#CiscoLive
Synchronizing 5G
Mobile Networks
Network Based Timing
Shahid Ajmeri, Sr. Product Manager, Provider Connectivity Group
BRKSPG-3050
#CiscoLive
Cisco Webex App
Questions?
Use Cisco Webex App to chat
with the speaker after the session
How
1
Find this session in the Cisco Live Mobile App
2
Click “Join the Discussion”
3
Install the Webex App or go directly to the Webex space
4
Enter messages/questions in the Webex space
Enter your personal notes here
Webex spaces will be moderated
by the speaker until June 9, 2023.
https://ciscolive.ciscoevents.com/ciscolivebot/#BRKSPG-3050
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
3
Disclaimer:
Use of the terms “master” and “slave” in this
presentation is ONLY in association with the
official terminology used in industry
specifications and standards (for example
IEEE1588, ITU-T SG15/Q13 specifications,
eCPRI, ORAN-Alliance and so forth), and in
no way diminishes Cisco’s commitment to
promote diversity, equity, and inclusion.
We will be sharing our efforts to remove this
language from our products, content and
culture at Cisco.
If at any point you feel uncomfortable,
please feel free to exit the session for a
couple of minutes and then rejoin. You can
also reach out to us directly with questions,
or requests for more information on our
approach in a format that works for you.
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
4
Key Abbreviations
APTS
Assisted Partial Timing Support
O-DU
Open Distributed Unit
(a)BMCA
(alternate) Best Master Clock Algorithm
O-RU
CA
Carrier Aggregation
PRTC
Open Radio Unit
Primary Reference Time Clock
CoMP
PTP
cTE
Coordinated Multi-point
Constant Time Error
dTE
Dynamic Time Error
SyncE
EEC
Ethernet Equipment Clock
T-BC
Synchronous Ethernet
Telecom Boundary Clock
eEEC
Enhanced EEC
T-GM
Telecom Grand Master
ESMC
Ethernet Synchronization Message Channel
T-TC
Telecom Transparent Clock
eSyncE
T-TSC
FTS
Enhanced SyncE
Full Time Support
Telecom Time Slave Clock
Time Alignment Error
GNSS
Global Navigation Satellite System
TDEV
MITM
Man in the Middle
TE
MTIE
Maximum Time Interval Error
TSN
O-CU
Open Centralized Unit
UTC
PTS
TAE
#CiscoLive
BRKSPG-3050
Precision Time Protocol
Partial Time Support
Time Deviation
Time Error
Time Sensitive Networking
Universal Coordinated Time
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
5
Agenda
•
Introduction
•
New Concepts and Technologies
•
Redundancy, Resiliency and Monitoring
•
PTP Security in 5G RAN
•
Design Guidelines
•
Summary
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
6
Drivers of Precision Timing
Emergencies
Location Accuracy
Positioning
Correlation
AR/VR/MR, V2V,
Drones, Aviation,
Advertising
Behavior and Event analysis
IT Operations,
Monitoring, Log analysis
Syntonization
Ensuring two nodes are
synchronized on correct
rate or frequency
Control
Behavior and Event analysis
Sensor data processing
Efficiency
Emergency response,
Tracking, Defense
Security / Trust
Event Detection
Predict Future Events
Improve Bandwidth
Channel Processing, KPIs
4G LTE / 5G Radios
WiFI6 / WiFi 7
AI/ML Machines
Avoid Casualties
Proving when event
happened.
Detection and Response
IOT, Smart Cities,
Education, Healthcare
TDM, Optical Networks
Precision and Traceability
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
7
Time Synchronization across Architectures
Performance Measurement /
Service Assurance
Cable Network
Timing
xHaul
Network Timing
DOCSIS
DU/CU
RPD
SR PM for accurate latency
measurement
Pre-Agg
/ Agg
RPD
RPD
Residential
Wholesale Providers
Timing
3rd Party / Metro Links
APTS
Feature
Backup Timing
DU/CU
GPON
DOCSIS
Pre-Agg / Agg
Timing as a Service
RPD
RPD
OLT
OLT
APTS: Assisted Partial Timing Support
Public or Private 5G
Metro Transport
#CiscoLive
BRKSPG-3050
Cable / GPON Transport
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
8
Time Synchronization in 5G Networks
Cell Synchronization Requirements
• Transmitter power ON/OF
• Change Transmit / Receive modes
• Air propagation time
etc.
TDD
TAE 3µs
Coordinated Transmission and Reception
Increase throughput with Carrier Aggregation, Dual
connectivity
• Improve performance with coordinate multipoint operation
etc.
•
TX Diversity / NB-IoT
TAE <65ns
Frequency
Band A
Frequency
Band B
Intra Band Contiguous
<130ns FR2, LTE
<260ns FR1
Frequency
Band A
Frequency
Band B
Intra Band Non-Contiguous
<260ns (FR2, LTE)
3us (FR1)
Frequency
Band A
Frequency
Band B
Inter Band CA
<260ns (LTE)
3us (NR)
Application Requirements
Positioning and Tracking
Time-sensitive networking: Robot control or Autonomous
Vehicles
• Extended Reality
etc.
•
•
Positioning
TAE <100ns
3GPP TS 36.104, 38.104
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
TAE : Time Alignment Error
#CiscoLive
9
Timing Distribution in Radio Access Network
GNSS per Cell Site
PRTC/T-GM
Network Based Timing
PRTC/T-GM
PRTC/T-GM
T-BC
Transport
Network
T-BC
Transport
Network
PRTC: Primary Reference Timing Clock, T-GM: Timing Grand Master, T-BC: Telecom Boundary Clock, GNSS: Global Navigation Satellite System
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
10
Deployment Options
T-BC
G.8275.1
Full Path Support
T-BC
PTP Aware
Network
T-BC
PTP Aware
Network
PTP Aware
Network
PRTC / T-GM
T-BC-P / T-TSC-P
T-BC-P
G.8275.2
Partial Timing Support
PTP Unaware
Network
PTP Aware
Network
PTP Unaware
Network
PRTC / T-GM
PRTC
Assisted
Timing
T-BC-P
Assisted
Partial Timing Support
PTP Unaware
Network
PTP Aware
Network
PTP Unaware
Network
PRTC / T-GM
T-BC-A / T-TSC-A
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
11
5G Synchronization Requirements
Requirement 1:
Absolute Time
At Network level:
• Phase Accuracy: 1.1 µs
• Frequency Accuracy: 16pbb
1
2
3
N
a
1
2
3
N
b
Max|TE| < 1.5µs for entire chain
b1
Nb
Requirement 2:
Relative Time
At Air interface
Phase: TAE 3µs
Frequency: 50pbb
b2
b3
a1
1
2
N
3
a2
Time Error accumulation up to node N
Max|TE| < 1.5µs for entire chain
PRTC/T-GM
T-BC
Max |TE| < 260ns
Inside
synchronization
Cluster
Na
Nc
c1
c2
Relative Air Interface
TAE within cluster
130ns / 260ns
c3
T-TSC / gNB
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
12
ORAN Fronthaul Architecture Options
C1
C2
Transport
Network
O-DU
Network Timing/SyncE
Backup
Transport
Network
Dark Fiber O-RU
O-DU
Network Timing/SyncE
Backup
Timing / SyncE
O-RU
Fronthaul
Timing / SyncE
C4
C3
Timing / SyncE
Transport
Network
Transport
Network
O-DU
Fronthaul
O-DU
O-RU
Network Timing/SyncE
Backup
Network Timing/SyncE
Backup
#CiscoLive
BRKSPG-3050
Fronthaul
O-RU
Timing / SyncE
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
13
Time Budget Example : ORAN C3 Architecture
A/B
C
O-DU
PRTC/T-GM
O-RU
T-BC
T-TSC
T-BC
T-TSC O-RU
Transport
Network
Relative Air Interface TAE
within cluster
260ns
Fronthaul
T-BC
T-BC
Network Timing/SyncE
Backup
PRTC/T-GM to O-DU
 1.1µs
1) Time Error at Radio
Relative Time Budget on Fronthaul Transport
100ns to 190ns
2) Time Error at UNI of O-RU
3) Relative Time-budget on transport
a) Error at Radio Elements
|TERE| = 20ns
O-RU |maxTE| = |TERE| + T-TSC |TE|
260ns – 2 x O-RU |maxTE|
b) Regular O-RU with Class B T-TSC
T-TSC |maxTE| = cTE + dTE = 60ns
a) Regular O-RU = 80ns
a) For Regular O-RU
260ns – 2x80 = 100ns i.e.  50ns per link
b) enhanced O-RU = 35ns
b) enhanced O-RU
260ns – 2x35 = 190ns i.e.  95ns per link
c) enhanced O-RU with Class C T-TSC
T-TSC |maxTE| = 15ns
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
14
Type of Clocks and Network Budget
T-BC “1”
PRTC-A  100ns
PRTC-B  40ns
ePRTC
 20ns
Link
Asymmetric
Compensation
 380ns
 590ns
 10ns
T-BC “n”
 20ns
Random
Network
Variations
 10ns
 200ns
D
C
G.8271.1 Network Reference Points
A/B
Class B
T-BC “21”
21 nodes
Short Term
Holdover
 20ns
 10ns
 250ns
 150ns
End Application
Class C
21 nodes
 1.1µs Network Budget
 30ns
 1.5µs End-to-End Budget
T-BC / T-TSC / T-TC
cTE
dTE (MTIE)
Max |TE|
dTE (high pass filter)
Class A (with SyncE)
 50ns
40ns
100ns
70ns
Class B (with SyncE)
 20ns
40ns
70ns
70ns
Class C (with eSyncE)
 10ns
10ns
30ns (T-BC)
Under study for T-TC
Under Study
Class D (with eSyncE)
*no T-TC
Under Study
Under Study
5 ns (low pass) *
Under Study
* Measured with first order filter of 0.1Hz
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
15
Recommended Approach for 5G
Network Based Timing
GNSS per Cell Site
Centralized PRTC provide better solution to meet relative time-error
•
In theory, PRTC-A receivers at cell site will not meet relative time budget, PRTC-B or
ePRTC may help.
•
Network node with Class C T-BC performance are required.
200ns error from PRTC alone
+100ns
Provide better Resiliency and Redundancy
-100ns
PRTC/T-GM
BMCA algorithms for best master selection
Virtual port: for GNSS receiver redundancy
Assisted Partial Timing support (APTS), with backup PTP, for better accuracy and holdover
on partial timing aware networks
and so forth
•
•
•
PRTC/T-GM
Transport
Network
Better antenna installations with clear satellite visibility
Reduced cost
•
•
Less antenna and PRTC/GNSS installations
Better operations
BMCA: Best Master Clock Algorithm
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
16
New Concepts
and Technologies
To meet 5G Synchronization Requirements
GNSS Receiver Performance
Impacting Factors
Ionosphere
Transmission
delays and Errors
Troposphere
Ionospheric
transmission
delays and errors
•
•
•
Satellite visibility
Antenna siting
Cable delay
correction
•
•
#CiscoLive
Multi-path
Interference
(from other
sources)
BRKSPG-3050
Correction data
available to the
algorithm
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
18
Ionosphere Errors
L1
Ionosphere
L1
L1
Single Band
Antenna
Antenna
Cable
PRTC-A
GNSS =  100ns
The biggest source of time error in PRTC-A receivers is
disturbed signal propagation through the ionosphere
which:
Solar activity is expected to be much higher
in next 4 years, which will impact PRTC-A
performance
• Has 24 hours diurnal cycle depending on the rotation
of earth, with minimum delay at night.
• Depends on space weather, resulting from changes
in solar activity (11-year cycle)
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
19
PRTC-A Performance
Not going to be accurate enough for 5G services
Illegal Jammers
Antenna installation are not always
in open skies.
Satellite visibility is limited in
built-up areas
Solar activity is expected to
be more active, local and
instantaneous errors could
impact GNSS receiver
#CiscoLive
BRKSPG-3050
Off the shelf
Jammers
Single band limits antijamming / anti-spoofing
capabilities
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
20
PRTC-B Receivers
Necessary to meet 5G requirements
L1
L2
L1
L2
L1
L2
Ionosphere
Dual Band
Antenna
Antenna
Cable
PRTC-B
GNSS = 40ns
Stability
•
PRTC-B receivers are Dual-band receivers
•
Measures ionospheric anomalies and models
these effects better to improves overall stability
of the clock
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
21
✓ Multi-band support for better accuracy
• Improves traceability to UTC accuracy
✓ Better security against Anti-Jamming and
Anti-Spoofing attacks
✓ Improves overall network time-budget
requirements
PRTC-B Benefits
Cisco Solution
• 8000 Series platforms
✓ Addresses “Relative Time Budget” within
cluster of radios
✓ Helps meet stringent position tracking and
location accuracy across Private 5G and
Public 5G deployments
• Public 5G:
•
Carrier Aggregation, Dual Connectivity, CoMP
•
TSN, Power Grid, Factory Automation,
Robotics, Drone
• Enterprise:
• Metaverse:
•
AR / VR use cases
• AI / ML and Analytics
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
22
eSyncE / eEEC (G.8262.1)
Mandatory for Class C Clocks and 5G RAN
• 5x improvement to frequency
synchronization performance
Stability
EEC (G.8262)
eEEC (G.8262.1)
Wander Generation
MTIE: 40ns @ 0.1s
TDEV: 3.2ns @ 0.1s
MTIE: 7ns @ 0.1s
TDEV: 0.64ns @ 0.1s
Noise Transfer
Filtering
EEC (G.8262)
eEEC (G.8262.1)
Clock Bandwidth
1-10 Hz
1-3 Hz
Holdover
EEC (G.8262)
eEEC (G.8262.1)
Short term phase
Transient Response
@ Const Temp
120 ns at Initial step
10 ns at Initial step
Initial response to loss of
sync reference
50 ns/sec frequency offset,
plus 1.16 X 10-4 ns/s2 drift
10 ns/sec frequency offset,
plus 1.16 X 10-4 ns/s2 drift
• Better phase/time synchronization
performance for SyncE-assisted PTP
• Improved time noise transfer
performance
• Phase jump due to noise transfer from
SyncE to PTP is low-pass filtered
• Improved holdover performance
• Longer chain or stable performance for
long time @ 1.5us performance
MTIE: Maximum Time Interval Error, TDEV: Time Deviation
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
23
ESMC and Enhanced ESMC (G.8264)
Enhanced ESMC Include new TLVs
containing:
•
•
•
•
QL
Which Quality I should use?
PRC
Originator Clock-id
New SSM Codes
SyncE steps removed from nearest SSU/PRC
eSyncE steps removed from nearest SSU/PRC
QL
PRTC
QL
Improves Solution:
1. Allow higher accuracy clocks
2. Separate counts of EEC/SEC and eEEC/eSEC hops
from originator source
3. Traceability and Monitoring
4. Identify the source node
• Detect Timing Loops
ESMC: Ethernet Synchronization Message Channel
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
24
ESMC and Enhanced ESMC (G.8264)
2. New flags helps in traceability:
1. New Hop Counters for EEC and eEEC clocks
clockIdentity : Node1
Count of EEC clocks: 0
Count of eEEC clocks: 1
Mixed EEC/eEEC: No
Partial chain bit: No
1
clockIdentity : Node1
Count of EEC clocks: 0
Count of eEEC clocks: 2
Mixed EEC/eEEC: No
Partial chain bit: No
2
•
•
•
Do all nodes in the chain support eSyncE?
Do all nodes in the chain support eESMC?
Was the TLV generated in the middle of the chain?
clockIdentity : Node1
Count of EEC clocks: 0
Count of eEEC clocks: 3
Mixed EEC/eEEC: No
Partial chain bit: No
3
clockIdentity : Node1
Count of EEC clocks: 0
Count of eEEC clocks: 4
Mixed EEC/eEEC: No
Partial chain bit: No
4
Flags:
5
Extended QL TLV
Is chain mix of SyncE and eSyncE = 0 = NO
The chain has non eESMC nodes = 0 = NO
clockIdentity : Node1
Count of EEC clocks: 0
Count of eEEC clocks: 5
Mixed EEC/eEEC: No
Partial chain bit: No
Original QL TLV
eEEC and eESMC
EEC and eESMC
EEC and ESMC
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
25
ESMC and Enhanced ESMC (G.8264)
2. New flags helps in traceability:
1. New Hop Counters for EEC and eEEC clocks
clockIdentity : Node1
Count of EEC clocks: 0
Count of eEEC clocks: 1
Mixed EEC/eEEC: No
Partial chain bit: No
1
clockIdentity : Node1
Count of EEC clocks: 0
Count of eEEC clocks: 2
Mixed EEC/eEEC: No
Partial chain bit: No
2
•
•
•
Do all nodes in the chain support eSyncE?
Do all nodes in the chain support eESMC?
Was the TLV generated in the middle of the chain?
clockIdentity : Node1
Count of EEC clocks: 1
Count of eEEC clocks: 2
Mixed EEC/eEEC: Yes
Partial chain bit: No
clockIdentity : Node1
Count of EEC clocks: 1
Count of eEEC clocks: 3
Mixed EEC/eEEC: Yes
Partial chain bit: No
4
3
clockIdentity : Node1
Count of EEC clocks: 1
Count of eEEC clocks: 4
Mixed EEC/eEEC: Yes
Partial chain bit: No
5
EEC and eESMC
Flags:
Extended QL TLV
Is chain mix of SyncE and eSyncE = 1 = YES
The chain has non eESMC nodes = 0 = NO
Original QL TLV
eEEC and eESMC
EEC and eESMC
EEC and ESMC
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
26
ESMC and Enhanced ESMC (G.8264)
2. New flags helps in traceability:
1. New Hop Counters for EEC and eEEC clocks
clockIdentity : Node1
Count of EEC clocks: 0
Count of eEEC clocks: 1
Mixed EEC/eEEC: No
Partial chain bit: No
1
clockIdentity : Node1
Count of EEC clocks: 0
Count of eEEC clocks: 2
Mixed EEC/eEEC: No
Partial chain bit: No
2
•
•
•
Do all nodes in the chain support eSyncE?
Do all nodes in the chain support eESMC?
Was the TLV generated in the middle of the chain?
clockIdentity : Node4
Count of EEC clocks: 1
Count of eEEC clocks: 1
Mixed EEC/eEEC: Yes
Partial chain bit: Yes
No Extended TLV
3
4
clockIdentity : Node4
Count of EEC clocks: 1
Count of eEEC clocks: 2
Mixed EEC/eEEC: Yes
Partial chain bit: Yes
5
ESMC, EEC
Flags:
Extended QL TLV
Is chain mix of SyncE and eSyncE = 1 = YES
The chain has non eESMC nodes = 1 = YES
Original QL TLV
eEEC and eESMC
EEC and eESMC
EEC and ESMC
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
27
✓ eSyncE is mandatory for Class C timing
eSyncE and
eESMC
✓ eSyncE provides better performance,
stability and holdover to the clock
✓ Enhanced ESMC improves operations
• Avoid SyncE loops
• Provides hop counts
• improves traceability and Monitoring
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
28
Compute Based Timing
Most popular outdoor deployments are
C1 architecture
Linux PTP Project Status Check:
•
Profile configuration is static
•
•
•
Limited or no support for Remote Management
•
•
•
S-plane monitoring
Phc2sys and ts2phc state monitoring
Operations / Non-compliance
•
•
•
Cisco
NCS540
•
Linux PTP Project – Timing NIC
•
•
•
•
Any change require service restart
Impacts radio operations
•
•
•
ptp4L: Synchronize clock using PTP protocol
ts2phc: Synchronize clock to external signal e.g. 1PPS
phc2sys: synchronize NIC clock to system clock
pmc: PTP management client
#CiscoLive
Not fully compliant to ITU-T G.8275.1/G.8275.2
Not compliant to G.8264 and G.781
Doesn't comply to ORAN WG4 Specification
• Test Cases Section 3.3 on S-plane compliance
ptp4l uses s0/s1/s2/s3 status instead of “locked”,
“hold over”, “freerun”
• Doesn't update status in “announce” messages
No Support for Primary to Backup switching
No Support for profile interworking
No support for APTS or Virtual Port – no resiliency or
redundancy for timing
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
29
✓ Industry needs to focus on contributing
and improving Linux PTP project
Compute Based
Timing
✓ For 5G architecture, network-based
timing provide most advanced solution
✓ Network-based timing could help reduce
complexity and cost on compute
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
30
Redundancy,
Resiliency and
Monitoring
Redundancy for Grand Master
Use Case: Relative Timing within Radio Cluster, Fronthaul and Private 5G
Requirement:
•
Set of RUs connected to a common DU
•
All radios and DUs need to be synchronized
by common PRTC for better accuracy and to
manage relative timing within cluster
•
T-GM
200ns error
from PRTC
alone
O-DU
T-GM
Seamless network failover in case of
PRTC failure
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
32
Redundancy for Grand Master
Approach - Virtual Port (VP)
•
Note: T-GM can only distribute clock (all ports are master ports), can not receiver it.
But T-BC can.
•
Virtual Port (G.8275.2 Annex B) provides electrical frequency and phase inputs to T-BC
•
Virtual Port gives flexibility to configure node as ”boundary clock” and run BMCA to
select best time source – Local GNSS or remote grandmaster
GNSS
GNSS
VP
VP
S
BC
Router A
Router A has better clock quality
M
Router B runs BMCA and selects
router A as primary clock
#CiscoLive
BRKSPG-3050
S
S
BC
Router B
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
33
Redundancy for Grand Master
Use cases: Relative Timing within Radio Cluster, Fronthaul and Private 5G
Solution:
Primary
•
•
Configure Primary and Secondary PRTC
priority
Configure each node as T-BC with VP
(virtual port) to select priority for local vs
remote GNSS
•
Primary PRTC distributes clock to all nodes
– O-RUs, Routers, O-DUs
•
In case of Primary PRTC failure, BMCA will
auto select secondary PRTC
T-BC
with VP
Common
clock source
for all Radios
within a
cluster
Secondary
O-DU
T-BC
with VP
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
34
Resiliency with backup PTP
Use Case: Last mile over 3rd party links
O-DU
G.8275.2
Requirement:
G.8275.2
•
Set of RUs connected over 3rd party links / 3rd
party network that doesn’t support timing
3rd Party
Transport
#CiscoLive
BRKSPG-3050
PTP un-aware network
doesn't guarantee timing
performance
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
35
Resiliency with backup PTP
Approach: Assisted Partial Timing Support (APTS)
•
APTS function allows T-BC to select local GNSS as the primary source; and
continuously measures the time offset compared to that recovered from the back up
PTP signal.
•
In case of GNSS failure, T-BC will failover to back up PTP and removes the observed
offset to maintain time accuracy during GNSS failure.
•
APTS configuration requires Virtual Port (G.8275 Annex B) support
GNSS
Measure offset from backup PTP clock.
In case of local GNSS failure, maintain
clock accuracy with backup signal
VP
S
BC
Router A
M
S
Backup PTP from remote router
#CiscoLive
BRKSPG-3050
BC
Router B
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
36
Resiliency with backup PTP
Use Case: Last mile over 3rd party links
O-DU
G.8275.2
Solution:
•
Connect local GNSS at each site to accurately
synchronize Radios
•
Use back up PTP (G.8275.2) from network to
maintain performance during local GNSS failure
•
When local GNSS is down, accuracy and stability of
the clock depends on PTP clock quality
G.8275.2
PTP as backup
3rd Party
Transport
#CiscoLive
APTS
BRKSPG-3050
APTS
APTS
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
37
ATPS Deployment Guidelines
The clock locks to the PTP reference, and the dTE
is larger, and cTE could be also larger, due to
the asymmetry caused by PTP unaware network.
Although the clock can compensate it in advance,
some remaining cTE could be still present.
Time Error (ns)
The clock is in holdover
within a short time,
decided by BMCA algorithm
Lock to local GNSS
Lock to local GNSS
•
APTS is considered mainly for
“Partial timing aware network”
•
Backup Timing should be available as
part of G.8275.2 profile
G.8275.2 over partial aware network
is not reliable. Please ensure
G.8275.2 quality is good, to get max
benefits of APTS
•
Avoid multi-profile with APTS
22 ns (transient for switching & residual PTP cTE) +
•
15 ns (tranfser PTP gain) +
X ns (generation XO PTP dTE)
•
Time
Local GNSS is lost, clock
goes into holdover and
generates a first transient
The clock selects the PTP
reference, and changes from
holdover to lock, and
generates a second transient
APTS can correct STATIC time error,
dynamic error is still un-controlled
•
Only good for last measurement
GPS is restored and selected
by the clock
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
38
Holdover with SyncE Assistance
Use Case: Longer holdover
•
Holdover is either oscillator only, or assisted with external frequency (SyncE)
•
Staying within 1.1 µs is only possible for several hours when relying on local oscillator
Loss of
SyncE
Zero ns
Realigned
1.1 µs
Loss of
PTP
(11 mins)
5 Hours
Reacquired
10 Hours
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
39
Network Monitoring for Improved Resiliency
Monitoring Alternate Master Time Information
•
Allows PTP monitoring of alternate path
•
Calculates PTP offset between PTP
received from primary path and
alternate link
•
If offset crosses define threshold,
monitoring alarm is generated
•
•
This alarm doesn’t trigger BMCA
The functionality helps monitors
network health
•
Fiber asymmetry between links,
network failures and so forth
Use Case 1:
Passive port monitoring
Master port
Use Case 2:
Master port monitoring
Passive Port
ITU-T G.8275.1 Annex G
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
40
✓ VP is for timing redundancy
• PRTC Redundancy
• G.8275.1 based full path support networks
✓ APTS is for better timing resiliency
Redundancy,
Resiliency and
Monitoring
• Local GNSS for timing accuracy
• Backup PTP for maintain performance during
GNSS failure
✓ Holdover with SyncE assistance
• Improves overall performance
✓ Cisco Solution support mature PTP
monitoring and management solution
• SNMP MIBs:
•
•
•
CISCO-PTP-MIB
CISCO-NETSYNC-MIB
CISCO-GNSS-MIB
• Yang / Telemetry Support
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
41
PTP Security
in 5G RAN
Timing Security Attacks
Attack
Impact
Attacker Type
Internal
False Time
Accuracy
degradation
External
DOS
MITM
Packet Injector
Changing Clock
Parameters
X
X
Spoofing
X
X
X
Replay Attack
X
X
X
Rogue Master Attack
X
X
X
Changing and removing
Messages
Packet Delay Manipulation
X
X
X
MITM
X
X
X
X
Packet Injector
DOS attacks
X
X
X
X
X
Cryptography
Performance attacks
X
X
X
X
X
X
X
X
X
GPS Spoofing / Jamming
X
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
43
MACsec and Security for Timing
• MACsec is a L2 port-based security mechanism
•
Either encryption + integrity checking OR only integrity checking (IEEE 802.1AE)
•
Maybe mechanisms to choose whether to send secured/unsecured on a port
• Either asymmetry or dynamic time error can arise through:
•
Difference in time to encrypt/decrypt messages
•
Selection of receive/transmission timestamping point
•
Differences in time to encrypt/decrypt subsequent messages
MAC
DA
MAC
SA
SEC
Tag
Ether
-type
Payload
ICV
FCS
MAC
DA
Encrypted Data
MAC
SA
Ethertype
Payload
FCS
Original Packet
Integrity Protected
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
44
PTP over MACSec Deployment Challenges
PTP
PHY detects PTP
packet and
Provides
Timestamp for
“Follow Up”
message”
MACSec
PHY
Timestamp is
ideally done when
packet hits wire –
at PHY.
PTP
MACSec
PHY
1-Step Clock
2-Step Clock
• PHY based time-stamping doesn’t work for
1-step clocks
• Timestamp can be generated by measuring “Sync”
packet delay at the egress, and sub-sequent “Follow
Up” message can carry it.
• Timestamp can not be inserted into the “Sync”
packet before it goes through the MACSec
• Encryption must always take same number of cycles
(even after key rollover); any jitter can impact PTP
performance.
• PHY will not be able to differentiate encrypted PTP
packets with other packets
• On receive side, decryption should take same time as
encryption to avoid PDV from asymmetry
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
45
PTP over IPSec Deployment Challenges
PTP over IPSec
• IPSec is end-to-end and introduces additional delay.
PTP
• IPSec Engine could be 1) Hardware based or 2) Software based
a. Hardware based IPSec Engine
IPSec Engine
PHY
Egress
Ingress
•
Challenges are similar to MACSec
b. Software Based IPSec Engine
•
Time-stamping in software increases delay variations
•
Hardware based timestamping requires further considerations
•
Ingress packets has to be stored until corresponding PTP messages
are decrypted and timestamped
•
Outgoing packets should follow 2-step method
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
46
Architectural Approach
PTPoMACSec
T-BC
PTPoMACSec
T-BC
PTPoMACSec
T-BC
• MACSec performs best with Full Path Support
(FPS) and ITU-T G.8275.1 profile
• IPSec is end to end (Client to Server) and doesn’t
align with G.8275.1 profile.
T-BC
PTPoMACSec
PTP unaware network
T-BC
• 5G timing requirements can not be met when
PTP over MACSec is deployed on Partial Timing
Support (PTS) networks with ITU-T G.8275.2
PTPoIPSec
T-BC
T-BC
T-BC
• IPSec is end to end - doesn’t meet 5G
performance requirement
• Underlay network has no visibility to PTP packets
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
47
Security Mechanisms Guidelines
IEEE 1588-2019 Annex P
•
Prong A: PTP integrated security using TLVs
•
Prong B: External Security Mechanisms
•
L2 with MACSec i.e. Hop by hop
•
L3 with IPSec i.e. End to End
•
Prong C: Architecture Guidance
•
Prong D: Monitoring and Management Guidance
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
48
•
PTP Security
Status
•
MACSec
•
MACSec with ClearTag is being
discussed, however it doesn’t solve all
issues.
•
Inter-op will be biggest challenge
IPSec
•
•
Not suitable to meet 5G RAN timing
requirements
Industry is aligning towards supporting
•
IEEE 1588-2019 prong A: PTP integrated
security using TLV
•
Key Exchange and Processing
mechanisms to be finalized
•
@ ITU-T - “Further Study”
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
49
Design Guidelines
Network Design
Phase Synchronization
•
•
•
•
•
•
Deploy G.8275.1 with physical frequency (SyncE/eSyncE)
Reduce PDV (boundary clocks reset PDV back to zero)
Reduce asymmetry (routing, link, node, transport) - boundary clocks limit asymmetry
Likely requires remediation of transport layer
Avoid “PTP over Loopback” or ”PTP over un-numbered” interfaces
Deploy G.8275.1 in transport with bundle interfaces, avoid G.8275.2
Frequency Synchronization
•
•
•
•
If possible, use physical distribution (SyncE/eSyncE) not packet for frequency
G.8265.1 interoperates with SONET/SDH & SyncE (some gaps with eESMC mapping)
Packet distribution goal: reduce PDV (minimize hops as it disallows aware nodes)
Asymmetry isn’t an issue for frequency over packet
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
51
Select the Correct Profile…
Feature
G.8275.1 PTPoE
G.8275.2 PTPoIP
Transport
Layer 2 Multicast
Layer 3 (IP) Unicast
Network Model
Full on-path support
Partial on-path support
IP Routing
Not applicable
Problematic (rings, asymmetry)
Transit traffic
Not allowed
Problematic (jitter, asymmetry)
Performance
Best
Variable
Configuration Model
Physical Port
L3 device
PTP over Bundles
No issue
Being worked on (for BC’s)
Asymmetry
Reduced (T-BC on every node)
T-BC good, not T-BC = bad
PDV/jitter
Timestamping on wire (small)
T-BC good, not T-BC = bad
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
52
Remediating Optical Transport
• “Smart” optical devices introduce buffering and/or complex processing
• Optical systems: separate channel for PTP (like Optical Service Channel)
• Cisco solution based on the NCS2K
* Bi-directional fiber reduces asymmetry
T-BC
T-BC
PRTC / T-GM
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
53
Summary
1.
2.
Key Take-a-ways
Network based Time Synchronization
is un-avoidable in 5G RAN
•
Reduce compute complexity and cost
•
Provides Resiliency and Redundancy
Advanced features matures 5G
Synchronization
•
Class C Clock, PRTC-B Receivers
•
eSyncE, eESMC
•
VP and APTS
3.
PTP Security is not mature yet
4.
Follow Design Best Practices for
predictive timing performance.
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
55
Further
Information
“Synchronizing 5G Mobile
Networks”
•
Publisher: Pearsons/Cisco Press
•
eBook & Print
•
Published: June 2021
https://www.ciscopress.com/store/
synchronizing-5g-mobilenetworks-9780136836254
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
56
5G Timing & Synchronization
•
Resources: Past
Cisco Live
Sessions
BRKSPG-3050 Synchronizing 5G
Mobile Networks
Event: 2023 Amsterdam
•
BRKSPM-3295 5G Timing &
Synchronization architectures
Event: 2020 Barcelona
•
BRKSPG-2557 5G Synchronization Design, Testing and Deploying Timing to
support 5G rollouts
Event: 2020 Barcelona
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
57
Recommended
Sessions on 5G
Cisco Private 5G Learning Map
Start
June 4 | 2:00 pm
June 5 | 11:00 am
June 7 | 4:00 pm
New Adventures in Wireless: The Journey
of WiFi6 and Private 5G Networks for the
Enterprise
Is your Enterprise Network Ready for P5G
Monolithic or Polylithic packet cores?
The case for specialized use-casebased mobile packet cores
TECSPG-2432
BRKSPG-3004
BRKENS-2950
June 5, | 8:00 am
June 5 | 11:30 am
Architecting Enterprise Security in a Wi-Fi
plus Private 5G World
Leading Your Digital Transformation with
Cisco Private 5G Network Offer
BRKSEC-2085
June 5 | 8:30 am
BRKSPG-2042
Architecting Private 5G for resiliency,
security, and enterprise network
convergence
June 5 | 10:30 am
BRKSPM-1006
The 5G System as a Spectrum
Management Solution
PSOSPG-1002
June 8 | 09:30 am
BRKSPG-2044
5G Use Cases Flight Line of the
Future and Smart Warehouse
June 6 | 3:00 pm
June 8 | 01:00 pm
WiFi6 and Private 5G for the
Enterprise – a ‘Better Together’
Journey
Getting Started with Private 5G
PSOGEN-1033
BRKGEN-2001
BRKEWN-2030
IBOSPG-2007
June 7 | 2:30 pm
June 8 | 1:00 pm
Unlock business outcomes from
connectivity with a Private 5G solution
Cisco P5G - A Robust and Secure
Architecture
Finish
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
59
Cisco 5G Learning Map
Start
June 4 | 9:00 am
June 5 | 2:30 pm
June 6 | 2:30 pm
Designing IoT Wireless Networks
Don’t Just Connect, Grow your IoT
Business with Cisco IoT Cellular
Connectivity Management
5G Transport Design Considerations
Combining Onsite and Cloud-Based
Deployments
TECIOT-2584
June 5, | 8:30 am
BRKNWT-2203
Automation-first Approach to Network
Infrastructure Modernization for 5G &
Beyond
BRKSPG-1002
IBOSPM-2030
June 5 | 3:00 pm
June 6 | 4:00 pm
BRKIOT-1126
Connecting Moving Assets with Cisco IoT
Solutions
June 6 | 10:30 am
Design, Deploy and Manage Transport
Slicing using SDN Controller and Assurance
Cloud-Ready Converged SDN Transport
BRKSPG-2133
BRKSPG-2315
June 5 | 1:00 pm
June 6 | 1:00 pm
Hiking the Band Canyon with 5G: New Use
Cases, New Business Outcomes
Cisco Secure Edge Protection – Protecting the
5G Edge against DDoS Attacks
BRKARC-2094
BRKSPG-2401
#CiscoLive
BRKSPG-3050
Holistic Security in 5G Deployments
June 7 | 10:30 am
June 5 | 1:00 pm
BRKSPG-2063
BRKSPM-2027
Evolution of the Transport Network
Architecture in the Context of 5G and
Open RAN
June 8 | 8:30 am
BRKSPG-3050
Synchronizing 5G Mobile Networks
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
60
Cisco 5G Learning Map
June 8 | 9:30 am
IBOSPG-2006
DISH Wireless, World’s first 5G
Network with a Hybrid Cloud
June 8 | 10:30 am
BRKNWT-2301
DevNetOps Automation Approach to
Network Infrastructure Modernization for 5G
and Beyond
June 8, | 11:00 am
BRKSPG-2040
Troubleshooting 5G Architectures
June 8 | 1:00 pm
BRKMER-2001
Postcards from the 5G Edge: Meraki
Cellular Gateways
Finish
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
61
Reference:
Inclusion and
Diversity
IF-1002 Learn how Inclusive Language Can
Positively Impact your Business @ Panel
Discussion
DEVLIT-2761 Automating Language Bias
out of Code
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
62
Fill out your session surveys!
Attendees who fill out a minimum of four session
surveys and the overall event survey will get
Cisco Live-branded socks (while supplies last)!
Attendees will also earn 100 points in the
Cisco Live Game for every survey completed.
These points help you get on the leaderboard and increase your chances of winning daily and grand prizes
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
63
Continue
your education
•
Visit the Cisco Showcase
for related demos
•
Book your one-on-one
Meet the Engineer meeting
•
Attend the interactive education
with DevNet, Capture the Flag,
and Walk-in Labs
•
Visit the On-Demand Library
for more sessions at
www.CiscoLive.com/on-demand
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
64
Thank you
#CiscoLive
Gamify your Cisco Live experience!
Get points for attending this session!
How:
1 Open the Cisco Events App.
2 Click on 'Cisco Live Challenge’ in the side menu.
3 Click on View Your Badges at the top.
4 Click the + at the bottom of the screen and scan the QR code:
#CiscoLive
BRKSPG-3050
© 2023 Cisco and/or its affiliates. All rights reserved. Cisco Public
66
#CiscoLive