Lec4: TCP/IP, Network management model, Agent architectures

Organized by: Nada AlhirabiNET 311

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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• Exchange of data between end systems• Error free• In sequence• No losses• No duplicates• Quality of service

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OSI Layers• Session

• 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.

• Application layer• Transport layer• Internet layer (or Network Layer)• Network access layer (or Link Layer)• Physical layer

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TCP/IP Protocol Architecture

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TCP/IP Protocols

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OSI vs. TCP/IP

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

Workstation

The Internet

InternetRouter

LocalRouter

Workstation

Lab

Configure the workstation for Internet access by Installing TCP/IP.

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

Choose Network/Properties

Install Protocol

Choose TCP/IP

Start

End

From NetworkNeighborhood/Properties.

Add

OK

TCP/IPprotocolinstalled.

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

Choose Network

TCP/IP/Properties

Start

From NetworkNeighborhood/Properties.

Define TCP/IP properties

Proceed

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

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NM

Network Resource

Network Management systemNM

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Network ManagementConfiguration• Centralized vs

distributed• Centralized

configuration

Probe = Remote Monitor NMS = Network Management System WS = Workstation

LAN 1

Node 1

Backbone Node

Hub Agent

WS Agent

Probe Agent

Router Agent

Router Agent

WS Agent

Probe Agent

LAN 2

Node 2

Router Agent

Probe Agent

WS Agent

LAN 3

Node 3

NMS

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Network ManagementConfiguration

• Centralized configuration• One management station hosts NMS• Remote monitors/probes on LAN segments

• Advantage: NMS has complete view• Disadvantage: single point of failure

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:• Open view (hp)• Cisco

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NM

NM NM

Network Resource

Network Management systemNM

B. Hierarchical Model (Cont.)

• Advantages:1. Distributing the load of the network.2. Distributing the load of managing the network.3. Bringing the network management systems closer to the managed

network resources• Disadvantages:

1. High cost.2. 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)

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NM

NMNM

NM

Network Management systemNM

Network ManagementConfiguration• 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

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Network ManagementConfiguration• Distributed

configuration

Probe = Remote Monitor NMS = Network Management System WS = Workstation -------- = In-band or out-of band management communication

NMS

Probe Agent

WS Agent

LAN 3 Node 3

Router Agent

NMS

Backbone

Router Agent

WS Agent

Probe Agent

LAN 2 Node 2

NMS

LAN 1

Node 1

Hub Agent

WS Agent

Probe Agent

Router Agent

NMS

C. Distributed Management Model (Cont.)

• Advantages:1. Distributing the load on the entire network completely.2. Easy to expand the network.3. Reliable and consistent.

• Disadvantages:1. Very complicated.2. International standards are not yet defined.3. Low security.

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Network Management Model

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Manager

Agent

MIB

Managed Entity

AlertsInstructions

Management Stations

Resources

Management Information 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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