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Sync on TAP – Syncing infrastructure with software
Nov 2022
K Hann, senior director, R&D, Oscilloquartz, ADVA

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• Data center / general trends
• Motivation for synchronization with software
• Time Appliance Project
• O-RAN architecture
• Software (virtual) synchronization
• Options; results; interfaces
Agenda

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New role of Software in synchronization
Miniaturization
Consolidation
General trends Cloud trends
Scalability Explosive growth
(synchronization management)
Sustainability Open source (white box)
(efficiencies of scale)
Accuracy;
resiliency;
security

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Clocks - Hardware with “soul”
PPS or PTP
• HW timestamping of events
• Accuracy HW (~1ns)
• Accuracy SW (~1us)
• Huge vendor investment
Interface(s)
CPU
Application
(SW)
HW
clock
(PHC)
(RTC/PLL)
OS
Application
(SW)
`
...
...

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Existing clocks/applications use dedicated HW
Synchronization network management
Optical Cs ePRC+
NG GM/SSU
Magnetic PRC/ePRC
Access Edge Core
NG GM/SSU
device/network
Monitor
Front/backhaul
Core network
O-RAN/edge DC
TV
studio
Defense
comm
Aviation
radars
Data
center
Financial
trading
911 center
Smart power
grids
HP Optical Cs
Cesium

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Why?
Software synchronization

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Datacenters – open time server
= TimeCard + standard server + standard NIC
• Interconnect via PCIe (using PTM)
• Optional PPS connections (to ensure high accuracy)
TAP use case:

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M.2 slot is commonly available and allows smooth sync add on
OSA PCIe TimeCard with M.2 module as core
Core built as M.2
Sync Module
Concept Implementation

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O-RU based on white box server + NIC + Accelerator
High accuracy sync over PCIe
Telecoms - Open-RAN architecture

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HOW?
Software Synchronization

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White box server with SoftSync
Oscilloquartz solution
• HW timestamping NIC (Intel)
• SoftSync PTP client on host machine
• Synchronizes OS with system APIs
• Performance ~ 100ns (timestamping NIC)
Interface(s) NIC
CPU
Software
app
1
SoftSync
OS
Software
app
2
PPS or PTP
`

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SoftSync measurement using G.8265.1 master
Back to back

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White box server with PCIe / M.2 interface
• GNSS input
• Local Ethernet port (PTP)
• No offset between GNSS and Ethernet
• PCIe port
Interface PCIe
CPU
Software
app
1
OS
Software
app
2
GNSS
Local
Ethernet

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Precision time measurement
Synchronization over PCI-e (PTM)

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White box server with PCIe / M.2 interface
PTM on PCIe to improve performance
• PTM support on PCIe
• PCIe <-> CPU ~10ns
• CPU <-> OS ~ 1ns
• No offset between GNSS and Ethernet (PTP)
• Class C BC possible
• PTM available 2023
PCIe
CPU
Software
app
1
OS
Software
app
2
GNSS
Local
Ethernet
PTM

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Synchronization of virtualized applications, e.g., O-RAN
What other applications?
Infrastructure synchronized by SW
PCIe
CPU
Application
2
O-RU
PCIe
CPU
Application
1
O-DU
Ethernet Ethernet
PTM
PTM
PTP
TGPIO TGPIO

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Conclusions
1) Highest accuracy applications require dedicated HW
2) Sync on COTs server (TAP; O-RAN)
• Available today ~100ns (e.g., SoftSync)
• PTM enables ~10ns accuracy (also for virtualized SW)
• PCIe = Timing interface
3) M.2 Sync Module = small footprint PCI-e

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Thank you
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