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Chapter 1
Data Communications and NM Overview
Chapter 1
Data Communications and
Network Management Overview
Network Management: Principles and Practices
© Mani Subramanian 2011
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Chapter 1
Data Communications and NM Overview
Objectives
• Telecommunications overview
 Data communications overview
 Evolution of converged networks
 Desktop processors and LAN technology
 Client-Server architecture in networking
 Internet and intranet
 Network communication protocols
 OSI and Internet standards
 Broadband networks and services
 Need for network management and NMS
 Operations, Administration, Maintenance, and Provisioning
 Network management architecture and organization
 Concept of Network Operations Center
 Perspectives of network management
 Network management system
 Look-ahead of network management technology
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Telephone Network
• Modern network evolution from Telephone /
Telecommunications Network
• Characteristics of Telephone network
• Reliable - does what is expected of it
• Dependable - always there when you need
it (remember 911?)
• Good quality (connection) - hearing each
other well
• Reasons for QoS:
• Good planning, design, and implementation
• Good operation and management of
network
• Migration to new technologies –
• e.g., From analog to digital technology
Notes
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Chapter 1
Data Communications and NM Overview
Telephone Network Model
Regional Center
Class 1 switch
Regional Center
Class 1 switch
Sectional Center
Class 2 switch
Sectional Center
Class 2 switch
Primary Center
Class 3 switch
Primary Center
Class 3 switch
Toll Center
Class 4 switch
Toll Center
Class 4 switch
End Office
Class 5 switch
End Office
Class 5 switch
To other
Regional centers
Sectional centers
Primary centers
Toll centers
End offices
To other
Primary centers
Toll centers
End offices
To other
Class 4 toll points
End offices
Legend:
Loop
Direct Trunk
Toll-Connecting Trunk
Voice
Voice
Toll Trunk
Figure 1.1 Telephone Network Model
Notes
• Notice the hierarchy of switches
• Primary and secondary routes programmed into switches
• Automatic routing (Failure  Alternative route)
• Where is the most likely failure?  Proactive monitoring
• Use of Operations Support Systems to ensure QoS
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Operations Support Systems / NOC
• Operations Support Systems (OSSs) help
manage the operation of networks
• OSSs in telecommunications monitor:
• Analog network parameters:
•S/N ratio, transmission loss, call blockage,
etc.
• Digital network parameters:
• Packet loss, Packet delay, Throughput,
QoS, etc.
• Real-time management of network
• Trunk (logical entity between switches / nodes)
maintenance system measures loss and S/N
Trunks not meeting QoS removed before
customer notices poor quality
• Traffic measurement systems measure call drops
and blockage. Additional switches or routers
planned to keep the call blockage or drops below
acceptable level
• OSSs distributed at central offices and customer
premises
• Network management done centrally from
Network Operations Center (NOC)
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Data and Telecommunication Network
Data communication network
Terminal
Terminal
Host
Modem
Modem
Loop
Loop
Modem
Loop
Voice
Voice
Telecommunication network
Figure 1.3 Data and Telecommunication Networks
Notes
• Computer data is carried over long distance by
telephone (telecommunication network)
• Output of telephone is analog and output of
computers is digital
• Modem is used to “modulate” and “demodulate”
computer data to analog format and back
• Clear distinction between the two networks is
getting fuzzier with modern multimedia networks
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Chapter 1
Data Communications and NM Overview
Migration to Digital Technology
Data communication network
Terminal
Terminal
Communications
controller
Host
Front end
processor
Voice
Voice
PBX
PBX
Voice
Voice
Telecommunication network
Figure 1.4 Digital Data and Telecommunication Networks
Notes
• Analog transmission migrated to digital
transmission
• Analog sources converted to digital signals
• CPE (Customer Premises equipment) included
digital PBX (Private Branch Exchanges)
• Analog bandwidth hierarchy migrated to
synchronous digital hierarchy
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Chapter 1
Data Communications and NM Overview
DCE with LAN
DCE.. Distributed Computing Environment
Workstation
Host
Workstation
Ethernet
Workstation
Host
Fgure 1.5(a) Hosts and Workstations on Local LAN
Notes
• Driving technologies for DCE:
• Desktop processor
• LAN
• LAN - WAN network
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Chapter 1
Data Communications and NM Overview
LAN-WAN Network
LAN A
LAN B
Bridge /
Router
Bridge /
Router
Bridge /
Router
LAN C
WAN
communication link
Figure 1.5(b) Remote LANs Interconnected by WAN
Notes
• Major impacts of DCE:
• No more monopolistic service provider
 Need for standards
• No centralized IT controller
• Hosts doing specialized function
• Client/Server architecture formed the core
of DCE network
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Chapter 1
Data Communications and NM Overview
Client/Server Model
Request
Control
transf er
Server
Client
Control
transf er
Response
Figure 1.6 Simple Client-Server Model
Notes
• Post office analogy; clerk the server, and the
customer the client
• Client always initiates requests
• Server always responds – waiting for requests
• Notice that control is handed over to the receiving
entity  A client can’t initiate a process in the server
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Chapter 1
Data Communications and NM Overview
Client/Server Examples
Client A
Client Z
Server
(a) Server with Multiple Clients
Client
(joe.stone)
to [email protected]
Bridge
Domain
Name
(b) Dual Role of Client-ServerServer
Mail server
Figure 1.7 Client-Server in Distributed Computing Environment
Notes
• Concurrent processing of requests by server
minimizes delay
• Cooperative computing processes (Client, Mail, DNS)
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Chapter 1
Data Communications and NM Overview
TCP/IP Based Networks
•
•
•
•
TCP/IP is a suite of protocols
Internet is based on TCP/IP
IP is Internet protocol at the network layer level
TCP is connection-oriented transport protocol
and ensures end-to-end connection
• UDP is connectionless transport protocol and
provides datagram service
• Much of the network mgmt. messages are
based on UDP/IP
• ICMP part of TCP/IP suite
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Some Protocols in TCP/IP
Suite (Stallings2000)
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Chapter 1
Data Communications and NM Overview
Internet Configuration
Workstation
(Joe)
Mail Server
Workstation
LAN A
Domain
Name
Server
LAN B
Bridge /
Router
Bridge /
Router
Bridge /
Router
LAN C
Gateway
WAN
Gateway
LAN X
Bridge /
Router
Bridge /
Router
Bridge /
Router
LAN Z
LAN Y
Workstation
PC (Sally)
Mail Server
Figure 1.8 Internet Configuration
Notes
• Walk through the scenario of email from Joe to Sally
• How is the Internet managed?  If mail doesn’t reach
destination, then where is the failure?
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Chapter 1
Data Communications and NM Overview
Architecture, Protocols and Standards
• Communication architecture
• Modeling of communication systems, comprising
• Functional components
• Operations interfaces between them
• Communication protocols
• Operational procedures
• Intra- and inter-modules
• Communication standards
• Agreement between manufacturers on protocols
of communication equipment on
• Physical characteristics
• Operational procedures
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Communication Architecture
User A
User Z
Peer-Protocol Interface
Application Layers
Application Layers
Transport Layers
Transport Layers
Physical Medium
(a) Direct Communication between End Systems
System A
Intermediate system
System Z
User A
User Z
Peer-Protocol Interface
Application Layers
Application Layers
Transport Layer
Transport Layers
Transport Layers
Conversion
Physical Medium
Physical Medium
(b) Communication between End Systems via an Intermediate System
Figure 1.10 Basic Communication Architecture
Notes
• Inter-layer interface: user and service provider
• Peer-layer protocol interface
• Role of intermediate systems
• Gateway: Router with protocol conversion as
gateway to an autonomous network or subnet
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Chapter 1
Data Communications and NM Overview
OSI Reference Model
User / Application program
Layer 7
Application
Layer 6
Presentation
Layer 5
Session
Layer 4
Transport
Layer 3
Network
Layer 2
Data link
Layer 1
Physical
Physical medium
Figure 1.11 OSI Protocol Layers
Notes
• Importance of the knowledge of layer structure
in NM
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Chapter 1
Data Communications and NM Overview
OSI Layers and Services
Layer
No.
Layer Name
Salient services provided by the layer
1
Physical
-Transfers to and gathers from the physical medium raw
bit data
-Handles physical and electrical interfaces to the
transmission medium
2
Data link
-Consists of two sublayers: Logical link control (LLC) and
Media access control (MAC)
-LLC: Formats the data to go on the medium; performs
error control and flow control
-MAC: Controls data transfer to and from LAN; resolves
conflicts with other data on LAN
3
Network
Forms the switching / routing layer of the network
4
Transport
-Multiplexing and de-multiplexing of messages from
applications
-Acts as a transparent layer to applications and thus
isolates them from the transport system layers
-Makes and breaks connections for connection-oriented
communications
-Flow control of data in both directions
5
Session
-Establishes and clears sessions for applications, and
thus minimizes loss of data during large data exchange
6
Presentation -Provides a set of standard protocols so that the display
would be transparent to syntax of the application
-Data encryption and decryption
7
Application
-Provides application specific protocols for each specific
application and each specific transport protocol system
Notes
• Importance of services offered by different layers
and the protocol conversion at different layers in NM
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Chapter 1
Data Communications and NM Overview
PDU Communication Model
End System A
User A
End System Z
User Z
UD
Application
(A) PCI
Presentation
(P) PCI
Session
(S) PCI
Transport
(T) PCI
Network
(N) PCI
Data link
(D) PCI
Application
UD
Presentation
(A) PDU
Session
(P) PDU
Transport
(S) PDU
(T) PDU
(N) PDU
Network
Data link
Physical
Physical
(D)PDU Data stream
Physical Medium
Figure 1.13 PDU Communication Model between End Systems
Notes
• What is the relevance of PDU model in NM?
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Chapter 1
Data Communications and NM Overview
OSI and Internet
OSI
INTERNET
Application
Presentation
Application Specific
Protocols
Session
Transport
SNICP
Network
Transport
Connection- Connectionless: UDP oriented: TCP
Network
IP
SNDCP
SNDAP
Data Link
Not Specified
Physical
Figure 1.17 Comparison of OSI and Internet Protocol Layer Models
Notes
• Simplicity of Internet; specifies only layers 3 and 4
• Integrated application layers over Internet
• Commonality of layers 1 and 2 - IEEE standard
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Chapter 1
Data Communications and NM Overview
Application Protocols
OSI User
Internet User
VT
TELNET
FTAM
FTP
MOTIS
SMTP
CMIP
Presentation Layer
Terminal
Application
File Transfer
Mail / Message
Transfer
Management
Application
SNMP
Transport Layer
Figure 1.18 Application Specific Protocols in ISO and Internet Models
Notes
Internet user
Telnet
OSI user
Virtual Terminal
File Transfer Protocol
File Transfer Access & Mgmt
Simple Mail Transfer
Protocol
Message-oriented Text
Interchange Standard
Simple Network
Common Management
Management Protocol Information Protocol
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Chapter 1
Data Communications and NM Overview
Broadband Network
Access
Network
WAN
CPE
Network
LAN
Cable
WLAN
DSL
HomePlug
IP
MPLS
Edge
Router
Fixed
Wireless
Bluetooth
Residential
Gateway
Mobile
Wireless
ATM
HomePNA
Cable
Satellite
UWB
PON
Firewire
Figure 1.19 Broadband Network Segments and Technologies
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Broadband Access Networks
Cable Modem
Cable
Customer
Modem
Network
HFC
Network
Cable
Modem
Head End
Business
Customers
Router/
ATM Switch
DSL
xDSL Customer
Modem
Network
Telephone
Loop
OC-n /
STS-n
Link
Central
Office
Equipment
IP / ATM
WAN
Router/
ATM Switch
Satellite Communication
BSU
Mobile
Unit
G-3
Wir
eles
s
Access
Point
Network
Terrestrial
Wireless
BSU
Fixed
Wireless
Customer
Network
Figue 1.20 Broadband Access Networks
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Centrally Managed Network Issues
INMS
EMS
EMS
EMS
Network
Element
Domain
Network
Element
Domain
Network
Element
Domain
Figure 1.21 Case History 2:
Centrally Managed Network Issues
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Some Common Network Problems
• Loss of connectivity
• Duplicate IP address
• Intermittent problems
• Network configuration issues
• Non-problems
• Performance problems
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Challenges of IT Managers
• Reliability
• Non-real/real time data integration problems
• Rapid technological advance
• Managing client/server environment
• Scalability
• Troubleshooting tools and systems
• Trouble prediction
• Standardization of operations - NMS helps
• Centralized management vs. “sneaker-net” (i.e.,
in lieu of transferrable media such as flash
drives, external hard drives, …)
Notes
Network Management: Principles and Practices
© Mani Subramanian 2011
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Chapter 1
Data Communications and NM Overview
Network Management
Network
Management
Network
Provisioning
Network
Operations
Network
Maintenance
Planning
Fault Management / Service Restoration
Fault Management
Design
Configuration Management
Trouble Ticket
Administration
Performance Management / Traffic Management
Network Installation
Security Management
Network Repairs
Accounting Management
Reports Management
Facilities Installation
& Maintenance
Inventory Management
Routine Network
Tests
Data Gathering & Analyses
Figure 1.22 Network Management Functional Groupings
Notes
• OAMP
• Operations
• Administration
• Maintenance
• Provisioning
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
NM Functional Flow Chart
Network
Users
Configuration Data
Management
Decision
Performance & Traffic Data
New
Technology
Engineering Group
- Network Planning &
Design
TT Restoration
Operations Group
NOC
I & M Group
-Network Installation &
Maintenance
- Network Operations
Fault TT
Installation
Figure 1.23 Network Management Functional Flow Chart
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
NM Components
NMS
Network
Agent
Network
Agent
Network
Objects
Network
Objects
Figure 1.25 Network Management Components
Notes
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Interoperability
NMS
Vendor A
Messages
Services & Protocols
NMS
Vendor B
Network
Agent
Network
Agent
Network
Agent
Network
Agent
Network
Objects
Network
Objects
Network
Objects
Network
Objects
Figure 1.26 Network Management Interoperability
Notes
• Message exchange between NMSs managing
different domains
Network Management: Principles and Practices
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Chapter 1
Data Communications and NM Overview
Status and Future Trends
• Status:
• SNMP management
• Limited CMIP management
• Operations systems
• Polled systems
• Current Focus:
• Object-oriented approach
• Service and policy management
• Business management
• Web-based client management
• Future Trends
• Web-based management?
• XML based management
Notes
Network Management: Principles and Practices
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