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1Need for network management is illustrated by its importance in
Telephone Networks
D. Karvelas
Data Communications and Network Management Overview
Telephone Network Characteristics Reliable does what is expected
of it Dependable - always there when you need it Good Quality for
connections anywhere in the world
Reasons Good Planning, Design, and Implementation Network
Management (NM)
Most of NM is so automated that it becomes part of the
operations
D. Karvelas
Telephone Network Model
Regional CenterClass 1 switch
Sectional CenterClass 2 switch
Primary CenterClass 3 switch
Toll CenterClass 4 switch
End OfficeClass 5 switch
Regional CenterClass 1 switch
Sectional CenterClass 2 switch
Primary CenterClass 3 switch
Toll CenterClass 4 switch
End OfficeClass 5 switch
Voice Voice
To otherRegional centersSectional centersPrimary centersToll
centersEnd offices
To otherPrimary centersToll centersEnd offices
To otherClass 4 toll pointsEnd offices
Legend:LoopDirect TrunkToll-Connecting TrunkToll Trunk
Addison-Wesley, Network Management, M. Subramanian
Trunk: a logical link between two switches that may traverse one
or more physical links
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2Operations Support Systems ensure QoS
A Traffic Measurement System monitors traffic Reports to a NM
system upon congestion detection
A Trunk Maintenance System monitors S/N ratioIf S/N unacceptable
trunk is removed
A Network Operations Center (NOC) oversees network operation for
a given region- It conducts centralized NM- Service restoration is
the primary objective
D. Karvelas
NM functions need to be included in componentsNetwork component
designs must include NM functions as part of their requirements and
specifications
Standardization to support interoperabilityExtremely important
for computer communicationsindustry which is multi-vendor
oriented
Centralized NM Requirements
D. Karvelas
Evolution of Communication Networks
Initially, the term Telecommunication Network was used for the
Telephone NetworkA circuit switched network accessed by any
user
The advent of computers introduced the term Data (or Computer)
Communication NetworkEnables terminal-to-host or host-to-host
communication
Telecommunications infrastructure was and is still used for Data
Communications
D. Karvelas
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3Data and Telecommunication Networks
Terminal
Modem
Voice
Terminal
Modem Modem
Voice
Host
Data Communication Network
Telecommunication network
Loop Loop Loop
Addison-Wesley, Network Management, M. Subramanian
Terminal
CommunicationsController
Front EndProcessor
Host
Data Communication Network
Telecommunication Network
Loop Loop
Terminal
Public Switch
Voice VoicePublic Switch
Enterprise Communication Environment
Addison-Wesley, Network Management, M. Subramanian
Ethernet
Workstation
Workstation
Host
Host
Workstation
(a) Hosts and Workstations on Local LAN
Distributed Computing Environment
Addison-Wesley, Network Management, M. Subramanian
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4Client Server
Client-Server Model
Distributed Computing Environment
Request
Response
Addison-Wesley, Network Management, M. Subramanian
Client A Client Z
Server
(a) Server with Multiple Clients
Client-Server Model
Addison-Wesley, Network Management, M. Subramanian
Client(joe.stone)
DomainNameServer
Mail server
(b) Dual Role of Client-Server
Bridge
to [email protected]
Client-Server Model
Addison-Wesley, Network Management, M. Subramanian
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5LAN A LAN B
LAN C
Bridge /Router
Bridge /Router
Bridge /Router
WANcommunication link
Distributed Computing Environment
(b) Remote LANs connected by a WAN
Addison-Wesley, Network Management, M. Subramanian
TCP/IP-Based Networks TCP/IP is a suite of protocols TCP/IP
protocols enable internetworking Internet is based on TCP/IP IP is
the Internet protocol at the network layer
- Uniquely identifies a host in the Internet- Offers a
connectionless and unreliable service
TCP/UDP are the Internet Transport Layer protocols- Identify the
transmitting/receiving process within a host- TCP: connection
oriented and reliable- UDP: connectionless and unreliable- Net
Management messages use UDP/IPD. Karvelas
Internet Configuration
Addison-Wesley, Network Management, M. Subramanian
WAN
LAN A LAN B
LAN C
Bridge /Router
Bridge /Router
Bridge /Router
Mail ServerWorkstation
Gateway
DomainNameServer
Workstation(Joe)
LAN Y LAN Z
LAN X
Bridge /Router
Bridge /Router
Bridge /Router
Workstation
Mail Server
Gateway
PC (Sally)
[email protected]
[email protected]
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6Architecture, Protocols, and Standards Architecture describes
basic structure of a system
- Shows its functional components - Shows the relationship among
them
Communication Network Architecture- Functional components of the
network- Interfaces among them- Protocols specify the intra-module
and inter-module
operational procedures Standardization is fundamental for
interoperability
Standardization of protocols involves agreement in the physical
characteristics and operational procedures of communication
equipment that performs similar functions.
D. Karvelas
User A
Application Layers
Transport Layers
User Z
Application Layers
Transport Layers
Physical Medium
Peer-Protocol Interface
(a) Direct Communication between End Systems
Basic Communication ArchitectureConsists of two broad set of
layers Application Layers Transport Layers
Addison-Wesley, Network Management, M. Subramanian
User A
Application Layers
Transport Layers
User Z
Application Layers
Transport Layers
Physical Medium
Peer-Protocol Interface
(b) Communication between End Systems via an Intermediate
System
Transport Layer
Conversion
System A Intermediate system System Z
Physical Medium
Basic Communication Architecture
Addison-Wesley, Network Management, M. Subramanian
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7User / Application program
ApplicationLayer 7
PresentationLayer 6
SessionLayer 5
TransportLayer 4
NetworkLayer 3
Data linkLayer 2
PhysicalLayer 1
Physical medium
OSI Reference Model
Addison-Wesley, Network Management, M. Subramanian
D. Karvelas
Domain of Responsibility for each Layer
process A ApplicationPresentationSessionTransportNetworkData
link
host2
Host 1
host3
Data linkNetwork
host4 host5
process BApplication
TransportNetworkData link
Host 6
PresentationSession
Router
net1 net2
LayerNo.
Layer Name Salient services provided by the layer
1 Physical -Transfers to and gathers from the physical medium
rawbit data-Handles physical and electrical interfaces to
thetransmission medium
2 Data link -Consists of two sublayers: Logical link control
(LLC) andMedia access control (MAC)-LLC: Formats the data to go on
the medium; performserror control and flow control-MAC: Controls
data transfer to and from LAN; resolvesconflicts with other data on
LAN
3 Network Forms the switching / routing layer of the network4
Transport -Multiplexing and de-multiplexing of messages from
applications-Acts as a transparent layer to applications and
thusisolates them from the transport system layers-Makes and breaks
connections for connection-orientedcommunications-Flow control of
data in both directions
5 Session -Establishes and clears sessions for applications,
andthus minimizes loss of data during large data exchange
6 Presentation -Provides a set of standard protocols so that the
displaywould be transparent to syntax of the application-Data
encryption and decryption
7 Application -Provides application specific protocols for each
specificapplication and each specific transport protocol system
OSI Layers and Services
Addison-Wesley, Network Management, M. Subramanian
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8PDU Communication Model between End Systems
User A
Application
End System A
Physical Medium
Presentation
Session
Transport
Network
Data link
Physical
User Z
Application
End System Z
Presentation
Session
Transport
Network
Data link
Physical
UD(A) PCI
(P) PCI (A) PDU
(S) PCI (P) PDU
(T) PCI (S) PDU
(N) PCI (T) PDU
(D) PCI (N) PDU
UD
(D)PDU Data stream
Addison-Wesley, Network Management, M. Subramanian
PCI: Protocol Control Information
Sublayer Structure of Data Link Layer
Logical Link Control(LLC)
Medium Access Control(MAC)
Network
Physical How to access a shared medium CSMA/CD, Token Ring,
FDDI, etc.
Logical Link Control
Medium Access Control
Flow Control Error Control
D. Karvelas Addison-Wesley, Network Management, M.
Subramanian
Sublayer Structure of Network Layer
SNICP
Transport
Data Link
SNDCP
SNDAP
SNICP: Sub-Network Independent Convergence ProtocolSNDCP:
Sub-Network Dependent Convergence ProtocolSNDAP: Sub-Network
Dependent Adapter Protocol
Addison-Wesley, Network Management, M. Subramanian
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9Gateway Communication to Proprietary Subnetwork
SNICP
SNDCP
SNDAP
Transport
Data link
SNICP
SNDCP-SN
SNDAP-SN
Transport
Data link-SN
SNDCP-SN
SNDAP-SN
Transport
Data link
SNICP
SNDCP
SNDAP
Physical-SN
Data link-SN
Physical Physical-SNPhysical
Subnetwork MediumNetwork Medium
System A Gateway System N Subnet system N1
N ZA
N1 N2
N3
DTE-N1
DTE-A
A-N-Z Standard NetworkN-N1-N2-N3 Subnetwork under Node N
(a) Network configuration
(b) Protocol CommunicationAddison-Wesley, Network Management, M.
Subramanian
Comparison of OSI, Internet, and SNA Models
Application
Presentation
Session
Transport
Network
SNICP
SNDCP
SNDAP
Data Link
Physical
Application SpecificProtocols
TransportConnection-less: UDP
Connection-oriented: TCP
NetworkIP
Not SpecifiedPhysical
Data Link
Path Control
Transmission Control
Data Flow Control
Presentation Services
End User Application
SNA OSI INTERNET
Addison-Wesley, Network Management, M. Subramanian
OSI User
VT
FTAM
MOTIS
CMIP
Presentation Layer
SNMP
SMTP
FTP
TerminalApplication
File Transfer
Mail / MessageTransfer
ManagementApplication
Transport Layer
TELNET
Internet User
Application Protocols in OSI and Internet Models
Addison-Wesley, Network Management, M. Subramanian
VT: Virtual TerminalFTAM: File Transfer Access and
ManagementMOTIS: Message-Oriented Text Interchange StandardCMIP:
Common Management Information Protocol
TELNET: TErminaL NETworkFTP: File Transfer ProtocolSMTP: Simple
Mail Transfer ProtocolSNMP: Simple Network Management Protocol
