Transcript Lec4_ NET 311

Organized by: Nada Alhirabi
NET 311
Lec4: TCP/IP, Network
management model, Agent
architectures
Protocol Architecture
• A protocol architecture is the layered structure of
hardware and software that supports the exchange
of data between systems and supports distributed
applications, such as electronic mail and file transfer.
• At each layer of a protocol architecture, one or more
common protocols are implemented in
communicating systems. Each protocol provides a
set of rules for the exchange of data between
systems.
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OSI Reference Model
• OSI: Open System Interconnection
• A 7-layer model
• Each layer performs a subset of the required
communication functions
• Each layer relies on the next lower layer to perform
more primitive functions
• Each layer provides services to the next higher layer
• Changes in one layer should not require changes in
other layers
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OSI Reference Model
• Application: supporting network
applications - FTP, SMTP, HTTP, etc.
• Presentation: handle different data
representations (e.g., encryption)
• Session: connections between apps
• Transport: host-host - TCP, UDP
• Network: routing of datagrams from
source to dest - IP, routing protocols
• Link: data transfer between adjacent
network elements - PPP, Ethernet
• Physical: bits “on the wire”
Application (7)
Presentation (6)
Session (5)
Transport (4)
Network (3)
Data link (2)
Physical (1)
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OSI Layers
• Physical
• Physical interface between devices
• Mechanical
• Electrical
• Functional
• Procedural
• Data Link
• Means of activating, maintaining and deactivating a reliable
link
• Error detection and control
• Higher layers may assume error free transmission
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OSI Layers
• Network
• Transport of information
• Higher layers do not need to know about underlying
technology
• Not needed on direct links
• Transport
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Exchange of data between end systems
Error free
In sequence
No losses
No duplicates
Quality of service
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OSI Layers
• Session
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Control of dialogues between applications
Dialogue discipline
Grouping
Recovery
• Presentation
• Data formats and coding
• Data compression
• Encryption
• Application
• Means for applications to access OSI environment
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TCP/IP Protocol Architecture
• Developed by the US Defense Advanced
Research Project Agency (DARPA) for its packet
switched network (ARPANET)
• Used by the global Internet
• No official model but a working one.
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Application layer
Transport layer
Internet layer (or Network Layer)
Network access layer (or Link Layer)
Physical layer
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COMP4690, by Dr Xiaowen Chu,
HKBU
TCP/IP Protocol Architecture
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COMP4690, by Dr Xiaowen Chu,
HKBU
TCP/IP
Protocols
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COMP4690, by Dr Xiaowen Chu,
HKBU
OSI vs. TCP/IP
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TCP/IP
• An important protocol used widely on the
Internet
• A routable protocol
• Supports communication with UNIX networks or
any other network that work under the TCP/IP
protocol
• The base protocol in UNIX networks is TCP/IP
• Can be used for configuring peer-to-peer as well
as client-server networks of very large scale
A TCP/IP Application Scenario
Lab
Workstation
Internet
Router
Local
Router
Workstation
Configure the workstation for Internet access by
Installing TCP/IP.
The
Internet
Module
Basic TCP/IP Installation and Configuration
TCP/IP Installation and
Configuration
• A two-step process
• First, install the protocol
• With many modern OSs such as Windows XP, it is
automatically installed
• Second, configure its properties
• When TCP/IP is automatically installed, the properties
are set to be obtained from a DHCP server
• However, it is also possible to manually set the
properties
TCP/IP Installation Steps
Start
From Network
Neighborhood/
Properties.
Choose Network/
Properties
TCP/IP
protocol
installed.
Install Protocol
Add
OK
Choose TCP/IP
End
Accessing the Window for
TCP/IP Properties
• Under different Windows operating systems the
TCP/IP properties are accessed in different ways
• The best and the most consistent way to access TCP/IP
properties Windows is to go through the Control Panel
and then select the Network Icon
• Another way to access the properties is to go through
Network Neighborhood
• Thereafter, select the network properties (Based on
the NIC) and then then continue to select the TCP/IP
properties
Accessing TCP/IP Properties
Tab
Start
From Network
Neighborhood/
Properties.
Choose Network
TCP/IP/
Properties
Proceed
Define TCP/IP properties
Network Models
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Architectural models for network
management
• Network management architecture consists of three sections:
A.
Centralized:
• Consists of a key management station.
B.
Hierarchical :
• Consists of one main station at the center and various management
stations distributed among the systems.
C.
Distributed:
• Consists of various stations for network management
• Distributed based on the geographic distance or function.
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A. Centralized Management
Model
• It is defined as a single network management system that
runs network management applications and all the
information are stored in a single centralized database.
• Examples:
• Open view (hp)
• net view (IBM)
• Sepctrum
NM
Network Management system
Network Resource
NM
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Network Management
Configuration
LAN 1
Node 1
Hub
Agent
WS
Agent
Probe
Agent
Router
Agent
NMS
Backbone Node
WS
Agent
Router
Agent
Probe
Agent
WS
Agent
Router
Agent
LAN 2
LAN 3
Node 2
Node 3
Probe = Remote Monitor
NMS = Network Management System
WS = Workstation
Probe
Agent
COMP4690, by Dr Xiaowen Chu,
HKBU
• Centralized vs
distributed
• Centralized
configuration
Network Management
Configuration
• Centralized configuration
• Advantage: NMS has complete view
• Disadvantage: single point of failure
COMP4690, by Dr Xiaowen Chu,
HKBU
• One management station hosts NMS
• Remote monitors/probes on LAN segments
Advantages of the Centralized
Management Model
1.
Facilitates decision making.
2.
Only single place is determined for network management.
3.
Easy access to the centralized database.
4.
Easy to expand and maintain the network.
5.
Highly secure.
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Disadvantages of the Centralized
Management Model
1.
In the case of failure in the network management, all the
related network management systems will fail.
2.
Overloading the network management system due to the
large amount of the exchanged information.
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B. Hierarchical model
• Hierarchical model is defined as a single network
management system that manages various smaller
network management systems that control network
resources.
• Examples:
NM
• Open view (hp)
• Cisco
NM
NM
NM
Network Management system
Network Resource
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B. Hierarchical Model (Cont.)
• Advantages:
1.
2.
3.
•
Distributing the load of the network.
Distributing the load of managing the network.
Bringing the network management systems closer to the managed
network resources
Disadvantages:
1.
2.
High cost.
Complicated and difficult in connection.
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C.
Distributed Management Model
• In this model network management systems are
distributed on different indeterminate and in
dependable places.
• Examples:
• CORBA(NCR)
• DCOM(Microsoft)
NM
Network Management system
NM
NM
NM
NM
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Network Management
Configuration
• Distributed configuration
• Each LAN has its own management station and a simple NMS
• One mgmt station/NMS manages the backbone and coordinates
local NMSs
• Advantage: robust in case of failure
• Disadvantage: complexity, coordination
Network Management
Configuration
• Distributed
configuration
LAN 1
WS
Agent
Probe
Agent
Router
Agent
NMS
Node 1
NMS
Backbone
WS
Agent
Router
Agent
LAN 2
Probe
Agent
NMS
Node 2
Probe = Remote Monitor
NMS = Network Management System
WS = Workstation
-------- = In-band or out-of band
management communication
WS
Agent
Router
Agent
LAN 3
Probe
Agent
NMS
Node 3
COMP4690, by Dr Xiaowen Chu,
HKBU
Hub
Agent
C.
Distributed Management Model (Cont.)
• Advantages:
1.
2.
3.
•
Distributing the load on the entire network completely.
Easy to expand the network.
Reliable and consistent.
Disadvantages:
1.
2.
3.
Very complicated.
International standards are not yet defined.
Low security.
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Network Management Model
Manager
Instructions
Management Stations
Alerts
Agent
Managed Entity
MIB
Resources
Management Information 32
Base
Network Management Model (Cont.)
• Manager: A program that receives alerts from
agents and sends instructions to them.
• Agents: A functional unit (Programs) located
inside the managed devices (network resources)
and provide management information to the
devices and receives instructions to reconfigure
the devices.
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Network Management Model (Cont.)
• Managed Entity: The network devices (resources) that is
managed and controlled.
• Management Information Base (MIB): A database of
managed entities (resources) in the network and how
they are accessed.
• Example:
• Remote Monitoring (Rmon)
• One of the most famous MIBs (management information bases)
• Used to monitor all the different components of LAN networks
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