Presentation: Time synchronization is one of the key imperatives of communications infrastructure. Real time persistence and near real time data processing are becoming essential to serve enhanced user experience in many industries. In this presentation, Dhiman Chowdhury will present sync plane design constructs for time aware non-deterministic networks across industry verticals. Note: This presenation was shared at Open Compute Project (OCP) Time Appliance Project (TAP). About Dhiman: Dhiman Deb Chowdhury manages Product Management and Strategic Marketing for Protempis (formerly Trimble’s Time and Frequency division). Prior to joining Trimble, Dhiman served as vice President of Product Marketing redefining edge networking and open networking and expanding IPI global presence. At Delta Electronics, Dhiman was instrumental to whitebox products and technology venture “Agema System''. He advocated open networking, network cloudification and whitebox solutions for different industry verticals as a thought leader. In this role, Dhiman oversaw the technology strategy and development of Agema open networking product solutions. Prior to joining Delta Electronics, Inc., Dhiman worked as Director of Technical Program (R&D) at Allied Telesis, Inc where defined and developed technology strategy, products and services for enterprise and service providers networks. In 2004, he spearheaded the development of Industry’s first residential VoIP gateway at Netgear where he started service provider product lines. Prior to this, he was a member of Nortel’s technology leadership team working as a principal architect to define protocol, product and technology. At Nortel, Dhiman participated in the development of Industry’s first hybrid VoIP Routing Systems. Dhiman has authored several technology books and written many scholarly articles. His recent publication “Nextgen Network Synchronization” provides a comprehensive overview of sync plane design for various network infrastructure and applications across industry verticals. Subsequently, some of his technology books on Unified and high-speed internetworking are continued to be reference handbooks for undergraduate studies globally. Dhiman studied Doctor of Business Administration (DBA) at The Robert Gordon University (RGU) and MBA at University of Liverpool. Dhiman is an avid blogger on technology and a Philanthropist.

1. Connect. Collaborate. Accelerate.
NextGen
Network
Synchronization
Protempis
(formerlyTrimbleTiming & Frequency Division)
Dhiman D Chowdhury

2. Connect. Collaborate. Accelerate.
Brand Announcement
TrimbleTiming and Frequency Division is now
Protempis
www.protempis.com

3. Connect. Collaborate. Accelerate.
Precise Time Synchronization is essential in
mission critical applications
< 1.5µS < 250µS
Factory Automation
& Mission Control
< 20 µS
SmartGrid
Fault Protection
5G Edge
Infrastructure, CBRS
& Private LTE Data
Center
Intercell URLLC
Applications
± .5µS
Smart Industry, Healthcare,
Entertainment,Transport, Energy, Mfg
Sub µS to Sub mS
MachineVision
Autonomous
Vehicle

4. Connect. Collaborate. Accelerate.
Understanding How Network
environment are becoming more
deterministic
• Time Aware Non-deterministic Network: The network withTime
components (e.g. NTP, PTP) but lacksTransport guarantee. Protocol
such asTCP provides some form of transport receipt information but
no guarantee.
• Deterministic Networks: Time and GuaranteedTransport, e.g.
Industrial Networks. IEEE DefinesTSN specifications for deterministic
Networks.
In-time best effort On-time Guaranteed Transport

5. Connect. Collaborate. Accelerate.
Time Error Budget consideration for
the synchronization of Time Aware
Non-Deterministic Network
• Device level Clock Drift: Clock Drift is measured inTE (Time
Error) budget. AT-GM should be <100ns andT-BC <50 ns in
TE.
• Packet DelayVariation (PDV): Due to queuing mechanism,
networking gear may induce significant PDVs. A non PTP
aware switch may induce more than 180 ns in PDV.
• AccumulatedTime Error: It is measured at device level with
TE of incoming port and outgoing port.
• Link Asymmetries: AllTE includingTE induced by cables and
PHYs etc.

6. Connect. Collaborate. Accelerate.
Network are changing from monolithic to
microservice and the challenge is how to
provide precise sync at container level
2015
NOS
Separation of
HW and SW
Open Networking
2017
NOS
Controller/
Orchestrator
Software Defined
Networking (SDN)
2018
Router/
Switch
Router/
Switch
Network Device
VNF
Network Function
Virtualization (NFV)
Network
Virtualization
2019
Server
RAN and BBU
Functions
OpenRAN
2020
Server
kubernetes
VNFs
Microservice
architecture
Cloud Native
Note:Virtualization is defacto for NextGenTelecom Networks

7. Connect. Collaborate. Accelerate.
Guaranteeing end-to-end time requires
identifying and mitigating sources of Time
error in the networks
T-GM T-BC T-BC T-BC
End device or
application
T-TSC
Time Error Generation
<100 ns
[G.8272]
DynamicTime Error (dTE)
<20 ns perT-BC
ConstantTime Error (cTE)
<50 ns perT-BC (typeA)
<20 ns perT-BC (type B)
cTE generated at link chain
Noise generated by
end application
[ITU-T defines telecom base
station application to be
measured <150ns]
Ref: G.8271/Y.1366.1

8. Connect. Collaborate. Accelerate.
PTP provides better time accuracy and
in path sync correction over NTP
NTP PTP
Industry de-facto and used in public
networks since antiquity
Relatively new, most appropriate for LAN and WANs
Traditionally hierarchical design but
today’s NTP grand master supports direct
connectivity to slave
Less hierarchical design, Slave can connect to any
clock source whether Grand master or Boundary
Clock.
Sync Accuracy is milliseconds to seconds Sync accuracy from 10s of nanoseconds to
microseconds.
NTP lacks on path support PTP provides support through Boundary and
Transparent Clock
Software based and non-deterministic
delays contribute to timing inaccuracy
PTP support hardware timestamping and Assisted
PatialTiming (APTS).

9. Connect. Collaborate. Accelerate.
Real time and near real time traffic in data center
environment requires microsecond level end -to-end
accuracy to prevent operational failure
Edge
Computing
Edge
Computing
Smart
Grid
Connected
Cars
Smart
Factory
Connected
Applications
Connected
Oil Platform
Connected
Rail
Connected
Transportation
Smart City
Data Center
Mobile
Networks
Connected
Wind Turbine
Macro/Small Cells
Macro/Small Cells
Time Synchronization

10. Connect. Collaborate. Accelerate.
A combination of Openservers, grandmaster
and boundary clock guarantee localized time
accuracy
Time-sensitive Application POD Non-real Time Application POD
PTP
Slave
GM200 as T-BC
TOR TOR
WAN/DCI
Border
Leaf
Real-time
Big
Data
Analytics
Non-real
time
Application
Fabric Switch
Time Synchronization
GM 200
as GM
Software
base PTP
GM200
as BC
TS200
NTP Server
NTP
Clients
NTP
Clients
TOR
OpenTime Server
TAPTime Card
NvidiaConnect6
DX with PPS
PPS input

11. Connect. Collaborate. Accelerate.
Precise Synchronization is an essential
Network design element for both private or
public wireless networks
Private Wireless
Public Networks
End to End Synchronization
T-GM
T-GM
T-GM

12. Connect. Collaborate. Accelerate.
ITU-T suggest end-to-end time error
budget of 1.5 µs for Wireless
Fronthaul Network
GM
1 2 3 4 5 6b 7b
Sync
Cluster
< 260 ns
Sync Supply chain for
all Base stations
T-BC
max hop 5
6c 7c
8b
9
6a 7a 8a
Max < 1.5 µs (preferred <1.1 µs)
T-TSC
T-TSC
T-TSC
T-BC
T-BC
Base Station cooperating Cluster
Note: A standard Mobile network must maintain
end to end time error budget of <1.1 micros seconds.

13. Connect. Collaborate. Accelerate.
Precise Sync is common for four
different variants of Private/
Public Wireless Networks
CBRS/ Midband
Spectrum Sharing
Cloud Native 5G
OpenRAN
Legacy
PreciseTime Synchronization

14. Connect. Collaborate. Accelerate.
A combination of Boundary and Grandmaster
deployment helps achieve 1.1 µs at Fronthaul
Edge Cloud MPLS Core
IXP
Core
Router
PE
Internet
Data Centers
Aggregation
C-RAN
ROE
GM200
CSR/
DCSG
DCSG/
CSR
Transit
T-BC
T-BC
T-BC
PRTC-B ePTRC
Co-ordinated PRTC
Bullet™ 360
GNSSAntenna
Bullet™ 360
GNSSAntenna GM200
T-GM
BBU
Hoteling
CellSite Router (CSR) implements boundary clock, Radio
unit can use local clock source and sync with boundary
clock (T-BC).
RU CSR Edge Cloud
T-BC
T-TSC
1.1µs

15. Connect. Collaborate. Accelerate.
Hybrid 4G/5G Macro cell deployments
require precise sync at the edge
CU
EPC
T-GM
Max node = 3
CSR/
DCSG
DU
DU
RU
RU
FTU
FTU
RU
• FTU (Fiber Transceiver Unit)
• DU (Distribution Unit)
• RU (Radio Unit)
• CU (Central Unit)
RU
GM 200
Coordinated
PRTC
GM 200 as
standaloneT-BC
Embedded
or standalone
GM 200 as
standaloneT-BC
if CSR lacksT-BC
Bullet™ 360
GNSSAntenna
Bullet™ 360
GNSSAntenna
Note: Protempis can provide embedded or
Standalone sync solutions for RU, DU and CSR
1.1µs

16. Connect. Collaborate. Accelerate.
There are four paths to achieving
synchronization in OpenRAN
1. Config LLS-C1: Network Timing
Distribution from O-DU to O-RU
2. Config LLS-C2: Network timing
distribution from O-DU to O-RU
in a switched Network
3. Config LLS-C3: Fronthaul switch as clock
source for network timing distribution
4. Config LLS-C4: Local PRTC in O-RU and O-
DU and no PTP for time distributions

17. Connect. Collaborate. Accelerate.
Config LLS-C1: Network Timing
Distribution from O-DU to O-RU
DU
(Distributed Unit)
CU
(Central Unit)
Radio Unit (RU)
eCPRI/ ROE F1 Interface
Ethernet
SyncE/1PPS
SyncE/PPS
EPC/Core
High Phy
O-RAN 7.2x
Ethernet
GNSS Timing Module
Trimble
ICM 360 or 720
Embedded Slave Clock
Trimble GM310
Embedded Boundary Clock
or Grand Master
PTP (IEEE 1588)
Standalone Boundary
or Grandmaster Clock
GM200
GM310
Point to Point Link between O-RU and O-DU.
Clock source is O-DU

18. Connect. Collaborate. Accelerate.
Config LLS-C2: Network timing distribution
from O-DU to O-RU in a switched Network
DU
(Distributed Unit)
CU
(Central Unit)
Radio Unit (RU)
eCPRI F1 Interface
Ethernet
SyncE/1PPS
SyncE/PPS
EPC/Core
High Phy
O-RAN 7.2x
Ethernet
GNSS Timing Module
Trimble
ICM 360 or 720
Embedded Slave Clock
Boundary Clock
or Grand Master
PTP (IEEE 1588)
GM200
CSR/DCSG or
PTP Unaware Switch
RU
One or more switch between O-RU and
O-DU. Switches can be PTP aware or
unaware. Clock source is O-DU.

19. Connect. Collaborate. Accelerate.
Config LLS-C3: Fronthaul switch as clock
source for network timing distribution
DU
(Distributed Unit)
CU
(Central Unit)
Radio Unit (RU)
eCPRI
F1 Interface
Ethernet
SyncE/1PPS
SyncE/PPS
EPC/Core
High Phy
O-RAN 7.2x
Ethernet
GNSS Timing Module
ICM 360 or 720
Embedded Slave Clock
Embedded Ordinary Clock
PTP (IEEE 1588)
Trimble GM200
GM310
CSR/DCSG
RU
Grand Master
Clock
One or more fronthaul switch between
O-RU and O-DU. Clock source is Fronthaul
Switch.

20. Connect. Collaborate. Accelerate.
Config LLS-C4: Local PRTC in O-RU and O-DU
and no PTP for time distributions
DU
(Distributed Unit)
CU
(Central Unit)
Radio Unit (RU)
eCPRI/ ROE F1 Interface
Ethernet
SyncE/PPS
EPC/Core
High Phy
O-RAN 7.2x
Ethernet
Local PRTC
No PTP is required
Disciplined Clock
Point to Point link between O-RU and O-DU.
No IEEE1588, clock source local PRTC.
SyncE/PPS

21. Connect. Collaborate. Accelerate.
All 5G deployments including mid-band spectrums
require precise sync since 5G spectrum is TDD
100 GHz
6 GHz
1GHz
Mid band High Band
24GHz
TDD
Low
Band
3.5 GHZ
3.5 GHz 3.7GHz 4.2 GHz
CBRS
C-Band
150 MHz
5G Spectrum
2.3 2.4 GHz
Licensed Shared
Access (LSA)
66 GHz
mmWave band
Band-48

22. Connect. Collaborate. Accelerate.
GNSS Antenna
GM200
as T-GM
GM200 as T-BC
PTP-unaware
Switch
PTP-unaware
Switch
Neutral
Host
SAS
EPC
MNO
GM200 providing optimal sync
solutions for CBRS type midband
spectrum sharing Enteprise 5G
deployments
GM200
as T-BC
PTP-unaware
Switch
LSA OAM
CBRS Deployment for Enterprise 5G requires precise
Sync due to the use of midband spectrum

23. Connect. Collaborate. Accelerate.
Telecom Cloud uses precise sync at the
edge for optimal network operations
Central DC
Edge DC
Far Edge DC
1000’s ± 50 2
Virtual RAN,
Virtual DU &VirtualCU
MEC apps & virtual
gateway functions
Virtual Mobile
network management
functions
Per Metro Region
GM200 as
T-BC
ICM 360 or RES
720
1.1µs

24. Connect. Collaborate. Accelerate.
Cloud Native Enterprise 5G uses precise
sync for optimal processing of voice and
time sensitive data traffic
MEC (Multi-access
EdgeComputing)
5GCVNFs
Enterprise On-Premise
5G
gNBs
5G
gNBs
Kubernetes
Servers
UPFs
MEC (Multi-access
EdgeComputing)
5GCVNFs
Enterprise On-Premise Mobile
Network
Operator
GM200
GM200
Timing
Modules
TrimbleTiming
Modules
GM200
RES720
RES720

25. Connect. Collaborate. Accelerate.
Industrial Networks uses precise time
synchronization to efficiently operate and prevent
catastrophic failure of automated equipment
PLC
Transport
5G Access
Edge DC
(Industrial App, cloud,
3rd party apps, functions)
PLC
PublicCloud
Factory A
Factory B
GM200 GM200
Timing
Module
Timing
Module

26. Connect. Collaborate. Accelerate.
Protempis Portfolio for GNSS sync
Source selection

27. Connect. Collaborate. Accelerate.
Protempis Time Server Portfolio

28. Connect. Collaborate. Accelerate.
Thank You

29. Connect. Collaborate. Accelerate.
Reference Slide
• cTE (defined by ITU-T G.8260) are immune to filters for example,
asymmetry in the transmission medium between network elements,
asymmetries within network elements, the beating effect in near-
synchronous time-stamping, and so on. Ref: G.8271/Y.1366.1 section
IV.2
• The dynamicTE component, dTE(t), is related to random noise
accumulation (e.g., due toT-BC time-stamping or wander accumulated
in the synchronous Ethernet network and injected into the time
synchronization plane when synchronous Ethernet is used in
combination with PTP or due to packet-delay variation experienced by
the timing signal packets).