1. Pedro Moreira CERN BE-CO-HT
1/31/2018
Pedro Moreira
CERN
BE-CO-HT
White Rabbit

2. White Rabbit Agenda Requirements White Rabbit Protocol IEEE 1588 (PTP)
1/31/2018
White Rabbit
Agenda
Requirements
White Rabbit Protocol
IEEE 1588 (PTP)
White Rabbit Control Message Protocol (WRCMP)
Q&A

3. White Rabbit Requirements
1/31/2018
White Rabbit
Requirements
Synchronize up to 2000 stations with sub-nanosecond accuracy (jitter < 100ps)
Bidirectional links
Timing and Data Traffic
3 layers based protocol (Physical, Data Link, Network)

4. White Rabbit - Overview
1/31/2018
White Rabbit - Overview
White Rabbit
OSI MODEL
Application
Not
Specified
PowerLink ?
LXI ?
Presentation
EtherCat ?
Session
Transport
Network
PTP | WRCMP
DataLink
White Rabbit
MAC WR
Specification
Physical
Synchronous
Ethernet

5. White Rabbit – Network Topology
1/31/2018
White Rabbit – Network Topology
Timing Traffic
Data Traffic
White Rabbit Network
Timing Receiver
WR Switch
. . .
White Rabbit
Master
GPS

6. White Rabbit – The Protocol
Its is the set of (layer 2) standard rules for data representation, signaling and error detection required to send information over the Ethernet channel.
Objectives
To tailor Ethernet to be used as real-time communications network
Keep it Simple, Stupit!

7. White Rabbit – The Protocol
The Ethernet Frame
The Medium Access Control (MAC)
CSMA/CD (not used in switched Ethernet)
Problem
High Latency

8. White RABBIT – The protocol
High Priority Packet (HP)
Ethertype: 0xA0A0
Higher priority
Critical control messages
Fixed low latency
Standard Priority Packet (SP)
Ethertype: 0xA0A1
Lower priority than HP same as standard Ethernet traffic
Non-critical control messages (management, diagnostic)

9. White RABBIT – The protocol
High Priority Packet (HP)
Preemption
If there is a frame being transmitted the node stops its transmission, store the frame, and start the transmission of the incoming HP packet.
Fix Latency

10. White RABBIT – The protocol
High Priority Packet (HP)
For further discussions ( Layer 2+ issues)

11. White RABBIT – The protocol
Standard Priority Packet (SP)
For further discussions ( Layer 2+ issues)

12. White RABBIT – IEEE 1588 IEEE 1588 - Precise Time Protocol (PTP)
Standard for time distribution over package based networks
Present benchmarks
1μs for topologies with no more than 30 consecutive slaves
IEEE AS
Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks
Standard for IEEE 1558 over Ethernet for Audio, Video Broadcast
One of the AVB (Audio Video Bridging) standards, IEEE 802.1AS, specifies the distribution of precise timing and synchronization over the AVB network. The requirements of IEEE 802.1AS will allow the media timing for each respective A/V application to meet its jitter, wander, and time synchronization requirements with appropriate filtering at the endpoints.

13. White RABBIT – IEEE 1588 IEEE 1588 - Precise Time Protocol (PTP)
White Rabbit Master/Slave – Ordinary Clocks
White Rabbit Switch – Boundary Clock
No Transparent Clocks
The use of synchrounous ethernet reduces the phase noise accumulated in the cascades clocks

14. White RABBIT – IEEE 1588
Synchronization

15. White RABBIT – IEEE 1588 PTP Header Correction Field : Resolution:
152 fs.
Max Value
2 s
Used for transparent clocks to calculate the travelling time in the transparent clocks.
In White Rabbit it‘s used for phase and link delay compensation
It doen‘t break the standard does it?

16. White Rabbit – IEEE 1588 Delay Model Device (White Rabbit master)
slave)
PHY
SFP TX RX
SFP
PHY RX TX

17. WHITE RABBIT – WRCMP WRCMP – White Rabbit Control Message Protocol
WR network configuration/diagnostic
Connection of WR node
Sends WRCMP INVITE
Receives WRCMP INVITE RESPONSE
Setup the PTP Daemon
Connection of non-WR PTP node
Sends WRCMP INVITE msg
Timeout for WRCMP INVITE RESPONSE
Setup PTP Daemon for non-white rabbit node
PTP configuration
Sends WRCMP_PTPCONF
Interval sync
Phase Interval
WR management and network control

18. WHITE RABBIT
Thank You ! Q&A
Thank you Q&A