PTP Update 1588 Switches Why Adopt IEEE1588 u

PTP Update & 1588 Switches

Why Adopt IEEE-1588 u High accuracy time and frequency transfer via Ethernet u Saves money § Synchronization uses same channel as data (Ethernet) § No additional cable for timing (i. e. no coax or twisted pair) § Common media type – Cat 5 cable or fiber – Ethernet infrastructure u 2 of 54 Represents the future of accurate synchronization in an Ethernet centric world

Refresher: Packet Delays NTP Timestamp location NTP UDP IP IP Ethernet PTP Timestamp location Receive queue Transmit queue Network 3 of 54 NTP OSI Stack Timing packet

1588 vs NTP vs IRIG Perspective 4 of 54 IEEE-1588 NTP IRIG Peak time transfer error >100 ns >1 ms 10 ms Network type LAN Dedicated coaxial cables Spatial extent A few subnets LAN/WAN 1 mile over coax Error Source Switches & port contention with data Routers & O/S stack delay Cable delay

How Precision is Possible u Message Exchange Technique § Periodic Sync messages broadcast master to slaves (every 2 seconds by default) § Occasional delay measurement slaves to master u Hardware-Assisted Time Stamping § Time stamp leading edge of IEEE-1588 messages at network interface – Time stamp hardware required at master and slaves – Time stamp on send and receive – Removes indeterminate host operating system stack delays § Symmetricom proprietary algorithms use the precise time stamps to steer the oscillator for maximum precision 5 of 54

Understanding Slave Sync Accuracy is best defined as “it depends”… u Switches between the Master and Slave reduce synchronization accuracy by way of: § Packet arrival Jitter at switches and the Slave § Network Latency during packet transfer u Each network element contributes delays defined in terms of mean offsets with standard deviations Switch #1 Error 6 of 54 + Switch #2 Error = Combined Error

Clock Error By Network Element - No Traffic Boundary Clock and Transparent Clock performance not expected to change with traffic load 7 of 54

Switch Characteristics u COTS Switches introduce network timing jitter and diminishes PTP accuracy. § Jitter is induced whenever two packets compete for the same egress port. u 8 of 54 1588 enabled switches minimize switch induced network packet jitter.

Why Transparent Clocks (Switches)

Indeterminate Switch Delay Master Clock Time Slave Clock Time Sync message t 1 Switch Sync message Follow_Up message containing value of t 1 Data at Slave Clock t 2 t 1, t 2 Delay_Req message t 3 m t 2 t 3 t 1, t 2, t 3 t 4 Delay_Resp message containing value of t 4 time 10 of 54 t 1, t 2, t 3, t 4 Client Time = (T 4 – T 3) + (T 1 – T 2) Offset 2

Switch Delay & Transparency u Delay inside switch varies packet to packet § Transparent Clock (switch) measures the switch delay associated with the Sync Packet using hardware time stamping u Switch modifies the t 1 time stamp in the Follow-Up packet by adding the measured switch delay § 11 of 54 time sync packet left switch – time sync packet arrived at switch = Sync Packet delay inside switch Step 1 Variable packet delay in switch (measured per Sync packet) Sync Packet tdepart – tarrive = delay Step 2 Follow-Up Packet t 1 unmodified Modify time in Follow-Up Packet to account for Sync Packet delay Follow-Up Packet t 1 modified = t 1 unmodified + delay

COTS & 1588 Enabled Switches with Data Traffic Synchronization Error vs. Elapsed Time Error (microseconds) COTS Switch vs. 1588 Switch 12 of 54 40 20 COTS Switch 0 -20 -40 0 No Traffic 5 10 5 Mbps TFTP Traffic 15 20 25 30 35 40 40 20 1588 Switch 0 No Traffic 5 Mbps TFTP Traffic -20 -40 0 5 10 15 20 25 Elapsed Time (k*seconds) 30

Previewing the…

Sync. Switch TC 100 IEEE-1588 Transparent Clock

Sync. Switch TC 100 u It’s an Ethernet switch with IEEE-1588 transparency a. k. a IEEE-1588 v 1 Compliant Transparent Clock u Three (3) Models: § 8 x 10/100 Base. T ports § 6 x 10/100 Base. T ports 2 x Multi mode fiber § 6 x 10/100 Base. T ports 2 x Single mode fiber 15 of 54

Key Sync. Switch TC 100 Features u Industry firsts. . § 1 U Rack mounted TC § AC powered TC u IEEE-1588 v 1 Transparency § IEEE-1588 v 2 support comes later u u u Copper or copper/fiber mix of ports GUI interface for custom configuration Basic configuration operates as a regular switch (plug & play!) Prototype Sync. Switch 16 of 54

Advanced Features u Simple Network Management Protocol (SNMP) § Custom MIB u IGMP Snooping § Forward multicast traffic only to the hosts interested in that traffic. u VLAN § A VLAN has the same attributes as a physical LAN, but it allows for end stations to be grouped together even if they are not located on the same LAN segment. u Supports network ring topology § Rapid Spanning Tree Protocol (RSTP) – OSI layer-2 protocol which ensures a loop free topology for any bridged LAN. 17 of 54

Range Ring Topology Idea outputs Fiber Copper outputs 18 of 54 outputs

How well does it work? u u u 19 of 54 Grandmaster, 7 x 1588 Sync. Switches, 1 x slave Packet arrival jitter at slave < 400 ns <58 ns error per switch

When to use the Sync. Switch u Probably need a Sync. Switch… § If data & timing packets travel the same network § If measured error at slave is *not* acceptable § If there are traffic bottlenecks at switches § If Sub millisecond timing is required § Absolutely if <1 ms timing required u Probably don’t need a Sync. Switch… § If measured error at slave is acceptable § If desired timing accuracy at slave is in the milliseconds § If using a network of Hubs 20 of 54

Deployment 21 of 54 Data Bottleneck (port contention, 2 in, 1 out) Bottleneck (port contention, 5 in, 1 out) Data & Data & Data & Slave /Application Distribution /Network Grandmaster /Root Timing

Transparent Clock vs Boundary Clock u Transparent Clock § § § u Boundary Clock § § § § 22 of 54 Switch Measures switch induced Sync packet delay Modifies Follow-Up packet time stamp (adds the delay) Flattens time distribution topology Increases packet load on Grandmaster Switch & Clock Slave on one port Master on all other ports Built-in internal clock synchronized to the upstream master Cascaded Boundary Clocks can accumulate error Hierarchal time distribution topology Decreases packet load on Grandmaster Sync Packet tdepart – tarrive = delay Follow-Up Packet t 1 unmodified M Follow-Up Packet t 1 modified = t 1 unmodified + delay S M Slaves

XLi IEEE-1588 Grandmaster

XLi IEEE 1588 Grandmaster 1 x Port Master or Slave u u u Base XLi GPS Module 1 x IEEE 1588 module § IEEE 1588 -2002 compliant, v 1 § Operates as grandmaster or ordinary clock (master/slave) § Supports Best Master Clock Algorithm u TIET (Time Interval/Event Timing on J 1) § 1/sec measurement output from RS-232 and/or Telnet/NIC 24 of 54

TIET (Time Interval/Event Timing) u u u Measure the time interval difference between XLi Grandmaster 1 PPS and an external 1 PPS Application: Measure time transfer accuracy Master to Slave XLi TIET Output: 1/sec measurement output from RS-232 and/or Telnet/NIC Time Interval Master 1 PPS Slave 1 PPS 25 of 54

XLi 1588 Grandmaster 2 Port Master u u u Same base features as 1 x Port XLi Grandmaster Includes 2 x IEEE 1588 cards Configurations § Master/Master § Master/Slave 26 of 54 Master/Slave

Time. Monitor/Time. Analyzer Software (Option) u Collect and analyze time interval data from the XLi 1588 Grandmaster u Extensive graphing and charting functions u Perform extensive analysis on collected data u Collect data via RS-232 or TCP/IP interfaces u Runs on Windows® NT, 2000, XP 27 of 54 Chart View Functions

Testing with a Single Port Grandmaster u Third party IEEE 1588 slave characterization and network element delay measurements. § Baseline the slave (via crossover or hub) § Substitute network elements or topologies for study and characterization 28 of 54

Testing with a Dual Port Grandmaster u The XLi Grandmaster hosts a second IEEE 1588 module that acts as a slave § § 29 of 54 Baseline the XLi card slave (via crossover or hub) Substitute network elements or topologies for study and characterization

One Way Path Latency Testing u u u 30 of 54 Network separates the Grandmaster from the slave by an inconvenient distance. One XLi Grandmaster operates as a master Remote Grandmaster is configured with the IEEE 1588 module operating as a slave Slave module 1 PPS compared to GPS referenced XLi clock. GPS time is the common time reference

IEEE-1588 v 2 in the XLi GM u What § Support IEEE-1588 v 2 Default Profile u When § Fall 2008 u How § ECO in new models § TBD regarding update to fielded models u Price § No price change to existing XLi GM u Upgrades to fielded XLi GM units § Details and price TBD 31 of 54

Looking ahead…. . …at IEEE-1588 v 2 (PTPv 2) …at the big picture

IEEE-1588 v 2 Status u From the source… 3/14/2008 Please note that this is still a draft standard. . . that has been submitted to the IEEE for final approval. . . The approval is on the Rev. Com agenda for their 26 March 2008 meeting. . . If the draft is approved the IEEE editorial staff typically takes several months before the final version of the standard is available. This editorial process does not permit any technical changes. d e v o pr p A Regards, John C. Eidson Chair P 1588 33 of 54

IEEE 1588 v 2 Main Elements u u u u u 34 of 54 New message types and formats More message rate choices Unicast Fault Tolerance Alternative timescales Transparent clocks On the fly timestamps Profiles Security More here than any one vendor will implement in a single solution

Message Update Intervals PTPv 1 u 1, 2, 4, 16, 64 seconds Default 35 of 54 PTPv 2 u More than 18 hexillion choices u As small as 30 fs u As large as 3 days u No profile will support all of these choices

Unicast Messages PTPv 1 u All messages multicast u Every node in the same subnet hears every message PTPv 2 u Optional unicast mode u Slaves request unicast stream § Sync update interval u Broadcast (1: all) 36 of 54 Multicast (1: group) Master can grant none, all or part of request Unicast (1: 1)

Alternate Time Scales PTPv 1 u TAI is only allowed time scale u TAI has no leap seconds u UTC offset field u Flag indicate unknown accuracy 37 of 54 PTPv 2 u Alternative time scales allowed u Feature pushed into standard by Symmetricom u Allows for time scales with leap seconds or DST jumps

Profiles PTPv 1 u v 1 tailor made for industrial automation 38 of 54 PTPv 2 u Many optional features u Profiles limit choices u Profiles created by industry specific standards body

Looking ahead…. . …at IEEE-1588 v 2 (PTPv 2) …at the big picture

Slave /Application Distribution /Network Grandmaster /Root 1588 marketplace snapshot… 40 of 54 XLi GM NI PCI 1588 (GPS) Meinberg M 600/PTP Westermo Ruggedcom PTP Router Time. Provider 5000 Sync. Switch Hirschman BC Westermo TC Rockwell + Cisco ? ? Techron NI PCI 1588 XLi GM Meinberg Syncbox ZHW ?

Symmetricom Directions u Symmetricom Corporate § Committed to packet based timing solutions u Timing Test & Measurement Division (TTM) § Sync. Switch TC 100 Transparent Clock – IEEE-1588 v 2 support coming soon § XLi Grandmaster – IEEE-1588 v 2 support by year end § IEEE-1588 v 2 will eventually be in most clock form factors – 1 U clocks – Bus cards – Custom modules 41 of 54

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