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LECTURER SLIDES

NETWORK PROTOCOLS

Department of Electrical Engineering

Faculty of Engineering

University of Hasanuddin

2009



OSI Reference Model

Being able to connect networks and disparate systems one

standard method. 1978 the ISO released an architecture

Revised in 1984 international standards for networked

commun ca on, ca e e e erence o e . The OSI model presents a layered approach to networking.

The OSI model :

Simplified how network hardware and software work together

Eased troubleshooting woes by providing a specific method for how

components should function.



OSI Reference Model

Application layer :

Provides a set of interfaces for applications to use togain access to networked services.

Presentation layer:

Converts data into a generic format for networktransmission; for incoming messages, it converts data toa format that the receiving application can understand.

Session layer:

Enables two parties to hold ongoing communications

Transport layer:

Manages the transmission of data across a network.



OSI Reference Model

Network layer

Handles addressing messages for delivery

Translates logical network addresses and names into

their physical counterparts.

Data Link layer:

Sends special data frames from the Network layer to

the Physical layer.

Physical layer converts :

Bits into signals for outgoing messages

Signals into bits for incoming messages.



OSI Reference Model



Application Layer (Top Layer)

Allows access to network services (networked

file transfer, message handling, anddatabase query processing)that support

.

Controls general network access, flow control,

and error recovery for applications when

appropriate.



Presentation Layer Manages data-format information for networked

communications

Converts outgoing messages into a generic format

Converts incoming messages from that generic formatinto one that makes sense to the receiving application

Protocol conversion, data encryption and decryption,graphics commands, compression and decompressionfunctions.

Software called a redirector operates: interceptsrequests for service and redirects requests thatcannot be resolved locally to the networked resourcethat can handle them.



Session Layer Hold ongoing communications, means applications on

each end of the session are able to exchange data forthe duration of the session

Manages session setup, information or message

exc anges Tear-down when the session ends

Identification only designated parties can

participate in the session Handles security services for controlling access to

session information



Session Layer Furnishes synchronization services between tasks at

each end of the session Places checkpoints in the data stream so if

communications fail, only data after the most recent

c ec point nee to e retransmitteManages issues such as who may transmit data at a

certain time and for how long

Maintains a connection through transmission ofmessages that keep the connection active



Transport Layer Manages the flow control of data between parties

across network by segmenting long streams of data intochunks adhere to the maximum packet size for thenetworking medium in use

Provides error checks to uarantee error-free data

delivery Resequences chunks back into the original data when it

is received

Provides acknowledgment of successful transmissions Responsible for requesting retransmission if some

packets do not arrive error-free



Network Layer Addresses messages for delivery

Translates logical network addresses and names intotheir physical equivalents

Decides how to route transmissions between computers,

how to get data from one point to the next Considers other factors, such as quality of service

information, alternative routes, and delivery priorities

Handles packet switching, data routing, and networkcongestion control



Data Link Layer Handles special data frames between the Network

and Physical layers. Packages raw data from the Physical layer into

data frames for deliver to the Network la er

(receiving End) A data frame is the basic unit for network traffic as

data is sent across the network medium; it is a highly

structured format in which data from upper layers isplaced for sending, and from which data from upper

layers is taken on receipt.



Physical Layer Converts bits into signals for outgoing messages, and

signals into bits for incoming ones Arranges the transmission of a data frame’s bits when

they are dispatched across the network

Manages the interface between a computer and thenetwork medium

Instructs the driver software and the network interface

as to what needs to be sent across the medium.



Standardized Network Communication

IEEE 802 specs defined how network adapters access and transmitinformation over the network cable:

802.1 Internetworking 802.2 Logical Link Control (LLC)

802.3 Carrier-Sense Multiple Access with Collision Detection (CSMA/CD) LANs(Ethernet)

.

802.5 Token Ring LAN 802.6 Metropolitan Area Network (MAN)

802.7 Broadband Technical Advisory Group

802.8 Fiber Optic Technical Advisory Group

802.9 Integrated Voice and Data Networks 802.10 Network Security

802.11 Wireless Networks

802.12 Demand Priority Access LAN, 100BaseVG-AnyLAN



802 Specs within OSI Model



Data Link Layer (802 Specs)

Logical Link Control (LLC) : For error correction and flow

control Media Access Control (MAC):

For access control The Logical Link sublayer (as defined by 802.2)

-

Defines the use of logical interface points, called Service AccessPoints (SAPs), that other computers can use to transfer information

from the LLC sublayer to the upper OSI layers.

Provides shared access for multiple NIC s with the Physical layer.

Responsible for ensuring error-free data transmission between

computers on a network Direct communication with a

computer’s NIC



Up & Down the Protocol Stack

A protocol suite, also called a stack, is a

combination of protocols that work together toachieve network communication.

Three sections that ma to the OSI model:

Network

Transport

Application



Network Protocol

Provide the following services:

Addressing and routing information Error checking

Re uestin retransmissions

Establishing rules for communicating in a particularnetworking environment called link services



Network Protocol

Samples popular Network Protocols:

DDP (Delivery Datagram Protocol) Apple’s datatransport protocol that is used in AppleTalk

IP (Internet Protocol) Part of the TCP/IP protocol suite

IPX (Internetwork Packet Exchange) and NWLinkNovell’s NetWare protocol (and Microsoft’simplementation of this protocol, respectively) used for

packet routing and forwarding NetBEUI Developed by IBM and Microsoft, it provides

transport services for NetBIOS



Transport Protocol

Responsible for ensuring reliable data deliverybetween computers



Transport Protocol

Samples popular Transport Protocols: ATP (AppleTalk Transaction Protocol) and NBP (Name

Binding Protocol) AppleTalk’s session and data transportprotocols

NetBIOS/NetBEUI NetBIOS establishes and manages;

transport services for that communication SPX (Sequenced Packet Exchange) and NWLink Novell’s

connection- oriented protocol that is used to guarantee datadelivery (and Microsoft’s implementation of this protocol)

TCP (Transmission Control Protocol) The portion of theTCP/IP protocol suite that is responsible for reliable deliveryof data



Application Protocol

Responsible for application-to-application services.



Application Protocol

Samples popular Application Protocols: AFP (AppleTalk File Protocol) Apple’s remote file

management protocol FTP (File Transfer Protocol) Another member of the TCP/IP

protocol suite that is used to provide file transfer services

NCP (NetWare Core Protocol) Novell’s client shells andredirectors

SMTP (Simple Mail Transport Protocol) A member of theTCP/IP protocol suite that is responsible for transferringemail

SNMP (Simple Network Management Protocol) A TCP/IPprotocol that is used to manage and monitor networkdevices



Protocol

Something that must be met on a protocol to beused for any type of communication to take place.



Protocol

Some common protocol used today:

NetBEUI TCP/IP

A leTalk

APPC

X.25

HDLC

XNS



Protocol

NetBEUI

A simple network layer transport protocol

Developed to support NetBIOS networks.

Like NetBIOS, NetBEUI is not routable, so it really has no place on anenterprise network.

NetBEUI is the fastest transport protocol available to NT. It’s great for fast transmission, but is not usable across routed

networks.

Benefits of NetBEUI include: speed, good error protection, ease of

implementation, and low memory overhead. Some disadvantages are: not routable, very little support for cross-

platform applications, and very few troubleshooting tools available.



Protocol

TCP/IP

The most widely used protocol suite TCP/IP is able to span wide areas and is very flexible.

Provides cross-platform support & routing capabilities

Support for the Simple Network Management Protocol(SNMP), the Dynamic Host Configuration Protocol(DHCP), the

Windows Internet Name Service (WINS), the Domain Name

Service (DNS), and a host of other useful protocols.

However, TCP/IP’s rich set of features are provided at theexpense of additional overhead, which may make it too

cumbersome for some networks or applications.



Protocol

AppleTalk

Used for communication with Macintosh computers. By enabling AppleTalk, will allow Mac clients to store

and access files located on an NT Server, print to NT

printers, and vice versa. An item of note: Must first install the NT Services For

Macintosh before you can install AppleTalk.

Mac support is only available from an NTFS partition.



Protocol

APPC

The Advanced Program-to-Program Communication(APPC) protocol

Developed by IBM

A peer-to-peer protocol used in IBM’s Systems NetworkArchitecture (SNA) for use on AS/400-series computers.



Protocol

X.25

A set of wide-area protocols that are used in packet-switching networks.

Created to connect remote terminals to mainframes.

Many other wide-area communications types areavailable in the United States, X.25 is still widely used

in Europe.



Protocol

High-level Data Link Control (HDLC)

A flexible, bit-oriented data link protocol that is basedon IBM’s Synchronous Data Link Control (SDLC).

Has been standardized by the ISO

Support half- or full-duplex transmission, circuit- orpacket-switched networks, peer-to-peer or client/server

network topologies and transmission over cable or

wireless media.



Protocol

The Xerox Network System (XNS)

Created by Xerox for use in Ethernet networks Basis for Novell’s IPX/SPX, but it is seldom found in

today’s networks.



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