ECEN5553 Telecom SystemsDr. George ScheetsWeek #8Readings:[16] "Voice over the Internet: A Tutorial"[17a] "Rapidly Recovering from Catastrophic Loss… "

[17b] "How IT Leaders Can Best Plan For Disaster"[18a] "Trading at the Speed of Light" [18b] "Is The U.S. Stock Market Rigged?"Outline

8 October 2014, Lecture 22 (Live)No later than 15 October (Remote DL)

Exam #1 Results (90 points)Hi = 84.2, Low = 43.8, Ave = 67.22, σ = 10.37A > 78, B > 64, C > 55, D > 46

ECEN5553 Telecom SystemsDr. George ScheetsWeek #8Readings:[16] "Voice over the Internet: A Tutorial"[17a] "Rapidly Recovering from Catastrophic Loss… "

[17b] "How IT Leaders Can Best Plan For Disaster"[18a] "Trading at the Speed of Light" [18b] "Is The U.S. Stock Market Rigged?"Outline

8 October 2014, Lecture 22 (Live)No later than 15 October (Remote DL)

Exam #1 Results (90 points)Hi = 84.2, Low = 43.8, Ave = 67.22, σ = 10.37A > 78, B > 64, C > 55, D > 46

OutlinesReceived

due 8 October (local)

15 October (remote)

OutlinesReceived

due 8 October (local)

15 October (remote)

61 %

802.3 Ethernet Packet Format802.3 Ethernet Packet Format

MACDestination

Address

MACSource

Address

CRCData + Padding

Bytes: 6 6 2

20 20 6-1460 4

IP TCP

Provider Backbone BridgeCarrier Ethernet Packet (Simplified)

Provider Backbone BridgeCarrier Ethernet Packet (Simplified)

MACDestination

Address

MACSource

Address

CRCData + Padding

Bytes: 6 6 2 6 6 2

20 20 6-1460 4

IP TCP

Carrier MACDestination

Address

Carrier MAC Source

Address

Carrier Edge switches prepend customer Ethernet frames with Carrier Edge switches prepend customer Ethernet frames with provider frames.provider frames. # Carrier MAC addresses = # Carrier edge switches# Carrier MAC addresses = # Carrier edge switches

Carrier VLAN

Tag

LAN

LAN

Carrier Ethernet WAN/MANCarrier Ethernet WAN/MAN

E1

EthernetEthernetSwitchSwitch

LANLAN

LAN

LAN

Every Carrier Switch is an Edge Switch here. Every Carrier Switch is an Edge Switch here.

Edge Switches learn MAC addresses of serviced end devices. E1 Edge Switches learn MAC addresses of serviced end devices. E1 must learn must learn YellowYellow & & OrangeOrange MAC & VLAN addresses. MAC & VLAN addresses.

LAN

LAN

LAN

Carrier Ethernet Switching (Simplified) Carrier Ethernet Switching (Simplified) Unicast packet arrives with unknown customer Unicast packet arrives with unknown customer

destination MAC addressdestination MAC address Source Carrier Edge SwitchSource Carrier Edge Switch

ExaminesExamines Customer VLAN tag & source MAC address Customer VLAN tag & source MAC address Maps toMaps toCarrier VLAN tag Carrier VLAN tag Carrier Edge Switch MAC addressCarrier Edge Switch MAC addressAppendsAppends Carrier Header Carrier Header

Destination Carrier Edge SwitchDestination Carrier Edge SwitchExamines & Removes Examines & Removes Carrier HeaderCarrier HeaderForwardsForwards based on Customer MAC address based on Customer MAC address

Carrier Ethernet Switching (Simplified) Carrier Ethernet Switching (Simplified) Broadcast packet arrivesBroadcast packet arrives

Source Carrier Edge SwitchSource Carrier Edge SwitchExaminesExamines Customer VLAN tag & source MAC address Customer VLAN tag & source MAC address Maps toMaps toCarrier VLAN tag Carrier VLAN tag Carrier Edge Switch MAC address(es)Carrier Edge Switch MAC address(es)AppendsAppends Carrier Header Carrier HeaderSelectively FloodsSelectively Floods

Destination Carrier Edge SwitchDestination Carrier Edge SwitchExamines & Removes Examines & Removes Carrier HeaderCarrier HeaderForwardsForwards based on Customer VLAN based on Customer VLAN

Carrier Ethernet StatusCarrier Ethernet Status

2009 U.S. Market Revenue $1.5 Billion2009 U.S. Market Revenue $1.5 Billion 2010 $3.2 Billion2010 $3.2 Billion 2013 $5.5 Billion2013 $5.5 Billion 2016 $11.1 Billion (projected)2016 $11.1 Billion (projected) 2018 $13 Billion (projected)2018 $13 Billion (projected)

Backhaul from wireless cell sites a major Backhaul from wireless cell sites a major growth areagrowth area

source: www.accedian.comwww.telecompetitor.com

MAN/WAN Connectivity OptionsMAN/WAN Connectivity Options Carrier EthernetCarrier Ethernet

Switches are Ethernet frame awareSwitches are Ethernet frame aware I/O decisions based on Layer 2 Ethernet AddressI/O decisions based on Layer 2 Ethernet Address

Virtual Circuits can be usedVirtual Circuits can be used StatMuxStatMux

BW required based more so on BW required based more so on averageaverage input rates input rates

Pricing function of peak rate, CIR, priority, and maybe Pricing function of peak rate, CIR, priority, and maybe distancedistance

On the way in.On the way in. 21st century version of Frame Relay21st century version of Frame Relay

Carrying CapacityCarrying Capacity

Line Speed

Active Idle

Application Traffic Overhead

Carrying Capacity = Traffic(bps)/Line Speed(bps)

Goodput = Application Traffic Carried (bps)

Queue LengthQueue Length

100,000,000 bps output trunk100,000,000 bps output trunk 100,000,001 bps average input100,000,001 bps average input Average Input rate > Output rateAverage Input rate > Output rate Queue Length builds upQueue Length builds up

(without bound, in theory)(without bound, in theory)

Queue LengthQueue Length

100,000,000 bps output trunk100,000,000 bps output trunk 99,999,999 bps average input99,999,999 bps average input Average Input rate < Output rateAverage Input rate < Output rate Queue Length not infinite...Queue Length not infinite...

...but ...but veryvery large large

Queue Length @ 100% LoadOutput capacity = 7 units

Input = 7 units on average (two dice rolled)

Queue Length @ 100% LoadOutput capacity = 7 units

Input = 7 units on average (two dice rolled)

t1: input = 4, output = 4, queue = 0t1: input = 4, output = 4, queue = 0 t2: input = 5, output = 5, queue = 0t2: input = 5, output = 5, queue = 0 t3: input = 4, output = 4, queue = 0t3: input = 4, output = 4, queue = 0 t4: input = 7, output = 7, queue = 0t4: input = 7, output = 7, queue = 0 t5: input = 11, output = 7, queue = 4t5: input = 11, output = 7, queue = 4 t6: input = 10, output = 7, queue = 7t6: input = 10, output = 7, queue = 7 t7: input = 6, output = 7, queue = 6t7: input = 6, output = 7, queue = 6 t8: input = 5, output = 7, queue = 4t8: input = 5, output = 7, queue = 4 t9: input = 8, output = 7, queue = 5t9: input = 8, output = 7, queue = 5 t10: input = 11, output = 7, queue = 9t10: input = 11, output = 7, queue = 9

This queue will tend to get very large over time.This queue will tend to get very large over time.

Queue Length @100% LoadWill tend to increase w/o Bound.

Queue Length @100% LoadWill tend to increase w/o Bound.

0 2 105 4 105 6 105 8 105 1 1060

2000

40003.409 10

3

0

queue5 j

1 1060 j 5

0 2 105 4 105 6 105 8 105 1 1060

1000

20001.983 10

3

0

queue5 j

1 1060 j 5

"Die Roll" Queue Lengths"Die Roll" Queue Lengths

0 2 105 4 105 6 105 8 105 1 1060

2000

40003.409 10

3

0

queue5 j

1 1060 j 5

100% Load

101% Load

99% Load, Average Queue = 44.46

Real vs Artificial TraceReal vs Artificial Trace

10 SecondsReal Traffic 10 Seconds

Artificial M/M/1 Traffic

Source: Willinger et al, "Self-Similarity through High Variability", IEEE/ACM Transactions on Networking, February 1997.

Real vs Artificial TraceReal vs Artificial Trace

100 SecondsReal Traffic 100 Seconds

Artificial M/M/1 Traffic

Real vs Artificial TraceReal vs Artificial Trace

16.7 MinutesReal Traffic 16.7 Minutes

Artificial M/M/1 Traffic

Real vs Artificial TraceReal vs Artificial Trace

167 MinutesReal Traffic 167 Minutes

Artificial M/M/1 Traffic

Real vs Artificial TraceReal vs Artificial Trace

27.78 HoursReal Traffic 27.78 Hours

Artificial M/M/1 Traffic

Self Similar BehaviorSelf Similar Behavior

Infinite Length Queue (Classical StatMux Theory)Infinite Length Queue (Classical StatMux Theory)

0% 100%Trunk Offered Load

Probability of dropped packets

Average Delay fordelivered packets

Finite Length Queue (Real World StatMux)Finite Length Queue (Real World StatMux)

0% 100%Trunk Offered Load

Probability of dropped packets

Average Delay fordelivered packets

Cla

ssic

al

Self

-Sim

ilar

You could fully load StatMux trunk lines... but yourcustomers would be screaming at you due to lousy service.

Switched Network Carrying CapacitySwitched Network Carrying Capacity

Line SpeedLine Speed: Traffic injection speed: Traffic injection speed EfficiencyEfficiency: Ability to use that Line Speed: Ability to use that Line Speed ThroughputThroughput: bps of traffic (+ overhead) moved: bps of traffic (+ overhead) moved

= Efficiency * Line Speed= Efficiency * Line Speed Carrying CapacityCarrying Capacity: Ability to : Ability to usefullyusefully use Line Speed use Line Speed

Accounts for packet overheadAccounts for packet overhead Accounts for inability to fully load trunk lines with Accounts for inability to fully load trunk lines with

StatMux'd traffic & still have a usable connectionStatMux'd traffic & still have a usable connection Goodput: Goodput: bps of application traffic movedbps of application traffic moved

= Carrying Capacity * Line Speed= Carrying Capacity * Line Speed

Carrying CapacityCarrying Capacity

Line Speed

Active Idle

Traffic Overhead

Carrying Capacity = (%Trunk Load) * (%Traffic) = Traffic(bps)/Line Speed(bps)

Packet Switch StatMux Trunking(Pure Internet Model)

Packet Switch StatMux Trunking(Pure Internet Model)

RouterFixed Rate Traffic

Bursty Data Traffic

Assumptions: All Fixed Rate Traffic is packetized. All traffic is Statistically Multiplexed onto the trunk BW.

SONET & OTN

Internet Service Provider BackboneInternet Service Provider Backbone

Router

TrunksLeased LinePacketAware

StatMux, Packet Switched Network, Full Duplex Trunks.Access lines mostly attach to routers.

ATM Trunking(In Nineties, claimed as Tomorrow's Network Model)

ATM Trunking(In Nineties, claimed as Tomorrow's Network Model)

ATMSwitch

Fixed Rate Traffic

Bursty Data Traffic

Assumptions: Fixed Rate Traffic gets CBR Virtual Circuits. CBR traffic gets near-TDM like service. Data Traffic is StatMuxed onto the remaining trunk BW.

SONET OC-N

ATM BackboneATM Backbone

ATM SwitchATM Switch

TrunksLeased LineCell

Aware

StatMux/TDM, Cell Switched Network, Full Duplex Trunks.Access lines mostly attached to ATM switches, and "ATM capable"

routers, FR switches, TD Muxes, & cross connects.

Circuit Switch TDM Trunking(Eighties 'Private Line' Network Model)Circuit Switch TDM Trunking

(Eighties 'Private Line' Network Model)

TDMSwitch

Fixed Rate Traffic

Bursty Data Traffic

Assumptions: All Traffic receives trunk bandwidth based on peak input rates. No aggregation. Data traffic consists of many slower speed, relatively lightly loaded circuits.

Fiber, Cable, & Microwave

Carrier Leased Line BackboneCarrier Leased Line Backbone

Cross-ConnectCross-Connect

TrunksLeased LineByte

Aware

TDM, Circuit Switched Network, Full Duplex Trunks.Access lines mostly attach to routers, FR & ATM

switches, TD Muxes, & cross connects of other carriers.

Hybrid TDM Trunking(Network Model for older Carriers)

Hybrid TDM Trunking(Network Model for older Carriers)

TDMSwitch

Fixed Rate

Bursty DataPacketSwitch

Assumptions: Bursty Data Traffic is all StatMuxed onto a common fabric (such as Frame Relay). Aggregate streams are TDM cross connected onto SONET. Trunk BW assigned based on peak rates.

SONET

Hybrid NetworkHybrid Network

Cross-ConnectCross-Connect

TrunksLeased LineByte

Aware

Fixed Rate Traffic: CSTDM bandwidth based on Peak RatesBursty Traffic: Access lines aggregated onto higher load trunk.

Packet Switch StatMux Trunks are CSTDM.

Voice Quality vs. Bit RateVoice Quality vs. Bit Rate

Bit Rate (Kbps)

QualityG.728

G.711G.726

8 16 32 64

G.729

G.723.1

Switched Network Carrying CapacitiesHigh Speed Trunk

Switched Network Carrying CapacitiesHigh Speed Trunk

Carrying Capacity

Circuit Switch TDM

Packet Switch StatMux

Cell Switch StatMux

Hybrid

0% Bursty 100% Bursty100% Fixed Rate 0% Fixed Rate

OfferedTraffic Mix

Switched Network Carrying CapacitiesHybrid Network

Switched Network Carrying CapacitiesHybrid Network

Carrying Capacity

Circuit Switch TDM

Hybrid

all bursty data traffic groomed onto packet network

0% Bursty 100% Bursty100% Fixed Rate 0% Fixed Rate

OfferedTraffic Mix

Switched Network Carrying CapacitiesHybrid Network

Switched Network Carrying CapacitiesHybrid Network

Carrying Capacity Hybrid

no data traffic groomed onto packet network

0% Bursty 100% Bursty100% Fixed Rate 0% Fixed Rate

OfferedTraffic Mix

Switched Network Carrying CapacitiesHybrid Network

Switched Network Carrying CapacitiesHybrid Network

Carrying Capacity

real world network

0% Bursty 100% Bursty100% Fixed Rate 0% Fixed Rate

OfferedTraffic Mix

Switched Network Carrying CapacitiesConvergence

Switched Network Carrying CapacitiesConvergence

Carrying Capacity

Circuit Switch TDM

Packet Switch StatMux

Cell Switch StatMux

0% Bursty 100% Bursty100% Fixed Rate 0% Fixed Rate

OfferedTraffic Mix

70’s & 80’s Fixed Rate Voice Dominates70’s & 80’s Fixed Rate Voice Dominates

Voice

Data

time70’s & 80’s

Switched Network Carrying CapacitiesConvergence

Switched Network Carrying CapacitiesConvergence

Carrying Capacity

Circuit Switch TDM

0% Bursty 100% Bursty100% Fixed Rate 0% Fixed Rate

OfferedTraffic Mix

Turn of the CenturyA Mixed Traffic EnvironmentTurn of the CenturyA Mixed Traffic Environment

Voice

Data

time2000

Switched Network Carrying CapacitiesConvergence

Switched Network Carrying CapacitiesConvergence

Carrying Capacity

Cell Switch StatMux

0% Bursty 100% Bursty100% Fixed Rate 0% Fixed Rate

OfferedTraffic Mix

Today, Data DominatesToday, Data Dominates

Voice

Data

time

2012

Switched Network Carrying CapacitiesConvergence

Switched Network Carrying CapacitiesConvergence

Carrying Capacity

Packet Switch StatMux

0% Bursty 100% Bursty100% Fixed Rate 0% Fixed Rate

OfferedTraffic Mix

A Resolving Unknown...What impact will Video have?A Resolving Unknown...What impact will Video have? As video becomes dominant, is a packet switched statmux network best?As video becomes dominant, is a packet switched statmux network best?

Yes. Most video coders are variable rate.Yes. Most video coders are variable rate.

Two changes to make the network more video friendly… Two changes to make the network more video friendly… Might be a good idea to increase Ethernet's maximum packet size.Might be a good idea to increase Ethernet's maximum packet size. All packets with bit errors shouldn't be droppedAll packets with bit errors shouldn't be dropped

Voice/Video dropped packet = lower qualityVoice/Video dropped packet = lower quality Better quality possible if payload deliveredBetter quality possible if payload delivered

• Having a few bits in error is better than a loss of 1460 bytesHaving a few bits in error is better than a loss of 1460 bytes

Carrying Capacity...Carrying Capacity... Got Got bursty data bursty data traffictraffic to move?to move?

A A packet switched system packet switched system using using statistical statistical multiplexing multiplexing will allow you to service the most will allow you to service the most users given a fixed chunk of bandwidth. users given a fixed chunk of bandwidth.

GotGot fixed rate fixed rate traffic to move?traffic to move?A A circuit switched circuit switched system will allow you to system will allow you to service the most customers given a fixed chunk service the most customers given a fixed chunk of bandwidth.of bandwidth.

WAN TrendsWAN Trends 60's - Fixed Rate Voice Dominates60's - Fixed Rate Voice Dominates

Voice Network moving data on the sideVoice Network moving data on the side Mid to Late 90's – Mixed Traffic EnvironmentMid to Late 90's – Mixed Traffic Environment

New Carriers – ATMNew Carriers – ATMOlder Carriers – HybridOlder Carriers – Hybrid

10's – Mostly Bursty Traffic10's – Mostly Bursty TrafficData Networks moving voice on the sideData Networks moving voice on the side

Example) Coding aMicrophone Output

Example) Coding aMicrophone Output

time (sec)

m(t) volts (air pressure)

Energy from about 500 - 3,500 Hz.

A/D ConvertorA/D Convertor

time (sec)

m(t) volts (air pressure)

Step #1)Sample the waveform at rate > 2*Max Frequency.Telephone voice is sampled at 8,000 samples/second.

1/8000 second

A/D ConvertorA/D Convertor Telephone System uses PCMTelephone System uses PCM

Pulse Code ModulationPulse Code Modulation One of N possible equal length Code One of N possible equal length Code Words is Words is assigned to each Voltageassigned to each VoltageN Typically a Power of 2N Typically a Power of 2LogLog22N bits per code wordN bits per code word Wired Phone System: N = 256 & 8 bits/wordWired Phone System: N = 256 & 8 bits/word Compact Disk: N = 65,536 & 16 bits/wordCompact Disk: N = 65,536 & 16 bits/word

A/D Convertor. 1 bit/sample.A/D Convertor. 1 bit/sample.

time (sec)

Example) N = 2. Assign 0 or 1 to voltage.

0 < Voltage < +5v, Assign Logic 1-5v < Voltage < 0, Assign Logic 0

3.62 v, output a 1

t1

Bit Stream Out = 1111110000111...

A/D Convertor. 1 bit/sample.A/D Convertor. 1 bit/sample.Example) N = 2. Assign 0 or 1 to voltage.

Far side gets... 1111110000111 (13 samples)Needs to output 13 voltages.What does a 1 represent? A 0?

Receive a 1? Output +2.5 v (mid-range)Receive a 0? Output -2.5 v (mid-range)

Hold the voltage until next sample

0 < Voltage < +5v, Assign Logic 1-5v < Voltage < 0, Assign Logic 0

A/D Convertor. 1 bit/sample.A/D Convertor. 1 bit/sample.

Input to the transmitter.Output at the receiver.

Considerable Round-Off error exists.

+2.5 v

-2.5 v

time (sec)

Example) N = 4. Assign 00, 01, 10 or 11.

2.5 < Voltage < 5 , Assign 110 < Voltage < 2.5, Assign 10-2.5 < Voltage < 0, Assign 00-5 < Voltage < -2.5, Assign 01

3.62 v, Assign 11

t1

Bit Stream Out =11111011111100 000000101011...

+2.5 v

-2.5 v

A/D Convertor. 2 bits/sampleA/D Convertor. 2 bits/sample

A/D Convertor. 2 bits/sample.A/D Convertor. 2 bits/sample.

Input to the transmitter.Output at the receiver.

Receive 11? Output 3.75vReceive 10? Output 1.25vReceive 00? Output -1.25vReceive 01? Output -3.75vReduced Round-Off error exists.

+3.75 v

+1.25 v

-1.25 v

-3.75 v

Circuit Switched Voice (POTS)Circuit Switched Voice (POTS) Bandwidth ≈ 3,500 HertzBandwidth ≈ 3,500 Hertz A/D ConverterA/D Converter

samples voice 8,000 times/secondsamples voice 8,000 times/second rounds off voice to one of 256 voltage levelsrounds off voice to one of 256 voltage levels transmits 8 bits per sample to far sidetransmits 8 bits per sample to far side

D/A ConverterD/A Converter receives 8 bit code wordreceives 8 bit code word outputs one of 256 voltage levels for 1/8000th secondoutputs one of 256 voltage levels for 1/8000th second

64,000 bps64,000 bps

Compact DiskCompact Disk Bandwidth ≈ 20,000 HertzBandwidth ≈ 20,000 Hertz A/D ConverterA/D Converter

samples voice 44,100 times/secondsamples voice 44,100 times/second rounds off voice to one of 65,536 voltage levelsrounds off voice to one of 65,536 voltage levels transmits 16 bits per sample to far sidetransmits 16 bits per sample to far side

D/A ConverterD/A Converter receives 16 bit code wordreceives 16 bit code word outputs one of 65,536 voltage levels for 1/44100th outputs one of 65,536 voltage levels for 1/44100th

secondsecond 705,600 bps705,600 bps

Sampling & Quantizing ExamplesSampling & Quantizing Examples fs = 16 KHzfs = 16 KHz

4096 quantiles4096 quantiles 256 quantiles (approximate phone quality)256 quantiles (approximate phone quality) 32 quantiles32 quantiles 4 quantiles (generally 2 levels used!)4 quantiles (generally 2 levels used!)

4096 quantiles4096 quantiles fs = 16 KHzfs = 16 KHz fs = 8 KHz (some interference)fs = 8 KHz (some interference) fs = 2 KHzfs = 2 KHz fs = 1 KHzfs = 1 KHz

1/8th Second of Voice1/8th Second of Voice

1/8th Second of Voice1/8th Second of Voice

1/8th Second of Voice1/8th Second of Voice

Sources of POTS delaySources of POTS delay

Local Loop

PCMCoder TDM Trunk

POTSTSI

POTSTSI

IntermediateDigitalVoice

Switches

...

TDM TrunkLocal Loop

PCMCoder

Trunk resources are dedicatedto each voice call via TDM.

Source CO

Destination CO

Sources of VoIP delaySources of VoIP delay

VoiceCoder

PacketSwitch

PacketSwitch

IntermediatePacket

Switches...

StatMuxTrunks

VoiceDecoder

Trunk resources are randomly assigned to each voice call via Statistical Multiplexing.

PacketAssembler

TransmissionBuffer

ReceiverBuffer

Voice (Video) on LAN (WAN)Voice (Video) on LAN (WAN)

More complex system than circuit switched More complex system than circuit switched voicevoice Packet AssemblerPacket Assembler Transmitter BufferTransmitter Buffer Receiver BufferReceiver Buffer

End-to-End Delays > Circuit Switch TDMEnd-to-End Delays > Circuit Switch TDM Delay Variability > Circuit Switch TDMDelay Variability > Circuit Switch TDM