 Node #1 Configuration 128

10.1.6 Node #2 Configuration 128

10.2 Delay Transient Threshold 129

10.3 CES Monitoring 130

10.3.1 Adaptive Timing Status 130

10.3.2 Adaptive Timing PDV Statistics 130

10.3.3 Adaptive Timing Fault Status 131

11 Phase/Time Synchronization Configuration Examples 133

11.1 Phase/Time L2 Applications 133

11.1.1 NODE-1 Configuration 135

11.1.2 NODE-2 Configuration 136

11.1.3 NODE-3 Configuration 136

11.1.4 Optional T-BC Settings 137

11.1.5 Configuration Verification and Diagnostics 137

11.2 Hybrid Synchronization 144

11.2.1 Node T-GM-3 Configuration 145

11.2.2 Node T-BC-5 Configuration 146

11.2.3 Configuration Verification and Diagnostics 146

11.3 Phase/Time L3 Applications 148

11.3.1 Node T-GM-1 Configuration 149

11.3.2 Node T-BC-1 Configuration 150

11.3.3 Node T-BC-2 Configuration 150

11.3.4 Node T-BC-3 Configuration 151

11.3.5 Configuration Verification and Diagnostics 152

11.4 PTP Fallback Configuration 155

11.4.1 NODE1 (T-GM) Configuration 157

11.4.2 NODE2 Configuration 158

Network Synchronization Configuration Listings 159

Synchronization Configuration Snapshots 159

Troubleshooting Synchronization Problems 164

Physical Layer Synchronization 164

Packet Synchronization 165

About This Manual

This chapter discusses the objectives and intended audience of this manual, 8600 Smart Routers

Synchronization Configuration Guide and consists of the following sections:

This manual provides an overview of the 8600 Smart Routers synchronization and instructions

on how to configure it with a Command-line Interface (CLI) using a router’s console or remoteterminal (telnet)

Audience

This manual is designed for administration personnel for configuring 8600 Smart Routers functionswith CLI On the other hand, 8000 Intelligent Network Manager provides access to equal

functionality for administration personnel with a graphical user interface

It is assumed that the readers have a basic understanding of networks, networking principles andnetwork configuration This manual also assumes that the readers are familiar with principles

of network synchronization

8600 Smart Routers Technical Documentation

The document numbering scheme consists of the document ID, indicated by numbers, and thedocument revision, indicated by a letter The references in the Related Documentation table beloware generic and include only the document ID To make sure the references point to the latestavailable document versions, please refer to the relevant product document program on the Tellabsand Coriant Portal by navigating towww.portal.tellabs.com> Product Documentation & Software

> Data Networking > 8600 Smart Routers > Technical Documentation

Document Title Description

8600 Smart RoutersATM and TDM Configuration Guide(76.8600-50110)

Provides an overview of 8600 NEs PWE3 applications,including types, Single-Segment and Multi-Segment; PWE3Redundancy; ATM applications, including PWE3 tunnelling,Traffic Management, Fault Management OAM, protection andTDM applications as well as instructions on how to configurethem with CLI

8600 Smart RoutersBoot and Mini-ApplicationsEmbedded Software Release Notes(76.8600-50108)

Provides information related to the boot and mini-applicationssoftware of 8605 Smart Router, 8607 Smart Router, 8609Smart Router, 8611 Smart Router, 8620 Smart Router, 8630Smart Router and 8660 Smart Router as well as the installationinstructions

8600 Smart RoutersCLI Commands Manual(76.8600-50117)

Provides commands available to configure, monitor and maintain

8600 system with CLI

8600 Smart RoutersEmbedded Software Release Notes

8600 Smart Routers SR7.0 Embedded Software Release Notes(76.8670-50177) for the following products:

Provides an overview of 8600 system HW inventory, softwaremanagement, equipment protection 1+1 (CDC and SCM) as well

as instructions on how to configure them with CLI

8600 Smart RoutersEthernet Configuration Guide (76

8600-50133)

Provides an overview of 8600 system Ethernet applications,including interfaces; Ethernet forwarding (MAC Switching,Ethernet PWE3, IRB, VLAN, VPLS); Ethernet OAM; LAG;ELP as well as instructions on how to configure them with CLI

8600 Smart Routers Smart RoutersFault Management ConfigurationGuide (76.8600-50115)

Provides an overview of 8600 system fault management,including fault source, types and status as well as instructions onhow to configure it with CLI

8600 Smart RoutersFrame Relay Configuration Guide(76.8600-50120)

Provides an overview of 8600 system Frame Relay applications,including interfaces; Performance Monitoring; protection; TrafficManagement as well as instructions on how to configure themwith CLI

8600 Smart RoutersHardware Installation Guide(76.8600-40039)

Provides guidance on mechanical installation, cooling,grounding, powering, cabling, maintenance, commissioning andESW downloading

Document Title Description

8600 Smart RoutersInterface Configuration Guides The Interface Configuration Guides provides an overview of the8600 NEs interface functions, including NE supported interface

types and equipping; interface features; configuration options andoperating modes; fault management; performance monitoring;interface configuration layers and port protocols as well asinstructions on how to configure them with CLI The followinginterface configuration guides are available:

• 8600 Smart Routers Network Interfaces ConfigurationGuide (76.8600-50161) (for 8602 Smart Router, 8615 SmartRouter and 8665 Smart Router)

• 8609 Smart Router and 8611 Smart Router FP7.0 InterfaceConfiguration Guide (76.8670-50179)

• 8600 Smart Routers FP7.0 Interface Configuration Guide(76.8670-50180) (for 8630 Smart Router and 8660 SmartRouter)

8600 Smart Routers

IP Forwarding and TrafficManagement Configuration Guide(76.8600-50122)

Provides an overview of 8600 NEs IP, forwarding and trafficmanagement functionality, including: IP addressing; IP hosting(ARP, DHCP); IP routing (static); ACL; Differentiated Services(Policing, Queue Management, Shaping) as well as instructions

on how to configure them with CLI

8600 Smart RoutersManagement CommunicationsConfiguration Guide

(76.8600-50125)

Provides an overview of 8600 system managementcommunications functions, including communication protocols:BMP; FTP; RADIUS; SNMP; SSH; TELNET as well asinstructions for configuring them with CLI

8600 Smart RoutersMobile Optimization ConfigurationGuide (76.8600-50100)

Provides an overview of 8600 system Mobile Optimizationapplications as well as instructions on how to configure themwith CLI

8600 Smart RoutersMPLS Applications ConfigurationGuide (76.8600-50123)

Provides an overview of 8600 NEs MPLS applications (includingFRR (one-to-one and facility backup); LDP; protection andTraffic Engineering), MPLS-TP applications (including OAM,linear protection), S-MPLS applications as well as instructions

on how to configure them with CLI

8600 Smart RoutersPerformance Counters ReferenceGuide (76.8600-50143)

Provides an overview of 8600 system supported performancecounters

Document Title Description

8600 Smart RoutersReference Manuals The reference manuals describe the 8600 network elementfeatures including:

• NE enclosure, baseboard, power supply modules, andinterfaces in 8602 Smart Router FP7.0 Reference Manual(76.8670-40130)

• NE enclosure, baseboard, power supply modules, interfacesand physical LM types in 8609 Smart Router FP7.0 Refer-ence Manual

• NE enclosure, baseboard, power supply modules, SCMs, HMand LM types in 8611 Smart Router FP7.0 Reference Manual

• NE enclosure, baseboard, power supply modules, and terfaces in 8615 Smart Router FP7.0 Reference Manual(76.8670-40132)

in-• NE subrack, fan modules, CDCs, line cards and IFMs in 8630Smart Router FP7.0 Reference Manual

• NE subrack, fan modules, CDCs, line cards and IFMs in 8660Smart Router FP7.0 Reference Manual

• NE subrack, fan modules, line unit and switch unit in 8665Smart Router FP7.0 Reference Manual (76.8670-40128)

8600 Smart RoutersRouting Protocols ConfigurationGuide (76.8600-50121)

Provides an overview of 8600 NEs routing protocols, includingBFD; BGP; BGP MP; ECMP; IS-IS; OSPF and VRRP as well asinstructions on how to configure them with CLI

8600 Smart RoutersScalability Reference Manual(76.8600-50160)

Provide a summary of tested scalability limits of the 8600 SmartRouters

8600 Smart RoutersSNMP MIB Support(76.8600-50116)

Describes SNMP MIB support by the 8600 NEs and providesinformation on the supported objects and traps For furtherinformation on SNMP MIBs, see the related RFCs

8600 Smart RoutersStatistic Counters Reference Guide(76.8600-50142)

Provides an overview of 8600 system supported statistic counters

8600 Smart RoutersSynchronization ConfigurationGuide (76.8600-50114)

Provides an overview of 8600 NEs synchronization functionality,including physical layer Frequency Synchronization (SEC, EEC);PTP Frequency Synchronization; Phase-Time Synchronization(L2 and L3 applications) as well as instructions on how toconfigure them with CLI

8600 Smart RoutersTest and Measurement ConfigurationGuide (76.8600-50124)

Provides an overview of 8600 NEs measurement and connectivityverification tools, including Ethernet loopback; IP ping andtraceroute; MAC swap loopback; MPLS ping and traceroute;PLT; PWE3 loopback; VCCV (BFD, LSP ping) as well asinstructions on how to configure them with CLI

8600 Smart RoutersVPNs Configuration Guide(76.8600-50128)

Provides an overview of 8600 system virtual private network(VPN) layer 3 applications as well as instructions on how toconfigure them with CLI

8000 Intelligent Network ManagerOnline Help Provides instructions on how different operations are performedwith the 8000 Intelligent Network Manager Describes also

different parameters and controls of the 8000 Intelligent NetworkManager dialogs and windows

Note that the Online Help is not available on the Portal but it isincorporated in the 8000 Intelligent Network Manager

Interface Numbering Conventions

To be able to follow more easily the feature descriptions and configuration examples given in this

document, see also the 8600 system interface numbering and related figures described in 8600

Smart Routers CLI Commands Manual.

Document Conventions

This is a note symbol It emphasizes or supplements information in the document.

This is a caution symbol It indicates that damage to equipment is possible if the instructions are not followed.

This is a warning symbol It indicates that bodily injury is possible if the instructions are not followed.

Documentation Feedback

Please contact us to suggest improvements or to report errors in our documentation:

Email: fi-documentation@tellabs.com

8600 Smart Routers Discontinued Products

8600 Smart Routers Manufacture Discontinued (MD) notifications are available on the Tellabsand Coriant Portal,www.portal.tellabs.com > Product Documentation & Software > Data Networking > [8600 Smart Router product name] > Product Notifications.

1 Network Synchronization Evolution

Synchronization has evolved from being a central pillar of the TDM transport network to being

a service that is required by the end applications (and not internally by the transport network) Inparticular mobile networks require reliable synchronization services and are indifferent as to howthese services are provided Usually, it is desirable to have synchronization services provided overthe packet transport network, but it is also common to use legacy TDM networks, or a distributedsynchronization scheme, e.g Global Navigation Satellite Systems (GNSS)

For many years the main requirements of mobile networks (2G/3G or LTE) has been a frequencyaccuracy of 50 ppb at the air interface The Long Term Evolution (LTE) technologies have quitedifferent synchronization requirements Mobile networks based upon Time Division Duplex(TDD), e.g LTE TDD, require that neighboring base stations share a common concept of phase.The requirements for phase synchronization are coming also into Frequency Division Duplex(FDD) networks with the advent of LTE-Advanced (LTE-A) services, e.g Coordinated Multipoint(CoMP) An overview of the different levels of phase accuracy for different applications is shown

in the following table

Phase Accuracy Levels Level of Accuracy Range of Requirements Typical Applications

Boundary Clock (BC) A clock that has multiple Precision Time Protocol (PTP) ports

in a domain and maintains the timescale used in the domain Itmay serve as the source of time (i.e be a master clock), or maysynchronize to another clock (i.e be a slave clock)

Equipment Clock (EC) A clock that filters the frequency input and distributes it to the

frequency output interfaces Input/output interfaces can be e.g.Ethernet, SDH, or dedicated station clock ports

Frequency synchronization When the phase difference between two clocks is constant (on

average) the clocks are said to be frequency synchronized

Term Description

Phase/Time synchronization When the phase difference between two clocks is zero (on

average) and also the calendar times are aligned, the clocks aresaid to be phase/time synchronized

Primary Reference Clock (PRC) A reference frequency standard that provides a reference

frequency signal compliant with Recommendation G.811.Typically a GPS (GNSS) clock or a Caesium atomic clock.Primary Reference Time Clock

(PRTC)

A reference time generator that provides a reference timingsignal traceable to an internationally recognized time standard(e.g UTC) Typically a GPS (GNSS) clock

Pulse Per Second interface (1PPS) One pulse-per-second (1PPS) phase and time synchronization

interface (e.g for IEEE1588 or GNSS clock)Telecom Boundary Clock (T-BC) Telecom Boundary Clock (T-BC) is a device consisting of

a boundary clock as defined in [IEEE1588-2008] and withadditional performance characteristics defined in [G.8273.2].Telecom Grandmaster (T-GM) A device consisting of a grandmaster clock as defined

in [IEEE1588-2008] and with additional performancecharacteristics, which are for further study at the ITU-T

Telecom Time Slave Clock (T-TSC) A device consisting of a PTP slave only ordinary clock as

defined in [IEEE1588-2008] and with additional performancecharacteristics, which are for further study at the ITU-T

Time of Day (ToD) The information displayed by a clock or calendar, i.e the hour,

minute, second, month, day and year

Time Clock A clock that filters the phase/time input and distributes it to

the phase/time output interfaces Input/output interfaces can

be e.g PTP or 1PPS

A 8600 Network Element (NE) provides accurate synchronization services for a variety of differentmobile applications, including the stringent phase requirements presented above inPhase AccuracyLevels The NEs include support for physical layer synchronization using the TDM links (i.e.traditional Synchronous Digital Hierarchy (SDH) and Synchronous Optical Network (SONET)) andSynchronous Ethernet (SyncE) links, as well as packet synchronization schemes using the PrecisionTime Protocol (PTP), also referred as IEEE1588 All these technologies are seamlessly integratedallowing the customers to select and mix the solutions on a per network basis

The 8600 NEs support high accuracy time synchronization by using the PTP Telecom BoundaryClock (T-BC) function In order to ensure that the performance requirements are always met,the path between the PTP master and the base station requiring time synchronization, must havesupport for PTP in every node

While frequency synchronization and phase/time synchronization are generally independent layers,the time layer is also able to benefit from a stable Primary Reference Clock (PRC) traceablereference, if such is available This will be discussed further in the following sections of thisdocument

1.3 Reference Clock Distribution

It is important to note that almost all point-to-point link technologies used in telecommunications aresynchronous In TDM networks synchronization is recovered from the links and distributed withinthe node to the egress links A local clock minimized the effect of switching between references andprovided holdover in the case when all the input references are lost

The 8600 NEs provide the same synchronization mechanisms as used in SDH/SONET allowing

a highly accurate reference source to distribute synchronization to the end devices Normally, aPrimary Reference Clock (PRC, Stratum 1) is duplicated for protection and is used as the mainsource

The same physical layer synchronization is also available when using SyncE, the specifications arecompatible and also the quality level mechanism has been keep completely inter-operable betweenSDH/SONET and SyncE

1.3.1 Traditional Distribution Schemes

The SDH and SONET core networks are usually synchronised from redundant PRC/Stratum 1using a carefully planned hierarchical synchronization network A 8600 NE, when placed at theedge of the core network can take reference clock from SyncE or STM-N/OC-N links connected

to the core network equipment, synchronize the NE to this clock, and then distribute this clockdownstream This scheme provides a relatively simple architecture where potential problems, such

as timing loops are avoided

Fig 1 Synchronization Distribution

One mechanism that assists in ensuring that the synchronization network is operational isSynchronization Status Messages (SSM) The principle of SSM is to provide an indication ofclock traceability In the case where the synchronization network is of a tree structure this meansthat traceability to a PRC reference is propagated down the tree Each link carries the SSM andeach node processes the SSM The Quality Level (QL) indicated in the SSM indicates the clockstandard to which the node believes itself to be traceable When a node does not have traceability

to an external reference, it uses the QL of its local oscillator, which is usually an SDH EquipmentClock (SEC), or an Ethernet Equipment Slave Clock (EEC) or a Stratum Level in the case of ANSInetworks It is important to note that the SDH links and SyncE links can be combined in the samenetwork freely as both the physical layer synchronization and the QL messages are compatible

In more complex scenarios, like ring topologies there is a need to use QL Do-Not-Use to ensure that

timing loops are not created when direction on the ring changes

Another synchronization scheme uses reference clocks transported by other means, such as theGNSS (see1.5 GNSS Synchronization) When building a new network there may often beco-located equipment, which has a good quality synchronization reference While the new networkand the old may not share the same services, synchronization can be provided by the existingnetwork A local reference clock can be supplied to the 8600 NE via its station clock input ports.

It is important to note that synchronization can be carried over a number of different technologies.The 8600 NEs can act as bridges in carrying synchronization from one link technology to another Anumber of different scenarios are shown in the following figure

Fig 2a) shows synchronization being taken from an independent co-located equipment Forexample, this could be a leased line supplying a 2G BTS.Fig 2b) shows a traditional SONETnetwork being used to provide synchronization WhileFig 2c) shows synchronization beingprovided by SyncE.

In some applications there is no possibility to derive synchronization from the physical layer Inthis case, the only options available are GPS, or Precision Time Protocol (PTP), or adaptive timing.Fig 2d) shows an example where adaptive timing is used to provide synchronization over anexisting network that does not support physical layer synchronization techniques

A combination of synchronization technologies are shown inFig 2e) Here SyncE is used to carrysynchronization to the DSLAM, which then provides the synchronization via DSL to the cell sites.This requires that the DSLAM is capable of forwarding synchronization A similar diagram could

be envisaged where the DSL links are replaced with microwaves radio links

Synchronization can be carried over DSL using different techniques When the bit rate is constant,

it is possible to use the symbol rate in similar way as in SyncE Otherwise, an 8 kHz clock signalknown as Network Timing Reference (NTR) is used instead The 8607 Smart Router supportsclock recovery from G.SHDSL using the line symbol rate However, it should be noted that NTR

is not supported

InFig 2f) here synchronization is being transferred as a PTP packet flow from the PTP Master tothe 8605 Smart Router, which contains a PTP slave function The PTP slave recovers the clockfrequency using adaptive clock recovery function It is important to note that the PTP flow doesnot need to traverse the network end-to-end The PTP masters may be distributed throughout thenetwork, and it is advantageous to use one that is local to the PTP slave node It is assumed that thenodes on the path of the PTP flow are not able to provide any support to reduce the effects of PDVother than to provide traffic forwarding (preferably with minimal delay)

1.3.2 Synchronous Ethernet

In practice SyncE is a direct analogue of traditional SDH techniques In traditional Ethernetinterfaces the physical layer clock is only used within the physical receiver device for data recovery.With SyncE the TX clock is locked to the reference of the upstream node and in the downstreamnode the recovered clock is extracted and used as a synchronization reference

The Ethernet Equipment Slave Clock (EEC) is defined in [G.8262], in practice this is identical to theSDH Equipment Clock (SEC) specified in [G.813]

In equipment where there are no SDH interfaces the term EEC is used The 8600 NEs meetthe requirements of both EEC and SEC Thus, each port that fully supports SyncE provides asynchronization candidate for the equipment clock being it SEC or EEC

Fig 3 SyncE Clock Distribution

When designing a network for SyncE the following conditions must be met:

• SyncE requires direct L1 link between the supporting nodes

• Care must be taken to ensure that a link path does not contain or traverse:

• Ethernet media adaptors or converters

• Legacy Ethernet switches or routers

• OTN tunnels (unless the mapping used supports bit-transparency)

• Other Ethernet tunnelling protocols

1.4 Packet Synchronization Overview

Mobile networks require synchronization between the adjacent base stations to meet 3GPPrequirements Leaving technologies aside for a moment, the fundamental question is, which clockcan be used to synchronize the mobile network If the core network has a PRC traceable clockone option would be for the operators to agree that the core network would provide networksynchronization as part of the service The mobile network could then use synchronization from thecore network Such arrangement assumes that the technology is available to make this practical andthat necessary Service Level Agreements (SLAs) can be arranged This represents the traditionalsynchronization distribution model based upon SDH or SyncE In practice, this still requires thatthe core network uses either SyncE or SDH, or Optical Transport Network (OTN) with suitablemappings and interfaces

Fig 4 Mobile Network Synchronization Concept

Fig 4shows a typical mobile network, where it can be seen that the service network is nothomogenous end-to-end but rather consists of a number of islands interconnected by at least onecore network The synchronization capabilities of these network fragments usually differ as mayownership and operational responsibility SyncE is usually the preferred mechanism for carryingsynchronization across all islands of the packet network, but SyncE is not always available Whereneither SyncE nor GPS is available the only remaining option is to use packet synchronization.The trend away from circuit switched transport towards a common packet switched networkusing technologies such as Ethernet and IP/MPLS has made for changes in how synchronizationcan be provided SyncE has become available and together with OTN can provide robust layer

1 synchronization The circuit emulation provides a well known mechanism for carrying TDM(E1/T1) circuits over the PSN Only the Circuit Emulation Service (CES) end points need to besynchronized while the intermediate nodes need only a packet forwarding function

Fig 5 Packet Synchronization Methods

With CES, the synchronization flow is specific to the individual port, i.e each E1/T1, and the TDMpseudowire carries synchronization derived from the incoming TDM port This represents theservice synchronization of the TDM far-end port and not the clock of the upstream transport node.The TDM pseudowire is not used as a node reference in the 8600 NEs

A time protocol such as Precision Time Protocol (PTP) can be used to carry synchronization acrossany network The “precision” of such synchronization depends on the extent that the networksupports PTP Since telecom networks do not support PTP (as with CES synchronization), the PTPsynchronization flow is carried transparently as data traffic across the packet network Due to packetdelay variation and the fact that packet synchronization support in the transport networks is still

to achieve maturity, the core network is unlikely to offer synchronization as a service using PTP

as the distribution technology In this case, the service operator has no choice, but to use ownsynchronization source, which then represents a service clock

There can be four options for synchronization of the service network:

• Network clock via layer 1 - receive synchronization from the core network

• Service clock via CES - end-to-end across the core network

• Service clock via PTP - end-to-end across the core network

• GNSS - Global Navigation Satellite Systems distributed clock

Network Clock - For frequency distribution where the network is based upon SyncE, SDH, or OTN

there is the option to use the network clock to synchronize the service As already mentioned the

Service Clock via CES - The service clock can be provided by CES connections using adaptive

clock recovery from TDM pseudowires The quality of the derived service clock is then dependent

on the performance of Adaptive Clock Recovery (ACR) and the accumulated PDV on the networkconnection In certain situations, usually where there is no other synchronization reference, aTDM pseudowire may be used to “apparently” synchronize multiple E1/T1 ports This situation

is common in mobile networks at the edge of the network, and especially where there is E1/T1replacement or pure 3G networks In such cases the recovered clock from the selected TDMpseudowire is mirrored to multiple TDM ports The end result is that it appears as if the nodewould be locked to the same TDM pseudowire

Service Clock via PTP - This implies an end-to-end data flow across the service and core networks.

This may take the form of a PTP master, say at a central office location, and PTP slaves at themobile cell sites The quality of the derived service clock is then dependent on the performance

of the PTP slave and the accumulated PDV generated on the network connection Since PTP is atwo-way protocol, then Packet Equipment Clock (PEC) can achieve better performance than CES

GPS/GNSS - GPS synchronization (see1.5 GNSS Synchronization) represents an example

of a distributed clock offering both PRC frequency traceability and accurate time of day Fortechnologies requiring phase/time synchronization GPS is currently the only available option.Usually the synchronization network is a hybrid of these options based upon the technical andeconomical constraints of individual networks Since network synchronization usually involvesTDM interfaces (E1 or T1) and legacy SDH networks it is considered reliable, but may have a highcost A suitable distribution of GPS synchronized PTP masters across the service network togetherwith high quality PTP slaves is an attractive solution from a cost standpoint, but synchronizationperformance depends on the intervening network performance Usually to accept this solution theoperator needs to have tight control over the network A connectivity from third parties puts thequality of the synchronization at risk and it is almost impossible to arrange an SLA that would beable to guarantee the necessary forwarding performance

1.4.1 Synchronization Flow

In a synchronization flow there are three ways the flow can be processed in 8600 NEs:

• Forwarded to egress as data (switching, or routing, or CES model)

• Terminated and available as synchronization candidate for the equipment clock (boundary clockmodel)

• Actively forwarded to egress as synchronization (transparent clock model)

A synchronization flow may be forwarded through the node without processing, i.e the flowenters and exits the node as a packet Examples of this model are the TDM pseudowires, or PTPsynchronization packets In this case, a node is not aware of the synchronization flow at all and willjust forward packet data with an usually good QoS class (for more details about traffic engineering

refer to 8600 Smart Routers MPLS Applications Configuration Guide and for IP traffic management refer to 8600 Smart Routers IP and Traffic Management Configuration Guide).

The traditional and preferred synchronization model is the boundary clock Here the incomingsynchronization flow is terminated to the equipment clock assuming it is the primary candidate onthe Fallback List (FBL), and a new synchronization flow synchronous to the equipment clock isregenerated and propagated via the downstream links

Finally a synchronization flow may be processed ”on the fly” and passed on to a physical port Asimple example of this is port re-timing from a TDM pseudowire, i.e an E1/T1 carrying ATM isbeing re-timed from a TDM pseudowire or one TDM pseudowire is re-timing another port Thissituation is forced when many Nx64k TDM pseudowires are egressing on the same physical E1/T1port Another example of this would be the ”on the fly” processing required by PTP transparentclock.

1.4.2 Phase/Time Synchronization

Mobile standards with phase/time synchronization requirements for 1 microsecond phase alignment,e.g LTE advanced services create drivers for change in the synchronization networks and thetechnologies used If the transport networks could support phase/time delivery this would reducedependence on GNSS and result in lower total equipment cost PTP is currently the main candidatefor adding accurate phase/time synchronization to the transport network Some specific technologieshave the native capability built-in to support accurate phase/time delivery The most notable beingPassive Optical Network (PON) There are proposals to add extensions to SyncE to support phase(and time) The PTP profiles for supporting phase/time in telecoms network are under development

in the ITU-T

PTP defines three clock types:

• Ordinary clocks - which can be slaves, masters or grand masters

• Telecom Boundary Clocks (T-BC) where the same node may behave simultaneously as slave andmaster

• Transparent clock - where the main function of the nodes is a compensation of delay

Ordinary Clock

PTP is a protocol that seeks to discover and build a clock hierarchy such that within the specifieddomain one ordinary clock is elected as the master and the remaining ordinary clocks are slaves.Slave clocks synchronize to the master clocks PTP has the concept of a slave-only ordinary clock

An example of a slave-only ordinary clock is illustrated inFig 6:

PTP messages are exchanged between a master clock and a slave clock Ordinary clocks in the slavestate do not exchange PTP messages with other ordinary clocks in the slave state.

Telecom Boundary Clock

In PTP, to extend the synchronization hierarchy beyond one layer a Telecom Boundary Clock(T-BC) function is required The T-BC has multiple synchronization ports and maintains the timescale used in the PTP domain At least one of the PTP ports operates as a slave and providessynchronization for the node, the other ports then operate as masters and propagate synchronization

to other clocks within the domain

Fig 7 T-BC Hierarchy

Transparent Clock

Transparent Clock (TC) can be considered as a forwarding function that provides certain corrections

to certain PTP event messages There are two variants of TC, which differ in the type of correctionsapplied and the messages to which they are applied Both variants of TC contain a residence timebridge function that measures the time of the message in the bridge, i.e the time of a message

is stored in the node before being forwarded

The end-to-end transparent clock applies the residence time to the correction field of thesynchronization messages In this model the delay is processed end-to-end

Peer-to-peer TC contains a residence bridge, but also actively calculates the peer-delay for eachport, i.e the delay to the next peer-to-peer TC master or slave Only the correction field of thesynchronization messages are corrected and the correction contains both the residence time andthe link delay components

Delay request messages are not forwarded by peer-to-peer TC and the two model of TC areincompatible and must not be used in the same time distribution chain, i.e there must be a boundaryclock between regions using end-to-end TC and regions using peer-to-peer TC.

Fig 8 PTP Transparent Clock Hierarchy

Global Navigation Satellite System (GNSS) is a navigation system consisting of a set of satellitesthat provide autonomous positioning with global coverage GNSS allows the receivers to determinetheir location with high precision using time signals transmitted by the satellites These signals canalso be used to calculate the current local time with high precision, which allows phase/time andfrequency synchronisation

The GNSS satellites are at “MEO” (Medium Earth Orbits) at the height of about 20000 km.Typically there are 4–8 satellites on the same orbital plane and 3–6 evenly spaced orbital planesaround the globe From the users location the satellites are seen as rising and setting arcs at differentangles Each location has a different sky visibility mask which affects to the reception The userantenna has to see at least 4 satellites to be able to calculate the solution for place and time If moresatellites are visible the solution becomes more accurate and reliable

There are currently two fully operational GNSS systems:

• GPS – the United States’ Global Positioning System that consists of up to 32 MEO satellites insix different orbital planes, with exact number of active satellites varying as older ones are retiredand replaced GPS has been operational since 1978 and globally available since 1994 GPS iscurrently the most common satellite navigation system.

• GLONASS – the Russian Global Navigation Satellite System, which has 24 satellites in the orbitand the constellation is full for global navigation The average lifetime for GLONASS satelliteshas been quite low compared to GPS, but it is improving all the time and the constellation can beconsidered as stable Also the accuracy of GLONASS has improved to almost GPS levels TheGPS error is still smaller and it is recommended that GPS is used

There are also other GNSS systems being built, e.g.:

• Galileo (the European system)

• Compass/BeiDou II (the Chinese system)

Fig 9 GNSS Synchronization Application

The 8600 GNSS module is implemented as an SFP, which is powered and managed as an integralpart of the 8600 NE Together with the synchronization capabilities of the 8600 NEs, this offers acost effective method for two main applications:

• Phase/time synchronization for LTE TDD or LTE-A, in which the GNSS SFP module provides aPrimary Time Reference Clock (PRTC) function for a grandmaster or boundary clock

• Frequency synchronization for 2G/3G, in which the GNSS SFP module can be used to provideSyncE (SyncE Master (SEM) functionality) at the edge of SyncE unaware networks

The GNSS SFP supports both active and passive antennas through a micro coaxial (MCX)connector For an optimal synchronization quality, the active antenna with maximum sky visibility

is recommended For more details, please refer to 8600 Smart Routers Hardware Installation Guide.

In 8600 NEs, GNSS synchronization can be enabled either through the 1PPS/ToD, or GNSS SFPinterface(s)

2 Physical Layer Frequency Synchronization

Fig 10 Node’s Equipment Clock

Fig 10provides a general overview of the 8600 NE internal clock generator blocks that comprise an

EC The EC can be synchronized to a service clock via PEC (PTP frequency application) In thiscase, PEC provides a Virtual Station Clock Input (VSCI) reference candidate to the FBL

In 8630 Smart Router/8660 Smart Router, the EC is implemented in CDC (Control and DC powercard) Within these NEs two CDC cards are used for protection In this case, the active CDCholds the NE synchronization functionality configured and the protecting CDC will inherit thesame settings

In CDC1 and 8620 Smart Router the internal clock generator is implemented in the Timing Moduleand there are two types:

• SEC Timing Module, which supports only ETSI applications with SCI and SCO ports supporting

2048 kHz input Framing mode is not supported

• S3 Timing Module, which can be configured to operate either in Stratum 3 or SEC mode and theSCO ports can operate as 2048 kHz, framed E1 or framed T1 (see2.3 Station Clock Ports)

In 8665 Smart Router, the EC is implemented in LU1 However, there can only be a maximum

of two LU1 cards with an active EC functionality and these LU1 cards are the ones located atthe leftmost and the rightmost slots of the NE In this case, the active LU1 card holds the NEsynchronization functionality configured and the protecting LU1 card will inherit the same settings

It is worth to be noted that within the NE, the SCI, SCO and 1PPS ports in LU1 cards in-betweenslots cannot provide any synchronization functionality However, all the line interfaces in LU1 cards

in-between slots provide reference clock inputs and clock distribution normally Please refer to 8665

Smart Router Reference Manual for more details about the NE architecture.

In multi-slots NEs (8630 Smart Router, 8660 Smart Router, 8665 Smart Router), dedicatedbackplane links are used to distribute synchronization between the slots The EC receives twosynchronization reference signals from each slot Both the backplane links and the EC areduplicated for protection

In 8615 Smart Router stacked, the EC is also duplicated, which provides protection for thesynchronization functions In this case, an inter-unit synchronization distribution is performedvia the stacking cable

2.1.1 Equipment Clock Architecture

The following table presents an architectural summary of the Equipment Clock (EC) implementation

in 8600 NEs Please refer to 8600 Smart Routers Hardware Release Notes for more details about

the hardware and software dependences The notation “—” used in the following table stands fornot applicable in any case

Vari-ant/Unit

Timing Module

Timing Block

NE

Vari-ant/Unit

Timing Module

Timing Block

Clock Standard

8609 Smart Router — Yes Stratum 3 & G.813

8611 Smart Router — Yes Stratum 3 & G.813

8615 Smart Router — Yes Stratum 3 & G.8262

8620 Smart Router Yes — Stratum 3 & G.813

CDC1 Yes — Stratum 3 & G.813

8630 Smart Router

8660 Smart Router

CDC2 — Yes Stratum 3 & G.813

8665 Smart Router LU1 — Yes Stratum 3 & G.8262

2.1.2 Holdover and Freerun

The equipment clock has a holdover process by which, it learns the frequency of the referenceinto which, it is locked in about 20 minutes If the NE reference clocks are lost, the equipmentclock can maintain the frequency according to SEC and Stratum 3 specifications [G.813] and[GR-1244-CORE]

The operator can force the equipment clock to operate in holdover state when for example, thereference clocks are known to have quality problems

Usually the equipment clock is locked to a PRC traceable reference clock distributed via thesynchronization network using e.g SyncE links The equipment clock will acquire sufficientinformation to allow good quality holdover after being locked to a reference for about 20 minutes.During this time, the equipment clock displays the status “Locked Acquiring” Once theholdover memory is fully acquired, the equipment clock status changes to “Locked” If allsynchronization references are lost while the equipment clock is still acquiring a holdover, the nodewill enter the freerun state – where the factory calibrated frequency value is used If the equipmentclock loses all synchronization references after the holdover is acquired, then the node will enterholdover state

The operator can force the equipment clock to operate in a freerun mode, e.g when it is desired toclear the holdover memory

Force commands are not saved in a non-volatile memory and are not automatically restored,

if a power outage occurs Therefore, if a permanent equipment clock freerun operation is desired, the FBL should be empty In that case, the NE will use its freerun or holdover value

if learned.

The following table gives a summary of the interfaces that can be used to supply a reference clock tothe 8600 NEs The notations used below are as follows:

• “No” stands for not yet implemented/supported

• “—” stands for not applicable in any case

Reference Clock Inputs

Reference Line Interfaces Reference Synchronization

Ports NE

E1/T1

8602 SmartRouter

8605 SmartRouter

8607 Smart

8609 SmartRouter

8611 SmartRouter

8615 SmartRouter

8620 SmartRouter

8630 SmartRouter

8660 SmartRouter

8665 SmartRouter

All the reference line interface clock inputs are available as reference synchronization candidates forthe FBL, after the NE HW inventory has been created Also it is worth to be noted that the referencesynchronization port clock inputs must be first enabled before they can be taken into use

In 8600 NEs, the reference clock inputs signal is always monitored for a Loss of Signal defect.However, even if a reference clock input has a fault, it can be added to the FBL, but that clock willnot be selected until a fault is cleared

The station clock ports can be used for synchronizing a 8600 NE or distributing the synchronization

to other nodes The following table gives a summary of the station clock ports available in the 8600NEs and the modes supported by each station clock port

8600 NEs Station Clock Ports

One 2048 kHz

5/10/15/20MHz

2048 kHz5/10/15/20MHz

urable SCO FramedE1/2048

Config-kHz

Framed T1

8607 SmartRouter One FramedE1/2048

kHz

E1/2048kHz

Framed T1

8609 SmartRouter

One Framed

E1/2048kHz

E1/2048kHz

Framed T1

8611 SmartRouter One/two FramedE1/2048

kHz

Framed T1 One/two Framed

E1/2048kHz

Framed T1

8615 SmartRouter

One Framed

E1/2048kHz

E1/2048kHz

Framed T1

8615 SmartRouterstacked

Two Framed

E1/2048kHz

E1/2048kHz

Framed T1

8620 SmartRouter One FramedE1/2048

kHz

E1/2048kHz

Framed T1

8630 SmartRouter

One/two Framed

E1/2048kHz

Framed T1 One/two Framed

E1/2048kHz

Framed T1

8660 SmartRouter One/two FramedE1/2048

kHz

Framed T1 One/two Framed

E1/2048kHz

Framed T1

8665 SmartRouter One/two FramedE1/2048

kHz

Framed T1 One/two Framed

E1/2048kHz

Framed T1

For the NEs with redundant station clock ports (see8600 NEs Station Clock Ports), the two SCIclocks can be separately entered to the FBL Also the two SCO ports have a common port enablesetting, with each port outputting a clock signal

When the SCO auto-squelch is enabled and the node does not have a valid clock reference (i.e isoperating in holdover or in freerun mode), the SCO port signal will be squelched to prevent thepropagation of a poor quality clock signal

The 8605 Smart Router provides an option to configure a dedicated port from any of the E1/T1 ports

to operate as a clock output, i.e as an SCO The dedicated E1/T1 port when configured as an SCOcarries no data traffic and can be squelched as any other SCO port in the 8600 NEs

2.3.1 Limitations and Restrictions.

This chapter provides a list of known limitations and restrictions of station clock ports in 8605Smart Router:

• In 8605-D the T1 ports 7 and 15 cannot be configured as SCO, due to the fact that these ports arereserved for the DS3 interfaces.

• Once E1/T1 port has been set to SCO, it cannot be restored to E1/T1 traffic port without rebooting

a NE

• SSM SA-bit cannot be modified in 8611 Smart Router on the protecting SCM side SCI when using

the 8000 Intelligent Network Manager However, it is possible to modify with the node-timing

sci sci-slot ssm-sa-bit CLI command.

• Setting a PDH interface SSM SA-bit to any value other than the default (4) does not work

The 8600 NEs provide support of SyncE on Ethernet interfaces In most cases SyncE is fullysupported, i.e the line rate of the Ethernet signal is synchronous to the equipment clock, ESMCmessages are transmitted and the Ethernet interface can be used as a synchronization candidate forthe equipment clock

In existing synchronization distributions hierarchies, the synchronization flow is unidirectional fromthe upstream transmitter (PRC) towards the downstream receiver edge nodes Such hierarchycan be built using interfaces that support bidirectional synchronization, e.g optical links and areprovisioned to work in given roles Equally, unidirectional synchronization hierarchy can be builtwith electrical (100BASE-TX/1000BASE-T) SyncE interfaces with limited roles, i.e SyncE TXcapable or SyncE RX capable In this case, one end of the link is a clock master and the clock isterminated at the slave end Changing the clock direction means reversing the roles of master andslave and requires renegotiation of the link, causing short breaks in transmission In 8600 NEs, theroles of “SyncE TX capable” and “SyncE RX capable” are totally independent

SyncE supports a similar QL mechanism as in SDH called Ethernet Synchronization MessageChannel (ESMC), which is defined in [G.8264] The Ethernet SSM is an ITU-T defined Ethernetslow protocol with the following parameters:

• EtherType 0x8809 (Ethernet OAM Protocol IEEE 802.3ah)

• Organizational Specific Identifier 0x19A7

• Slow Protocol Subtype 0xA

• The SSM QL is carried in a Type Length Value (TLV) field, which is contained within the ESMCProtocol Data Unit (PDU)

2.4.1 SyncE Interfaces Capability

The following table provides an outline of SyncE interface capabilities in 8600 NEs, including theline cards (8630 Smart Router and 8660 Smart Router), and LU1 (8665 Smart Router) There aretwo types of connectivity supported for the physical medium of an Ethernet port (RJ-45 & SFP),which offer several variants of physical media interface types named as follows:

• Optical XFP/SFP+

• Optical CFP2

Please refer to 8600 Smart Routers Hardware Installation Guide for more details about the

supported SFP types The notations used below are as follows:

• “No” stands for not yet implemented/supported

• “—” stands for not applicable in any case

NE/Line Card Interface Type Interface Mode SyncE TX & RX

Electrical RJ-45

100BASE-TX/1000BASE-T YesElectrical

Electrical(1000BASE-T) SFP

SyncE electrical SFP

100BASE-TX/1000BASE-T

Yes8602-D

100BASE-TX Yes3

Electrical RJ-45

TX/1000BASE-T

100BASE-Yes

Electrical(1000BASE-T) SFP

100BASE-Yes

Electrical(1000BASE-T) SFP

Optical SFP 100/1000BASE-X Yes

3 SyncE is only supported in TX direction on ports 2 and 3.