How Smooth Are Your Packets?

Transcription

1 How Smooth Are Your Packets? Implementation Realities and Best Practices of IP and PTP 4 DECEMBER 2018 Karl J. Kuhn Sr. Applications Engineer karl.j.kuhn@tektronix.com

2 Don t Worry- It s Digital- It Just Works!!! Analog Degrades Gracefully It Tells You All Its Aches and Pains Window into Electronic World Drifts Over Time Analog Can Work When Very Impaired You Decide Digital Has Cliff Effect It Tells You Nothing Digital is Analog but Digital Decides Baseline Intensive Care Ward EVERYONE Has This All Figured Out Interoperability All Devices are Guilty Big Circuit Board Testing is Too Expensive 2 2

3 High Level Testing Concepts- Analog vs Digital Quality of Service (QoS) Perhaps Totally Transparent to End User Luma Chroma Audio Levels Bandwidth Transmission Latency Jitter and Wander Quality of Experience (QoE) The End User Will Notice and The Phone Will Ring Long Access Times Buffer Wait Times Black Frames Freeze Frames Blockiness Slice Errors Loudness and Level Issues Closed Captioning 3 3

4 Why do we still use SDI? IP MIGRATION SDI works very well indeed Plug and Play Bit perfect pictures High Availability Extremely low latency and jitter Frame accurate switching is inherently simple A unidirectional thin protocol that is extremely easy to deploy SDI is an open, non-proprietary and universally supported standard

5 Why are we moving to IP? IP MIGRATION Born IP Delivered IP Reduce the total system cost COTS (Commercial Off-the Shelf) products Less number of cables, Lighter truck Prepare for the future Multi format support Reconfigure the system easily without replacing most equipment Ubiquitous Accessibility Cloud operation

6 MERGING TOGETHER: IT AND BROADCAST ENGINEERING Black Burst Tri Level and SDI is last holdout Video Engineer SDI, Analog, Audio Black Burst and Tri Level Sync Importance of delivering signal quality QoS centric methodology SDI vs IP IP is an Abstraction Challenge in understanding the IT technology IT Engineer IP Flow, Protocol, Network traffic, Configuration NTP and PTP Less sensitive to the impact to the quality from a bit error Data can be reset- not the case with Video QoE centric mythology Challenge in understanding the video technology Need Reporting Monitoring and Analysis tools for QoS and QoE in hybrid facilities 6

7 SDI Video Plant 7

8 IP Video Plant 8

9 Low-Jitter on Video over IP IP packets carrying video Perfect Stream Point to Point Jitter is low Time 9

10 Higher-Jitter on Video over IP Everyone Sharing the Same Pipe Time 10

11 Video IP Roadmap ST SDI Encapsulation over IP ST AES 67 - AES audio Encapsulation over IP IEEE1588 > ST 2059 PTP Precision Time Protocol IS-04 AMW A NMOS ST Image Data Meta Data RFC 4175 IETF RTP ANC VSF TR-04 VSF TR-03 ST ,20,30,40 11

12 Hitless Switchover ST Switches use IGMP Clean Switch Using Frame Numbers Sender Receiver Stream Sender A x x Duplicate Stream Generic Switch Packet Selection 1 2 3

13 Basics of ST2110 We finally get to get rid of blanking! 13

14 Basics of ST2110 ST2110 defines a set of streams that are transported individually, but may be timed together. 14

15 Basics of ST2110 This means we can have a separate audio stream, separate video stream and separate ancillary stream. They may or may not be on the same wire. Session Description Protocol (SDP) files keep them together- for RTP, SDP files as our manifest. Senders expose an SDP file that describes the location of the Sender s RTP stream. Note: other information in this SDP file is also used by the In-stream Identity and Timing Specification, which includes example SDP files. 15

16 Basics of ST basic definitions : system timing : video : video distribution in time (timing model) : audio : support for legacy AES3 (in progress) : Ancillary data : ST with AES67 audio and ST2059-1/2 for timing (in progress) 16

17 Synchronization Accuracy Accuracy traditionally is based the smallest element of the video Analog Video (NTSC) approx. 800 picoseconds one degree of Subcarrier Digital Video (SDI) Within a pixel 13.5 nanosecond for HD Rates PTP time accuracy between two slave devices to master within 1μs Accuracy enough to align the datagrams IP SRC IP DST RTP Header w/ TimeStamp Video Payload ST2110

18 ST 2110 Timing Reference Clock PTP 2110 Enabled Device Zero Offset Internal Clock Zero Offset Video Datagram Audio Datagram RTP Timestamp DECEMBER

19 PTP Network Primary Network Transparent Switches Boundary Switches Backup Network

20 Redundant System, Air-Gapped Network 1 Network 2 Spine Spine Spine Spine Leaf Leaf Leaf Leaf Leaf Leaf Client Client Client Client Client Client 20

21 Redundant System, Cross Connected Network 1 Network 2 Spine Spine Spine Spine Leaf Leaf Leaf Leaf Leaf Leaf Client Client Client Client Client Client 21

22 PTP Spine Leaf Network Primary PTP Master Backup PTP Master PTP BC Leaf PTP only PTP BC Leaf Network 1 Network 2 Spine Spine Spine Spine Leaf, BC Leaf, BC Leaf, BC Leaf, BC Leaf, BC Leaf, BC Client Client Client Client Client Client 22

23 First Step to Troubleshooting PTP VERIFY THE SETTING OF THE GRANDMASTER (GM) Setting of all the slave clocks need to match the setting of the GM Domain Domain is defined a number from 0 to 127 Profile General Profile send Sync commands.5persec AES Profile send Sync commands 1per Sec SMPTE Profile send Sync commands 8 per Sec Communication Mode Multicast, Unicast SMPTE Mixed Mode 4 DECEMBER

24 Verify PTP Domain YOU NEED TO KNOW THE DOMAIN YOU ARE TROUBLESHOOTING Domain is defined by a number from 0 to 127 Verify all devices are in the correct PTP Domain (0 to 127) In order for Devices to share PTP commands they need to be in the same Domain Each Domain will have a Grandmaster Clock Note: If you do not know what the Domain Check your GM settings or Capture a Pcap File of the Stream with the Prism or WireShark. Each PTP IP packet will have the Domain value. PTP Status 4 DECEMBER WireShark

25 Verify PTP Profile PROFILES HAVE DIFFERENT ANNOUNCE AND SYNC INTERVAL The three Profiles use in Broadcasting are: General Profile send Sync commands 1perSec AES Profile sends Sync commands 4 per Sec SMPTE Profile sends Sync commands 8 per Sec There are other differences between the Profiles SMPTE has a mixed communication mode Mixed Mode uses both Multicast and Unicast PTP Status 4 DECEMBER

26 Verify Sync Messages Rates (THIS CAN SHOW NETWORK ISSUES DROPPING THESE MESSAGES COULD CAUSE LOCKUP PROBLEMS) Active Fields Counts number of messages per Sec. Active Fields 4 DECEMBER 2018 Prism s IP Session Display / PTP Tab

27 Verify Switches Support Multicast PTP USES A DEFAULT MULTICAST ADDRESS ( ) PTP aware device should automatically join the PTP Multicast Announce, Delay-Respone,& Follow-UP messages uses port 320 Sync & Delay-Request messages uses port 319 Port 319 carries the time sensitive messages Prism IP Status Display show the two ports used by PTP SPG8000a PTP Status 4 DECEMBER

28 Verify the PTP Grand Master(GM) BEST MASTER CLOCK ALGORITHM (BMCA) DETERMINES THE GM Master based on several parameters that are carried by the Announce Priority 1 (Default Value 128) Lowest value wins (Range 0-255) Use to exclude devices from being Clock Class able to be the GM Clock Accuracy Clock Variance Priority 2 (Default Value 128) Lowest value wins (Range 0-255) Use to designate user default GM Final tie breaker Denotes quality of GM Lock Clock ID usually MAC address Verify Master ID Matches desired GM BMCA Values from the GM IP Session Display / PTP Tab 4 DECEMBER

29 Verifying Video Lock in the IP world JUST LIKE BASEBAND VIDEO YOU NEED THE SIGNALS TO SYNCHRONIZED TO A COMMON REFERENCE PTP Timing Display 4 DECEMBER

30 PTP Graphing 4 DECEMBER

31 RTP Sequence error / CRC error NEED MULTILAYER TROUBLESHOOTING METHODOLOGY Isolate the root cause of CRC error An error in IP layer causes RTP Sequence Error and CRC Error An error in SDI layer causes CRC Error Only 4 DECEMBER

32 ST Traffic Shaping and Delivery Timing 4 DECEMBER

33 ST Traffic Shaping and Delivery Timing 4 DECEMBER

34 ST Stream Timing 4 DECEMBER

35 ST Stream Timing 4 DECEMBER

36 ST Stream Timing 4 DECEMBER

37 ST DECEMBER

38 PIT Histogram ST DECEMBER

39 ST DECEMBER

40 Test Equipment Justification Process Where Do We Start? Continuous Learning Stay Current Get Management Buy In Elevator Pitch Fight for Budget Line Item Current Wish List Persistence!!!!!!! 12/4/ OF 24

41 Test Equipment Justification Process What is the Cost of Not Testing? UNKNOWN UNKNOWNS Quality Impacts and Rework Not Meeting Delivery Specification Missed Schedules and Budgets Advertising Revenue Legal Contract Issues Life and Death Truck Roll, Churn, Customer Service Issues Unknown Good/Bad Parts Sitting on Shelf REAL COST When Something Goes Wrong 12/4/ OF 24

42 Test Equipment Justification Process Speaking to Management Management Might be Non Technical/Non Creative Management by Spreadsheet Speak in Business Terms Cost Cutting/Saving Money- ROI Make Their Pain Go Away Cost of Not Testing Write an Easy to Understand Justification When Test Equipment Saved the Day Share the Good News Once You Acquire Gear USE IT Make sure Management Sees You Using Test Equipment Read the Manual In your Weekly/Monthly Report Tell How Gear Saved the Day 12/4/ OF 24

43 Test Equipment Justification Process Understand Why-What-Where You Need to Test Analog Video and Audio SDI and IP Video and Audio Compressed Content File Based Content RF and/or GigE Transport of Content Referenced Human Vision System Based Video Evaluation Unreferenced Video Quality of Experience ALWAYS HAVE A WISH LIST READY 12/4/ OF 24

44 Test Equipment Justification Process How You Benefit on a Personal Level Build Self Confidence Pro Active not Re Active Less Stress Reduce Finger Pointing Less Wasted Time Increase YOUR WORTH to the organization Stay Employed Enhance Your Resume 12/4/ OF 24

45 How Smooth Are Your Packets? Implementation Realities and Best Practices of IP and PTP 4 DECEMBER 2018 Karl J. Kuhn Sr. Applications Engineer karl.j.kuhn@tektronix.com

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