1. ECEN5553 Telecom Systems Dr
ECEN5553 Telecom Systems Dr. George Scheets Week #8 Readings: [14a] "Can You Trust Your Fridge" [14b] "How a Teakettle Can Kill Your Cloud" [15a] "Hacking the Voter" [15b] "Hacking a Voting Machine" [16] "Voice Over the Internet: A Tutorial" Exam 1 Final Results (90 points max) Hi = 88.4, Low = 37.2, Average = 70.80, Deviation = A > 80, B > 67, C > 58, D > 49 Outline: Lecture 22, 5 October (Live) No later than 12 October (Remote DL) Exam #2: 24 October (Live & Local DL) No Later than 31 October (Remote DL)

2. Outlines Received due 5 October (local) 12 October (remote)
64 %

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

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

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

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

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

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

9. Queue Length @100% Load Will tend to increase w/o Bound.

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

11. 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.

12. Real vs Artificial Trace
100 Seconds
Real Traffic
100 Seconds
Artificial M/M/1 Traffic

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

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

15. Real vs Artificial Trace
27.78 Hours
Real Traffic
27.78 Hours
Artificial M/M/1 Traffic

16. Self Similar Behavior

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

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

19. 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

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

21. Packet Switch StatMux Trunking Pure Internet (or Ethernet) Model
Fixed Rate Traffic
Router
SONET & OTN
(Ethernet)
Bursty Data Traffic
Assumptions:
All Fixed Rate Traffic is packetized.
All traffic is Statistically Multiplexed onto the trunk BW.

22. Internet Service Provider Backbone
Trunks
Packet
Aware
Leased Line
Router
StatMux, Packet Switched Network, Full Duplex Trunks.
Access lines mostly attach to routers.

23. ATM Trunking (In Nineties, claimed as Tomorrow's Network Model)
Fixed Rate Traffic
ATM
Switch
SONET OC-N
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.

24. ATM Backbone Trunks Leased Line Cell Aware ATM Switch
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.

25. Circuit Switch TDM Trunking (Eighties 'Private Line' Network Model)
Fixed Rate Traffic
TDM
Switch
Fiber, Cable,
& Microwave
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.

26. Carrier Leased Line Backbone
Trunks
Byte
Aware
Leased Line
Cross-Connect
TDM, Circuit Switched Network, Full Duplex Trunks.
Access lines mostly attach to routers, FR & ATM
switches, TD Muxes, & cross connects of other carriers.

27. Hybrid TDM Trunking (Network Model for older Carriers)
Fixed Rate
TDM
Switch
Packet Switch
SONET
Bursty Data
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.

28. Fixed Rate Traffic: CSTDM bandwidth based on Peak Rates
Hybrid Network
Trunks
Byte
Aware
Leased Line
Cross-Connect
Fixed Rate Traffic: CSTDM bandwidth based on Peak Rates
Bursty Traffic: Access lines aggregated onto higher load trunk. Packet Switch StatMux Trunks are CSTDM.

29. Voice Quality vs. Bit Rate
G.711
G.729
G.728
G.726
G.723.1
Bit Rate (Kbps)

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

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

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

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

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

35. 70’s & 80’s Fixed Rate Voice Dominates
Data
Voice
70’s & 80’s
time

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

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

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

39. By 2005, Data Dominated
Data
Voice
time
2005

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

41. What's the impact of Video?
Video #1 since 2010, is a packet switched statmux network best?
Yes. Most video coders are variable rate.
Two changes to make the network more video friendly…
Might be a good idea to increase Ethernet's maximum packet size.
All packets with bit errors shouldn't be dropped
Voice/Video dropped packet = lower quality
Better quality possible if payload delivered

42. 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.

43. 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
Early 00's - Mostly Bursty Traffic
Data Networks moving voice on the side
10's - Mostly Video
Data Networks moving video Data & voice on the side

44. 1990 Marketing Glossy

45. 1990 Marketing Glossy

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

47. A/D Convertor m(t) volts (air pressure) 1/8000 second time (sec)
Step #1)
Sample the waveform at rate > 2*Max Frequency.
Telephone voice is sampled at 8,000 samples/second.

48. A/D Convertor Legacy Wired Telephone System uses PCM
Pulse Code Modulation One of N possible equal length Code Words is assigned to each Voltage N Typically a Power of 2 Log2N bits per code word
Wired Phone System: N = 256 & 8 bits/word
Compact Disk: N = 65,536 & 16 bits/word

49. A/D Convertor. 1 bit/sample.
Example) N = 2. Assign 0 or 1 to voltage.
3.62 v, output a 1 t1
time (sec)
0 < Voltage < +5v, Assign Logic 1
-5v < Voltage < 0, Assign Logic 0
Bit Stream Out =

50. 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

51. A/D Convertor. 1 bit/sample.
Input to the transmitter.
Output at the receiver.
+2.5 v
-2.5 v
Considerable Round-Off error exists.

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

53. A/D Convertor. 2 bits/sample.
Input to the transmitter.
Output at the receiver.
+3.75 v
+1.25 v
-1.25 v
-3.75 v
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.

54. 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 (1 byte, 8000 times/second)

55. Compact Disk Bandwidth ≈ 20,000 Hertz A/D Converter D/A 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

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

57. 1/8th Second of Voice

58. 1/8th Second of Voice

59. 1/8th Second of Voice

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

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

62. 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