ECEN5553 Telecom Systems I Lecture 11

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ECEN5553 Telecom Systems ILecture 11 12Read
9a "Protect Yourself Online" 9b "7 Online
Blunders" 9c "ID Leaks" 9d "How Close is
World War 3.0?" 10 "Controlled Chaos" 11a
"Nothing but Net" 11b "Why Argonne Pulled VoIP
Plug" 11c "IP PBX's Come Into Their Own
"Study for Midterm on Lecture 15 7 October
(live) Week of 13-17 October (distance
learning)Term Paper Outline due Lecture 16 14
October (live) Week of 20 - 24 October (distance
learning)
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OutlinesReceiveddue 14 October Lecture 16
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MID-TERM

• 1 Hour 15 minute Test during Lecture 15
• Practice shared LAN problems on the Web
• Know the last midterm (2 of 5 pages)
• Work 4 of 5 pages
• Closed Book Notes
• Calculators are NOT allowed...Set up numerical
  problem for full credit

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On Short Answer or Essay Questions

• To get "A" or "B", instructor needs to walk away
  with impression you have cursory knowledge
• Answer the Question!
• Memory Dump in the space provided
• Bullet form or Short Concise Sentences
  recommended
• Grader will look for "Power Point bullets"
• Tally number of bullets
• Compare to number on instructor's test
• Exact same bullets typically not required
• Got space? Anything else pertinent to add?
• It is NOT necessary to write small or fill up
  allotted space to get a good score!

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Ex) Internet thru OKC
640 Kbps
How big should the pipe to the ISP be? 300 Kbps
is inbound from ISP 640 Kbps circuit needed.
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Ex) Internet thru OKC
Detroit
ISP
576 Kbps
640 Kbps
Carrier Leased Line Network
OKC
448 Kbps
NYC
Router
Need to bump size of other 2 pipes. 194/186 I/O
_at_ NYC ? 448 Kbps 278/166 I/O _at_ DET ? 576 Kbps
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WAN Design (Link Reduction)

• Start with Traffic Matrix
• Examine Full Mesh
• Consider eliminating lightly used links
• Reroute affected traffic
• Compare costs at each iteration

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WAN Connectivity Options

• Internet
• Routers are packet aware
• Datagrams are assigned trunk BW via StatMux
• BW required based more so on average input rates
• Each packet individually routed
• MPLS enabled networks can use Virtual Circuits
• Pricing a function of connection size
• Possibly QoS if MPLS and/or DiffServe used

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Ex) Commodity Internet Corporate Connectivity
Detroit
384 Kbps
ISP Network
OKC
448 Kbps
320 Kbps
NYC
Router
Local Carriers dedicate 448, 384, 320 Kbps to
our use. ISP provides random Packet Switched
StatMux connectivity via datagrams.
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Ex) Commodity InternetCorporate Internet
Connectivity
Detroit
576 Kbps
ISP Network
OKC
640 Kbps
448 Kbps
NYC
Router
320/280 I/O _at_ OKC ? 640 Kbps 194/186 I/O _at_ NYC ?
448 Kbps 278/166 I/O _at_ DET ? 576 Kbps
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Ex) Internet with MPLS
Detroit
VC, OKC - Detroit
ISP Network
OKC
VC, NYC - OKC
NYC
Router
MPLS will allow end-to-end routes to be nailed
down (VCs). DiffServ could prioritize
corporate traffic along these specific routes.
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Internet Service Provider Backbone
Trunks
Leased Line
Router
ISP Routers assign BW for our use on random, as
needed basis via full duplex, StatMux'd, packet
switched trunks.
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Internet Service Provider Network
PC
Trunks
Leased Line
Router
Corporate customers might attach via Edge Router
Leased Lines.
WS
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Internet (Inside the Cloud)

• Infinite Buffers
• "OK" so long as Average Offered Input Rate Output Line Speed

Internet Router
100 Mbps Trunk
?? 1.54 Mbps Connections P(Access Line is
Active) 10
How many access lines can this switch
support? 100 Mbps/154 Kbps 649 (theoretically)
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Internet (Inside the Cloud)

• Negligible Buffers
• OK so long as Instantaneous Offered Input Rate
  

Internet Router
100 Mbps Trunk
?? 1.54 Mbps Connections P(Access Line is
Active) 10
How many access lines can this switch
support? With 404 users, 99.99 sure Input Rate
Line Speed
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Bounds on Packet Switch Carrying Capacity
100 Mbps Trunk, 1.54 Mbps Inputs with 154
Kbps average loads

• Lower Upper90 553 64999
  485 64999.9 439 64999.99
  404 649

Instantaneous Input
Where switch could operate
Where switch probably operates
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WAN Connectivity Options

• Leased Line
• Cross Connects are byte aware
• Circuit Switched
• Resources dedicated to customer use for duration
  of connection
• Connection Set-Up Procedure
• Coordinates byte time slot assignments between
  switches
• Bytes are assigned at 1/8000th second intervals
  (TDM)
• Switch then repetitively moves input bytes to
  designated output byte time slots
• Pricing a function of connection size distance

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Carrier Leased Line Network
Trunks
Byte Aware
Leased Line
Cross-Connect
Carrier reserves BW from pool for our use. Ex)
For a 384 Kbps connection, Cross-Connects assign
6 byte sized TDM time slots 8000 times/second
688000 384 Kbps.
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Carrier Leased Line Network
PC
Trunks
Byte Aware
Leased Line
Cross-Connect
Corporate customers might attach via Edge Router
Leased Lines.
WS
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Leased Lines (Inside the Cloud)

• OK so long as Sum of Input Line Speeds
  

Leased Line Cross-Connect
100 Mbps Trunk
?? 1.54 Mbps Connections P(Access Line is
Active) 10
How many access lines can this switch
support? 64
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Leased Lines (TDM)
Leased Line Cross-Connect

• TDM time slots are moved from input to output
• TDM switch is not "packet aware"
• Time slots are allocated whether or not there is
  any traffic on them

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Circuit Switched connections waste bandwidth for
bursty traffic.
traffic NYC to OKC
1.54 Mbps Line Speed
146 Kbps Average
time
Idle Time Active Time
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Given 100 Mbps of Bandwidth...

• 64 1.54 Mbps Circuit Switched TDM Customers
  with 154 Kbps average load
• 404 - 649 1.54 Mbps Packet Switched StatMux
  Customers with 154 Kbps average load
  99.99 availability

64 x 154 Kbps 9.856 Mbps
404 x 154 Kbps 62.22 Mbps
More Bursty Data Traffic can be moved with the
Packet Switched StatMux network.
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Switched Network Carrying Capacities
Carrying Capacity
Packet Switch StatMux
Circuit Switch TDM
0 Bursty
100 Bursty 100 Fixed Rate
0 Fixed Rate
Offered Load
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Network Cost...

• Can be spread over 64 Leased Line customers
• Can be spread over 404 Internet customers
• The Internet Is a Packet Switched StatMux
  network Largely hauling bursty data
  traffic Effectively hauling bursty data traffic
  Inexpensive (compared to a Leased Line)

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Internet Performance
This type of plot valid for all real world full
duplex statistically multiplexed
switches Ethernet, Internet, Frame Relay
Probability of dropped packets
Average Delay for delivered packets
0
100
Trunk Offered Load
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Internet Performance Effect of priorities
Average Delay for low priority packets Average
Delay for all delivered packets Average Delay
for high priority packets
0
100
Trunk Offered Load
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Internet Performance Effect of priorities
Probability of low priority drops Overall
Probability of dropped packets Probability
of high priority drops
0
100
Trunk Offered Load
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Internet Backbone Engineering

• Option A)Deploy best effort RoutersRapidly
  Deploy Trunk BandwidthKeep Trunks Lightly Loaded
• Delays will be small
• Dropped packets will be few
• Quality fine for all traffic

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Backbone Engineering Option A
Probability of dropped packets
Average Delay for delivered packets
0
100
Keep Trunks Lightly Loaded
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Internet Backbone Engineering

• Option B)Deploy more complex QoS
  enabled Routers Deploy fewer, more heavily
  loaded Trunks Give preferential treatment to
  Voice/Video
• Option A seems to be preferred today

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Backbone Engineering Option B High Priority
delay at 50 Load Delay for all
traffic at 20 Load
Average Delay for low priority packets Average
Delay for all delivered packets Average Delay
for high priority packets
0
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Heavier Trunk Load
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Internet Traffic Growth
Source August 2007 Network World
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Frame Relay

• ANSI Standard covering OSI Layer 2
• Accessed by Routers or FRADs
• Derived from X.25 Protocol Dumps almost all
  error checking Requires fiber on the long haul
• Uses Permanent Virtual Circuits (PVCs) VC
  differs from Datagram Long Term
  Connection Requires Carrier intervention to
  change

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Frame Relay

• 7 Application
• 6 Presentation
• 5 Session TCP
• 4 Transport TCP
• 3 Network IP
• 2 Data Link Frame Relay
• 1 Physical

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Wide Area Connectivity Options

• Frame Relay Network
• Switches are packet aware
• Virtual Circuit is assigned trunk BW via StatMux
• BW required based more so on average input rates
• Routing through system determined in advance
• Pricing a function of PCS, CIR, and maybe distance

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Frame Relay

• Committed Information Rate (CIR) Is a Quality of
  Service Guarantee "Guaranteed" minimum
  Bandwidth Should be set average traffic
  during appropriate peak period
• Port Connection Speed a.k.a. Port Speed or Burst
  Speed Bandwidth you can burst to
  provided network capacity exists.

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Frame Relay Packet Format
3 20 20 up to
8,146 3
FR Header
FR Trailer
Data Padding
IP
TCP
Header includes 10 bit Data Link Connection
Identifier (DLCI) - Locally Unique (FR
ports)Trailer includes 2 byte CRC Sequence I/O
decisions based on FR address look-up table.
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Frame Relay Backbone
Trunks
Leased Line
FR Switch
Frame Relay Cloud Full Duplex Trunks use
StatMux Packet Switching
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Ex) Frame RelayCorporate Connectivity
Detroit
384 Kbps
PVC, OKC - Detroit
Carrier Frame Relay Network
OKC
576 Kbps
320 Kbps
PVC, NYC - OKC
NYC
Router
Local Carriers dedicate bandwidth to our use.
Carrier provides random Packet Switched StatMux
connectivity via PVCs.
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Ex) Frame RelayCorporate Internet Connectivity
Detroit
ISP
576 Kbps
PVC, OKC - Detroit
640 Kbps
Carrier Frame Relay Network
OKC
Router
448 Kbps
960 Kbps
PVC, NYC - OKC
NYC
OKC to FR Leased Line must handle all traffic
to/from Internet, to/from OKC corporate, and
Detroit/NYC pass-thru traffic.
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Leased Line at OKC ? FR Net

• Outbound
• OKC?Det 144
• OKC?NYC 76
• Det?NYC 28
• NYC?Det 34
• ISP?Det 100
• ISP?NYC 90

• Inbound
• Det?OKC 88
• Det?NYC 28
• Det?ISP 50
• NYC?OKC 112
• NYC?Det 34
• NYC?ISP 40

Total Outbound 472 Kbps Total Inbound 352
Kbps Leased Line Size 944 Kbps Leased Line
960 Kbps minimum.
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Frame Relay

• End-to-End DelayInternet Frame Relay
  equivalent sized Leased
  Line Network
• Cost TendencyInternet equivalent sized Leased
  Line Network

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300,000 Byte Data File

• 1460 Layer 7 Bytes per Ethernet Packet
• 205 full packets one with 700 Bytes
• 40 Bytes TCP IP
• 6 Bytes Frame Relay
• 2051506 1746 309,476 Bytes
• 2,475,808 bits / 1,536,000 bits/sec 1.612
  seconds
• Overhead 20646/309,476 3.06

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Worldwide Frame Relay Revenues
Sources Data Communications Network World
Business Communications
Projected to level off decline.
10.5B 00
12.7B 01
6.25B 98
8.00B 99
15.4B 02
0.08B 93
3.87B 97
16.7B 03
20B? 04
0.23B 94
0.65B 95
1.28B 96
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Internet Service Provider Backbone
A
Trunks
Leased Line
B
C
ISP Router
ISP Cloud Full Duplex Trunks use StatMux
Packet Switching
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THEN ISP using Frame Relay VC's for Trunk
Connections
A
ISP Router
FR Trunks
FRPVC
C
Leased Line ISP Trunk
FR Switch
B
Frame Relay Cloud
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NOW ISP using Leased Linesfor Trunk Connections
A
ISP Router
Trunks
C
Circuit
Leased Line ISP Trunk
Cross Connect Circuit Switched TDM
B
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NOW ISP using Light Wavesfor Trunk Connections
A
ISP Router
Trunks
C
Circuit
Fiber Optics ISP Trunk
Optical Switch
B
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Frame Relay Backbone
A
Trunks
Leased Line
B
C
FR Switch
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THEN FR using Leased Linesfor Trunk Connections
FR Switch
A
Trunks
C
Circuit
Leased Line ISP Trunk
Cross Connect
B
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NOW Frame Relay using MPLS VC's for Trunk
Connections
A
ISP Router
FR Switch
ISP Trunks
MPLSPVC
C
Leased Line FR Trunk
B
ISP Cloud
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Frame Relay as a Corporate Backbone...

• More Secure than the Commodity Internet
• Can move a lot of data rapidly (if you pay for
  proper CIR and burst rate)
• Is marginal for moving time sensitive traffic
• Generally Cheaper for data than Leased Lines
  Fewer access lines required Backbone has
  higher Carrying Capacity

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Commodity Internet Performance
Probability of dropped packets
Average Delay for delivered packets
0
100
Trunk Offered Load
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QoS

• DE bit used by FR switches to police network
• Traffic CIR enters switch in a 1 second
  interval? Marked DE
• If you are behaving......and other users exceed
  their CIRs......and FR switch becomes
  congested......then other users traffic gets
  dumped 1st......your traffic is protected.
• Helps shelter you from behavior of others

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Frame Relay Performance
Probability of dropped packets
Average Delay for delivered packets
0
100
Trunk Offered Load
Dashed If we are transmitting at CIR Solid
Provided we are transmitting at protection from behavior of others. Internet
priorities provide somewhat similar effect.
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ATM

• OSI Layer 2 Protocol
• Uses Cell Switching5 bytes overhead, 48 bytes
  traffic
• Capable of hauling all types of traffic
  (voice, data, video)
• Works at any speed, any distance
• Uses Virtual Circuits

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ATM

• 7 Application
• 6 Presentation
• 5 Session TCP
• 4 Transport TCP
• 3 Network IP
• 2 Data Link ATM
• 1 Physical Usually SONET

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MULTIPLEXING
StatMux
TDM
FDM
Circuit
SWITCHING
Packet
Cell
X
X
ATM uses Cell Switching
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StatMuxATM Version
Different channels use all of the frequency some
of the time, at random, as needed.
frequency
1
empty
2
Can also use TDM.
1
3
empty
time
1
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