ECEN5553 Telecom Systems Dr. George Scheets Week #8 Readings: [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 = A > 78, B > 64, C > 55, D > 46

Outlines Received due 8 October (local) 15 October (remote) 61 %

802.3 Ethernet Packet Format MAC Destination Address MAC Source Address CRCData + Padding Bytes: IPTCP

Provider Backbone Bridge Carrier Ethernet Packet (Simplified) MAC Destination Address MAC Source Address CRCData + Padding Bytes: IPTCP Carrier MAC Destination Address Carrier MAC Source Address n Carrier Edge switches prepend customer Ethernet frames with provider frames. u # Carrier MAC addresses = # Carrier edge switches Carrier VLAN Tag

LAN Carrier Ethernet WAN/MAN E1 EthernetSwitch LAN Every Carrier Switch is an Edge Switch here. Edge Switches learn MAC addresses of serviced end devices. E1 must learn Yellow & Orange MAC & VLAN addresses. LAN

Carrier Ethernet Switching (Simplified) n Unicast packet arrives with unknown customer destination MAC address u Source Carrier Edge Switch Examines Customer VLAN tag & source MAC address Maps to Carrier VLAN tag Carrier Edge Switch MAC address Appends Carrier Header u Destination Carrier Edge Switch Examines & Removes Carrier Header Forwards based on Customer MAC address

Carrier Ethernet Switching (Simplified) n Broadcast packet arrives u Source Carrier Edge Switch Examines Customer VLAN tag & source MAC address Maps to Carrier VLAN tag Carrier Edge Switch MAC address(es) Appends Carrier Header Selectively Floods u Destination Carrier Edge Switch Examines & Removes Carrier Header Forwards based on Customer VLAN

Carrier Ethernet Status n 2009 U.S. Market Revenue $1.5 Billion u 2010 $3.2 Billion u 2013 $5.5 Billion u 2016 $11.1 Billion (projected) u 2018 $13 Billion (projected) n Backhaul from wireless cell sites a major growth area source:

MAN/WAN Connectivity Options n Carrier Ethernet u Switches are Ethernet frame aware F I/O decisions based on Layer 2 Ethernet Address u Virtual Circuits can be used u StatMux F BW required based more so on average input rates u Pricing function of peak rate, CIR, priority, and maybe distance u On the way in. F 21st century version of Frame Relay

Carrying Capacity Line Speed Active Idle Application Traffic Overhead Carrying Capacity = Traffic(bps)/Line Speed(bps) Goodput = Application Traffic Carried (bps)

Queue Length n 100,000,000 bps output trunk n 100,000,001 bps average input n Average Input rate > Output rate n Queue Length builds up (without bound, in theory)

Queue Length n 100,000,000 bps output trunk n 99,999,999 bps average input n Average Input rate < Output rate n Queue Length not infinite......but very large

Queue 100% Load Output capacity = 7 units Input = 7 units on average (two dice rolled) n t1: input = 4, output = 4, queue = 0 n t2: input = 5, output = 5, queue = 0 n t3: input = 4, output = 4, queue = 0 n t4: input = 7, output = 7, queue = 0 n t5: input = 11, output = 7, queue = 4 n t6: input = 10, output = 7, queue = 7 n t7: input = 6, output = 7, queue = 6 n t8: input = 5, output = 7, queue = 4 n t9: input = 8, output = 7, queue = 5 n t10: input = 11, output = 7, queue = 9 This queue will tend to get very large over time.

Queue Load Will tend to increase w/o Bound.

"Die Roll" Queue Lengths 100% Load 101% Load 99% Load, Average Queue = 44.46

Real vs Artificial Trace 10 Seconds Real 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 Trace 100 Seconds Real Traffic 100 Seconds Artificial M/M/1 Traffic

Real vs Artificial Trace 16.7 Minutes Real Traffic 16.7 Minutes Artificial M/M/1 Traffic

Real vs Artificial Trace 167 Minutes Real Traffic 167 Minutes Artificial M/M/1 Traffic

Real vs Artificial Trace Hours Real Traffic Hours Artificial M/M/1 Traffic

Self Similar Behavior

Infinite Length Queue (Classical StatMux Theory) 0% 100% Trunk Offered Load Probability of dropped packets Average Delay for delivered packets

Finite Length Queue (Real World StatMux) 0% 100% Trunk Offered Load Probability of dropped packets Average Delay for delivered packets Classical Self-Similar You could fully load StatMux trunk lines... but your customers would be screaming at you due to lousy service.

Switched Network Carrying Capacity  Line Speed: Traffic injection speed  Efficiency: Ability to use that Line Speed  Throughput: bps of traffic (+ overhead) moved  = Efficiency * Line Speed  Carrying Capacity: Ability to usefully use Line Speed  Accounts for packet overhead  Accounts for inability to fully load trunk lines with StatMux'd traffic & still have a usable connection  Goodput: bps of application traffic moved  = Carrying Capacity * Line Speed

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

Packet Switch StatMux Trunking (Pure Internet Model) Router Fixed 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 Backbone Router Trunks Leased Line Packet Aware StatMux, Packet Switched Network, Full Duplex Trunks. Access lines mostly attach to routers.

ATM Trunking (In Nineties, claimed as Tomorrow's Network Model) ATM Switch 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 Backbone ATM Switch Trunks Leased Line Cell 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) TDM Switch 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 Backbone Cross-Connect Trunks Leased Line Byte 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) TDM Switch Fixed Rate Bursty Data Packet Switch 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 Network Cross-Connect Trunks Leased Line Byte Aware Fixed Rate Traffic: CSTDM bandwidth based on Peak Rates Bursty Traffic: Access lines aggregated onto higher load trunk. Packet Switch StatMux Trunks are CSTDM.

Voice Quality vs. Bit Rate Bit Rate (Kbps) Quality G.728 G.711 G G.729 G.723.1

Switched Network Carrying Capacities High Speed Trunk Carrying Capacity Circuit Switch TDM Packet Switch StatMux Cell Switch StatMux Hybrid 0% Bursty 100% Bursty 100% Fixed Rate 0% Fixed Rate Offered Traffic Mix

Switched Network Carrying Capacities Hybrid Network Carrying Capacity Circuit Switch TDM Hybrid all bursty data traffic groomed onto packet network 0% Bursty 100% Bursty 100% Fixed Rate 0% Fixed Rate Offered Traffic Mix

Switched Network Carrying Capacities Hybrid Network Carrying Capacity Hybrid no data traffic groomed onto packet network 0% Bursty 100% Bursty 100% Fixed Rate 0% Fixed Rate Offered Traffic Mix

Switched Network Carrying Capacities Hybrid Network Carrying Capacity real world network 0% Bursty 100% Bursty 100% Fixed Rate 0% Fixed Rate Offered Traffic Mix

Switched Network Carrying Capacities Convergence Carrying Capacity Circuit Switch TDM Packet Switch StatMux Cell Switch StatMux 0% Bursty 100% Bursty 100% Fixed Rate 0% Fixed Rate Offered Traffic Mix

70’s & 80’s Fixed Rate Voice Dominates Voice Data time 70’s & 80’s

Switched Network Carrying Capacities Convergence Carrying Capacity Circuit Switch TDM 0% Bursty 100% Bursty 100% Fixed Rate 0% Fixed Rate Offered Traffic Mix

Turn of the Century A Mixed Traffic Environment Voice Data time 2000

Switched Network Carrying Capacities Convergence Carrying Capacity Cell Switch StatMux 0% Bursty 100% Bursty 100% Fixed Rate 0% Fixed Rate Offered Traffic Mix

Today, Data Dominates Voice Data time 2012

Switched Network Carrying Capacities Convergence Carrying Capacity Packet Switch StatMux 0% Bursty 100% Bursty 100% Fixed Rate 0% Fixed Rate Offered Traffic Mix

A Resolving Unknown... What impact will Video have? nAnAnAnAs video becomes dominant, is a packet switched statmux network best? uYuYuYuYes. Most video coders are variable rate. nTnTnTnTwo changes to make the network more video friendly… uMuMuMuMight be a good idea to increase Ethernet's maximum packet size. uAuAuAuAll packets with bit errors shouldn't be dropped FVFVFVFVoice/Video dropped packet = lower quality FBFBFBFBetter quality possible if payload delivered Having a few bits in error is better than a loss of 1460 bytes

Carrying Capacity...  Got bursty data traffic to move? A packet switched system using statistical multiplexing will allow you to service the most users given a fixed chunk of bandwidth.  Got fixed rate traffic to move? A circuit switched system will allow you to service the most customers given a fixed chunk of bandwidth.

WAN Trends  60's - Fixed Rate Voice Dominates  Voice Network moving data on the side  Mid to Late 90's – Mixed Traffic Environment  New Carriers – ATM  Older Carriers – Hybrid  10's – Mostly Bursty Traffic  Data Networks moving voice on the side

Example) Coding a Microphone Output time (sec) m(t) volts (air pressure) Energy from about ,500 Hz.

A/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 Convertor n Telephone System uses PCM n Pulse Code Modulation One of N possible equal length Code Words is assigned to each Voltage N Typically a Power of 2 Log 2 N bits per code word u Wired Phone System: N = 256 & 8 bits/word u Compact Disk: N = 65,536 & 16 bits/word

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 v, output a 1 t1 Bit Stream Out =

A/D Convertor. 1 bit/sample. Example) N = 2. Assign 0 or 1 to voltage. Far side gets (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. Input to the transmitter. Output at the receiver. Considerable Round-Off error exists v -2.5 v

time (sec) Example) N = 4. Assign 00, 01, 10 or < Voltage < 5, Assign 11 0 < Voltage < 2.5, Assign < Voltage < 0, Assign < Voltage < -2.5, Assign v, Assign 11 t1 Bit Stream Out = v -2.5 v A/D Convertor. 2 bits/sample

A/D Convertor. 2 bits/sample. Input to the transmitter. Output at the receiver. Receive 11? Output 3.75v Receive 10? Output 1.25v Receive 00? Output -1.25v Receive 01? Output -3.75v Reduced Round-Off error exists v v v v

Circuit Switched Voice (POTS)  Bandwidth ≈ 3,500 Hertz  A/D Converter  samples voice 8,000 times/second  rounds off voice to one of 256 voltage levels  transmits 8 bits per sample to far side  D/A Converter  receives 8 bit code word  outputs one of 256 voltage levels for 1/8000th second  64,000 bps

Compact Disk  Bandwidth ≈ 20,000 Hertz  A/D Converter  samples voice 44,100 times/second  rounds off voice to one of 65,536 voltage levels  transmits 16 bits per sample to far side  D/A Converter  receives 16 bit code word  outputs one of 65,536 voltage levels for 1/44100th second  705,600 bps

Sampling & Quantizing Examples  fs = 16 KHz  4096 quantiles  256 quantiles (approximate phone quality)  32 quantiles  4 quantiles (generally 2 levels used!)  4096 quantiles  fs = 16 KHz  fs = 8 KHz (some interference)  fs = 2 KHz  fs = 1 KHz

1/8th Second of Voice

Sources of POTS delay Local Loop PCM Coder TDM Trunk POTS TSI POTS TSI Intermediate Digital Voice Switches... TDM TrunkLocal Loop PCM Coder Trunk resources are dedicated to each voice call via TDM. Source CO Destination CO

Sources of VoIP delay Voice Coder Packet Switch Packet Switch Intermediate Packet Switches... StatMux Trunks Voice Decoder Trunk resources are randomly assigned to each voice call via Statistical Multiplexing. Packet Assembler Transmission Buffer Receiver Buffer

Voice (Video) on LAN (WAN)  More complex system than circuit switched voice  Packet Assembler  Transmitter Buffer  Receiver Buffer  End-to-End Delays > Circuit Switch TDM  Delay Variability > Circuit Switch TDM