Transcript Document

Network Research at CTI
James Yu, Ph.D.
Assistant Professor
School of CTI
[email protected]
7/17/2015
DePaul University
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James Yu, Ph.D.
Ph.D. in Computer Science from Purdue
University, 1985
[Distinguished] Member of Technical Staff,
Bell Labs, Lucent Technologies, 1985 –
2000
Director of Network Technologies,
ARBROS Communications, 2000 – 2001
Assistant Professor, DePaul University,
2002 - now
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Research Interests
Network Performance Evaluation
Wireless Security
VoIP Traffic Engineering
Fault Tolerant Network Design
Network education: hands-on exercises
for distance learning students
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Framework of Network Research
References
Problem
Statement
Empirical
Framework
Theoretical
Model
Solutions to
The problem
Revision
Data Analysis
Comparative
Study
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Conclusion
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Network: the BIG Picture
NNI
PSTN
Access
Network
Security
Layer
Internet
ISP
Network
Network
Services and Management
Switched
Network
Transport
Network
UNI
carrier network
Security Layer
Data
LAN
Voice
Network
Data
Center
Call
Center
Security Layer
2G/3G
Network
cellular network
converged enterprise network
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Project I: Performance Analysis
Key measurement: throughput (bps) and delay (ms or s)
Ethernet Switch
IP Router
Linux
Bridge/Router
Windows
Bridge/Router
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One-way Delay (in s) on 100baseTX Link (Linux Bridge vs. Linux Router)
150
100
bridge
router
50
0
200
400
600
800
1000
1200
1400
1600
Throughput (bps) on 100BaseTX Link (Linux Bridge vs. Linux Router)
120,000,000
100,000,000
80,000,000
bridge (1M fps )
60,000,000
40,000,000
router (1M fps )
20,000,000
router (1K fps )
(20,000,000)
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0
200
400
600
800
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1000
1200
1400
1600
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Switch Performance Comparison
on Gigabit Ethernet
100.00%
90.00%
80.00%
70.00%
60.00%
100M
1000M
50.00%
40.00%
30.00%
20.00%
10.00%
0.00%
Switch
Linux
Windows
Question: could you develop a problem statement from this chart?
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Wireless Performance
60
50
Line Speed
40
UDP
TCP
30
Question: why is TCP
performance is only 50% of the
line rate for wireless
communications?
20
10
0
802.11b
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802.11g
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Project II: Wireless Denial of
Service (DoS) Research
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TCP performance under DoS
Start
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Stop
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Project III: VoIP Research
SS7
SS7
PSTN
Switch
SoftSwitch
SoftSwitch
Carrier VoIP
Network
Trunk MG
PSTN
Switch
IP (internal)
Trunk MG
Call Manager
(SIP Proxy)
Q.931
Access MG
V
IP (public)
IP (private)
Call Manager
(Enterprise)
MG: Media Gateway
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VoIP: Traffic Engineering
Design the network with sufficient capacity to meet
the traffic demand with satisfactory performance
Requirement: assurance of Voice Quality.
– If call quality cannot be assured, reject the call request.
Demand (A) - Traffic Intensity
number of calls × duration of average calls
Erlang
Resources (N) – Network bandwidth (bps) and
capacity (pps)
Grade of Service (GoS) – blocking probability
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Research Areas of VoIP
IP Multimedia Subsystem (IMS)
– How is a VoIP call from one service provider to
another service provider today?
VoIP Security
Voice Quality
Quality of Service (QoS) over internet and
intranet
Supplemental and Intelligent Network (IN)
services
API and VoXML
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Project IV: Fault Tolerant Network
RSL
RSTP (802.1w)
VRRP
Dual Homing
ISP-01
ISP-02
Network Design Goal:
1. No single point of failure
2. Failover time << 1 sec
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Project V: Remote Lab Access
Linux
Gateway
Private
Networking
Labs
Public
Internet
Windows
Terminal Server
Devices w/
Console
interface
Console
interface
Telecom
Terminal Server
Devices w/
IP interface
Problem Statement: supporting distance learning students to perform hands-on
network exercises from any place with 24×7 access to the network lab
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Conclusions
Evolution of the telecom networks and
network technologies
Convergence of PSTN and Internet
Growing demand for wireless networks
(bandwidth utilization, more bandwidth, new
applications, etc.)
Increasing threat and concerns of network
security
Higher requirements for network reliability and
service availability
New generation of devices and services
Needs: more research work
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