Technology Evaluation for Tim e Sensitive gy Data Transport Report - - PowerPoint PPT Presentation

Technology Evaluation for Tim e Sensitive gy Data Transport

Report and status for subtask in JRA1 GN3 JRA1 Workshop, 20st-22nd of November, Copenhagen Henrik Wessing, Task leader

Tim e Sensitive Transport - Agenda

• Motivation and objectives
• Motivation and objectives

– ”Is it worth establishing circuit based paths or do we survive with the packet based solutions?”

• Technologies and layering
• Technologies and layering
• Delay verification through test equipment and OAM
• Physical layer
• OTN layer
• OTN layer
• MPLS-TP and PBT
• Measurements
• Conclusions and continued work
• Conclusions and continued work

Low delay is a key property

• Synchronising atomic clocks
• Synchronising atomic clocks
• Online music production (LOLA)

– Low Latency audio and video conferencing – Delay < 35-40 ms (for network) y ( ) – Jitter < 3 ms – Characterised by many small packets

• Telemedical surgery

Picture from presentation by Claudio Allochio, GARR

– Roundtrip delay < 150 ms – Gb/ s bandwidth due to no compression

• Interconnection of data centres

– NREN operating as network for DC – NREN operating as network for DC.

• Banking

– Stock exchange algoritms can utilise reduction of delays in msec and usec range – Not a clear NREN task! – According to The Telegraph:

• ”… that a one millisecond advantage could be worth up to

$100m a year to the bottom line of a large hedge fund.”

And m ore and m ore services em erges

Remote backup

Delay sensitive Delay tolerant ve

• Variety of services

3D streaming Internet surfing with video Internet surfing Grid computing Thin Clients Tele Health

• r Sensitiv

Bandwidth

• Different requirements
• End to end QoS in focus

Email Mobile gaming Ultra HD TV

Err B

End to end QoS in focus

• Delay key issues

Ultra HD TV Stereoscopic TV Video Conferencing IP Telephony (U)HD Video Stream Video Streaming

ndwidth r tolerant

Online Distributed Environments Home monitoring

Ban Error

Technologies investigated

C t k / M t t k

• Campus networks / Metro networks

– Traditionally packet based (L3/ L2) depending on operational use

• Core / NRENs (GEANT)

P k t i itb d – Packet or circuitbased

• Methodology

– Layered approach from physical layer and up – Qualifying and quantifying delay parameters

Service (IP)

Layer 2 (ETH / MPLS-TP) L1 S b l th l (OTN ODUk) L1 Subwavelength layer (OTN - ODUk) L0 DWDM layer

Measuring delay – External test or OAM

• Delay measurements using external test equipment
• Delay measurements using external test equipment
• Delay measured between Maintenance association End Points

– Different levels acoording to domain

EF 35 From M

OAM – Delay and loss statistics

• Metro Ethernet Forum specifies delay statistics (MEF 10 2)
• Metro Ethernet Forum specifies delay statistics (MEF 10.2)
• Frame delay (range/ mean/ jitter) - histograms
• Frame Loss Ratio - counters
• Availability
• One way FD utilising timestamps and sequence numbers (MEF 35 IA)
• One way FD utilising timestamps and sequence numbers (MEF 35 IA)

– Real data or as added synthetic frames – Synchroneous clocks required – (or estimated from two way FD)

• Performance Monitoring solutions

Choice depending on single or dual ended – Choice depending on single or dual ended – Synthetic frames must match real frames

• Communication messages

– Delay Measurements Message (DMM)/ Delay Measurement Response (DMR) R lt t d i bi f h t i t l

• Results stored in bins for each measurement interval

PM Solution MEG Type(s) Measurement Technique for Loss PM Function(s) Mandatory

• r Optional

PM‐1 point‐to‐point multipoint Synthetic Testing Single‐Ended Delay Single‐Ended Synthetic Loss Mandatory PM‐2 point‐to‐point multipoint n/a Dual‐Ended Delay Optional PM 3 i t t i t Counting Si l E d d S i L O ti l PM‐3 point‐to‐point g Service Frames Single‐Ended Service Loss Optional

Dedicated test equipm ent

• Agilent (now Ixia) N2X test solution
• Main advantage: You define which packet sizes and load to test with
• Main advantage: You define which packet sizes and load to test with
• RFC2544 compliant
• Measuring loss, signal power, delay, jitter etc.
• From services to fibres
• From services to fibres

Physical layer ( L0 )

• Physical layer (L0)
• Physical layer (L0)

– Propagation delay in fiber. Well defined.

• 1 km approxim ately 5 usec

DCF adds delay May use DCM – DCF adds delay. May use DCM. – Delay in modulation formats depending on technology in sub usec range

• QPSK QAM OFDMA
• QPSK,QAM, OFDMA …

– Transponders/ Muxponders

• ~ 5-10 usec

For m edium to long range applications: Propagation is the only significant L0 delay

Optical Transport Netw ork ( OTN) – L1

• Physical Media Independent layer (L1)

general

• Physical Media Independent layer (L1) - general

– Mapping from higher layer to L1 – Forward Error Correction OTN

• OTN

– Basically a technology to replace SDH/ SONET better suited for ethernet transport. Timestamping for Delay Measurement Message and Delay – Timestamping for Delay Measurement Message and Delay measurement reply (DMM/ DMR) – Vendor support: All major vendors support ODU switching

OTN ( I I ) – Measurem ent scenarios

• Lab measurements using Alcatel Switches
• Lab measurements using Alcatel Switches

– Triangular setup

• CPH - CPH -HAM
• Loops in triangle to estimate delays from

Loops in triangle Delay contribution 1 1 GFP mapping and demapping Total fibre propagation delay

p g y mapping and FEC processing

• Expected delays

– usec range (OTN mapping and processing) Res lts sing e te nal N2X teste and OAM

2 x OTN switching latency 2 1 GFP mapping and demapping T t l fib ti d l

• Results using external N2X tester and OAM

information

Total fibre propagation delay Triangle fibre propagation delay 5 x OTN switching latency 3 1 GFP mapping and demapping Total fibre propagation delay

OTN switch N2X tester

2 x Triangle fibre propagation delay 8 x OTN switching latency

OTN switch OTN switch OTN switch OTN switch

L2 – MPLS TP and PBT – Packet handling

• MPLS TP
• MPLS TP

– Two flavours: MPLS-TP and T-MPLS – No signalling protocol – Legacy Ethernet can be encapsulated in PW transported over MPLS LSP Delay contributions – Delay contributions

• Label processing
• Store and forward or wire speed as no CRC
• Lower priority packet may delay if in process

Payload = FCS l d FCS FCS

• PBT

– Ethernet for transport purposes VLAN Q i Q MAC i MAC

TPI D = 802.1ad frame with or without FCS

I -TAG

TPI D Payload

C-TAG

TPI D Payload TPI D Payload FCS

16 bits 32 bits

– VLAN -> Q-in-Q -> MAC-in-MAC – Delay contributions

• MAC table lookup
• Store and forward due to CRC

B-DA

TPI D TPI D

B-TAG B-SA DA

TPI D TPI D

S-TAG SA

TPI D

DA

TPI D

Q-TAG SA

TPI D

DA SA 48 bits 48 bits 16 bits 16 bits 16 bits

– Dependent on packet length

• Lower priority packet may delay if in process

PBT Lab scenarios

PBT switch

Simple PBT

Delay in 1, 2, 3, 4 and 5 switches Results next page

PBT switch N2X tester PBT switch s tc

p g

PBT switch PBT switch

PBT over OTN

Mapping between OTN and PBT Mapping between OTN and PBT

• Crossconnect version
• Terminate in PBT version

PBT m easurem ents – Sim ple PBT

100,00 120,00 140,00 64 bytes 512 bytes 1500 bytes 60,00 80,00 0,00 20,00 40,00

• Delay in usec depending on number of PBT switches
• For Jumbo frames of 9000 appr 80 usec per node (400 usec for 5 nodes)

1 2 3 4 5

• For Jumbo frames of 9000 appr. 80 usec per node (400 usec for 5 nodes)
• Clear dependence on packet length
• Processing max ethernet size packet equals 4-5 km transmission!!

For Jumbo: 16 km transmission! – For Jumbo: ~ 16 km transmission!

Dependence on load p

• All numbers in usec

25

• Jumbo frames included only in

text

• Vendor specific

15 20 64 512 1500

• Vendor specific
• 1Gbps
• Graph: Delay dependent on

10

load

Delay Load 64 512 1500 9000 10 9,203 13,77 22,741 82,785 20 9 208 13 779 22 743 82 787

5

20 9,208 13,779 22,743 82,787 30 9,221 13,784 22,748 82,781 40 9,214 13,766 22,74 82,779 50 9,232 13,781 22,732 82,773 60 9,233 13,781 22,732 82,776

10 20 30 40 50 60 70 80 90 100

, , , , 70 9,325 13,783 22,746 82,787 80 9,439 13,795 22,74 82,791 90 9,561 13,818 22,746 82,775 100 10,157 14,742 23,602 83,554

Transpacket FUSI ON H1 devices Transpacket FUSI ON H1 devices

Allows wavelength-grade Quality of Service (QoS). – Ultra-low latency ultra-low latency variation – Ultra-low latency, ultra-low latency variation – Combined circuit and packet switching

• GST: Guaranteed traffic (circuit based)
• SM: Statistically multiplexed BE traffic

1e+05 1e+06

(us)

GST SM

y p

Inputs Outputs High P. High P. Inputs Outputs High P. High P.

1e+03 1e+04 1e+05

Average packet delay (us Sync problem: Packet delay variation Low P. SM (Low P.) No PDV ultra‐low latency, zero packet loss Sync problem: Packet delay variation Low P. SM (Low P.) No PDV ultra‐low latency, zero packet loss

1e+02 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

A Normalized lightpath load (10GE)

Measurement with GST and SM

Inputs Output ( ) GST u a o a e cy, e o pac e oss Inputs Output ( ) GST u a o a e cy, e o pac e oss

GST and M Measurement with GST and SM through 3 switches with long fibre spans

• Prop. delay: 266 usec

No SM imSpact on GST flow. SM

• nly inserted if ”gap” is large

enough. p y Switching delay: 45 usec No delay variation for GST

Conclusion and continued w ork

• Subtask within GN3 JRA1 to identify and provide guidelines for choice between packet or circuit
• Subtask within GN3 JRA1 to identify and provide guidelines for choice between packet or circuit

based transport

• Relevant application

– LOLA – Online entertainment production – Telemedical applications Telemedical applications – Banking

• Common understanding of the different layers achieved
• Delay assessment using test equipment or inline OAM functions.
• Methodology -> From L0 -> L3
• Methodology -> From L0 -> L3

– Physical layer – OTN transport – MPLS-TP or PBT -

• Measurements on PBT showing high dependence on packet lenghts
• Measurements on PBT showing high dependence on packet lenghts.
• Work to be done in future

– Conduct similar measurements with MPLS-TP – Include OTN in the loop Verify PBT measurements with another vendor – Verify PBT measurements with another vendor – Application on top … LOLA?