Synchronization security - Planning a robust timing distribution architecture

Agenda

• Timing Standards Overview• PTP Distribution Architectures• Metro and National Phase Delivery Architecture

Structure of ITU-T Sync Requirements

LTE Services ToD/Phase Requirements

Basic Acronyms

• GM – Grand Master• PRC – Primary Reference Clock (Frequency)• ePRC – Enhanced Primary Reference Clock (Frequency)• PRTC – Primary Reference Time Clock (Phase/Time)• ePRTC – Enhanced Primary Reference Time Clock

(Phase/Time) – Clock combainer• BC – Boundary Clock Class A, B, C & D• TC – Transparent Clock

Equipment Clocks - Frequency

• Clocks for Frequency G.8262 Timing characteristics of Synchronous

Ethernet Equipment slave clock (EEC) G.8263 Timing Characteristics of Packet based

Equipment Clocks (PEC) and Packet based Service Clocks (PSC) G.8265.1 Precision time protocol telecom profile for

frequency synchronization.

Equipment Clocks – Time/Phase

• Clocks for Time/Phase G.8272 Primary Reference Timing Clock (PRTC)

specificationG.8272.1 enhanced Primary Reference Timing Clock

(ePRTC) specificationG.8273 Clock General Requirements G.8273.2 Telecom Boundary Clock specification G.8273.4 Timing characteristics of assisted partial timing

support slave clocks.

What is a PRTC (G.8272) ?

• PRTC is a function (not a “box”)• It specifies the performance (max|TE) of timing signal

from UTC to network interface (PTP output) • PRTC-A = +/-100nsec relative to UTC (specified 2012) • PRTC-B = +/-40nsec relative to UTC (value is

provisionally agreed 10-2017)

G.8272.1 ePRTC Functional Model

• Provides for highly accurate time of better than 30ns to UTC in combination with time reference

• Provides robust atomic-clock based time even during extended GNSS outages

• Long time constants can address diurnal effects such as those arising from variation in ionospheric delay of signals from GNSS satellites

“Autonomous primary reference clock” is a key component of the ePRTC

PRTC vs. ePRTC Time Accuracy and Stability

Time Error: <=100ns

MTIE

TDEV

PRTC Time Accuracy

Time StabilityMTIE is G.811 with 100 ns maximumTDEV is G.811 exactly

G.8272

G.8272.1

Time Error: <=30ns

ePRTC Time Accuracy

Time Stability

MTIE below G.8272 with 30 ns maximumTDEV below G.8272 and tau extended

MTIE

TDEV

G.8272.1 ePRTC Time Holdover

• ePRTC: Hold better that 100ns for 14 days of holdover “Class A” (PRTC time holdover not defined)

• ePRTC: Longer holdover under discussion “Class B” (100ns for 80 days under discussion)• ePRTC: The longer the holdover, the better the “autonomous primary reference” required

G.8273.2 High Performance BC Class C & DHigh accuracy (sub‐nano

second) optical time transferLayer 1 (lambda)  or Layer 0 

(physical) Optical Wave Division layer 

(WDM,DWDM or CWDM) Ciena, Cisco, Infinera

High Performance BCSingle Clock Domain

From client to master portsG.8273.2 

Class C & D (cTE < 10, Max|TE|low< 5 ns)

OCXO, Rb

Network RequirementsOptical Networks5G, eCPRI, cRAN

TE < +/‐130ns & beyond

Class A = 50nSClass B = 25nSClass C = 15nSClass D = 5nS

G.8275.x PTP telecom profiles

Profile Network Timing Support Transport Domain SyncE

G.8275.1 Full Path Multicast 24‐43 Must

G.8275.2 Partial Path Unicast 44‐63 Optional

PTP Telecom Profiles for Time and Phase synchronization – “Full Timing Support” (G.8275.1) – “Partial Timing Support” (G.8275.2)

PTP DISTRIBUTION NETWORK ARCHITECTURESDifferent architecture – Different performance – Different risk

GNSS Security for PNT Applications

GNSS sourcesGNSS sources

JAMMING, SPOOFING,WEATHER ANOMOLIES,ENVIRONMENT EFFECTS,SATELLITE ERRORS,GROUND STATIONMALFUNCTIONS,OTHERS…

POSITION

NAVIGATION

TIME

SecurePNT

Measurement, Monitoring,Analytics and Visualization

SecureSky

Reception

Atomic Clocks+

Timescale technology

VISIBILITY

DETECTION

RESILIENCY

GPS Spoofing and Jamming Vulnerabilities

• The vulnerability of GPS to interference is not a new phenomenon.

• GPS signals are extremely weak and highly vulnerable to jamming and spoofing resulting in partial or complete loss of GPS signal.

Microsemi BlueSKY GNSS Firewall

Current - Frequency PTP Deployments Typical Illustration

•Each GM has a local GPS•Each Chain considered an Island

•Low risk•Holdover duration 2 weeks

•Moderate Increase in dropped calls during handover between cells

GM

GM

GM

2G/3G/4G

2G/3G/4G

2G/3G/4G

Sync Quality NOT monitored

Simple Migration to Phase example

•Activate Phase at the eNB•While making no changes to the Timing source

•Assume backhaul supports Phase•Extreme High risk

•Holdover duration 15 minutes•Expected Large drop in Capacity , Bandwidth, Subscriber Numbers, Handover etc.

GM

GM

GM

4G/5G

4G/5G

4G/5G

Sync Quality NOT monitored

Simple Protection of Phase example – Protected

• Utilize another GM, deploy over the existing “MPLS” Network Backup PTP using APTS links to Aggregation Grand Masters

• Moderate risk• GM Holdover duration 1 week +

• Single backup Path

GM

GM

GM

5G

5G

5G

GM

Core Site ~10Km GM upgrade to support APTS required

Sync Quality monitored and Reported

PTP Using Assisted Partial Timing Support (APTS)

•APTS PRTC maybe placed at any point on the sync chain•It is expected that most deployment will be at points near to the eNB where the time error budget can be most easily controlled.

PRCFrequency ref

End Equipment

Time Slave Clock

T-SC

GNSS

Packet Network

PTP GM

PTP GM

• Customer A had a good IP network, carried over DWDM– Ran MPLS and syncE did not reach the edge.

• DWDM has large asymmetry– This example, had 27µS

APTS – Core Fed over DWDM Test

• APTS Calibrated the Path

• Provided splendid performance during 5 day test without GPS.

+/‐ 100nS Scale

Simple Protection of Phase – Absolute Accuracy

• Provide dedicated link between each site to make Timing Ring

• Time Quality is now Absolute• Removes all uncertainty of timing quality

• Low risk• Triple protected Phase input at each Aggregation Site.

GM

GM

GM

5G

5G

5G

GM

Same GM Hardware

Sync Quality monitored and Reported

Simple Protection of Phase – Protected with ePRTC

• Add one Caesium at any of the sites

• Share ePRTC with entire region• Provides Timing services, even with GNSS jamming or outage lasting “months”

• Lower risk• Triple backup Path • GNSS Independence

GM

GM

5G

GM

5G

5G

GM

Sync Quality monitored and Reported

Example Protected National Level

City 1

City 2

City 3

City 4

City 5

City 6

City 7

Sync Quality monitored and Reported Nationally

METRO AND NATIONAL PHASE DELIVERY ARCHITECTURE

Absolute accuracy with GNSS independence

High Accuracy Phase Delivery

•5g today requires 1.1uS , Future services will require much greater accuracy.

•GNSS can be expensive to deploy in Metro areas•Protection is needed from Jamming and Spoofing – city wide•ePRTC will provide long Holdover and better alignment to UTC

•Traditional PTP accuracy degrades when mixed with the voice and data traffic

High performance BC for “East-West” Use Case

Geographical RedundancyNo GNSS required in every location – Perfect for Urban

All Devices , are within 50nS of the original PRTC‐B

(Worst Case)

Precise Time from ePRTC or PRTC‐B at each end

Redundant time path for each 4100

Expansion of High Perf BC

Dedicated Dark Fibres, using Bi‐Di SFPFixed Offset is known and removed

Each 4100 is aligned within 5nS of its input

Separating Time from the Traffic ensures time has no variation or 

uncertainty  

GNSS for Monitoring Only 

The only way to engineer a sub 100nS Network with 

Redundancy 

BlueSKY

ePRTCePRTC

BlueSKY

Architecture Summary• Data networks are excellent at transporting data• When PTP is mixed with voice and Data.. The Time quality is unknown• Sync equipment embedded in Routers and Switches may have drawbacks

– Often change in performance with FW updates.– Often has very low quality oscillator

• Separation of Data and PTP is the only way to be sure of the timing quality• A solution where data and PTP are mixed, is very localised , has uncertainty

– No Network Engineering - More Grand Masters - 1µS solution only• A solution where data and PTP are separate , can be national and is predictable

– Some Network engineering – Fewer Grand Masters - <50nS solution

TP4100 HPBC

TimePictra Monitoring and Management

GPS Receiver

GPS Receiver

TP4100  ePRTC

TimeCesium

TimeProvider 5000

IGM Indoor

IGM Outdoor

GNSS Firewall

GNSS FirewallTimePictra