COMMUNICATION PROTOCOL

Function of Protocol in Network Communication The importance of protocols and how they are

used to facilitate communication over data networks A protocol is a set of predetermined rules A standard is a process or protocol that has been endorsed by the

networking industry and ratified by a standards organization

The Role of Protocol

Networking protocols suites describe processes such as:

The format or structure of the message The process by which networking devices share

information about pathways with other networks How and when error and system messages are

passed between devices The setup and termination of data transfer

sessions

Benefit Of Using Layered Model

To visualize the interaction between various protocols, it is common to use a layered model.

There are benefits to using a layered model to describe network protocols and operations. Using a layered model: Assists in protocol design, because protocols that operate at a specific

layer have defined information that they act upon and a defined interface to the layers above and below.

Fosters competition because products from different vendors can work together.

Prevents technology or capability changes in one layer from affecting other layers above and below.

Provides a common language to describe networking functions and capabilities.

Protocol and Reference Model

There are two basic types of networking models: protocol models reference models.

Protocol Model

A protocol model provides a model that closely matches the structure of a particular protocol suite.

The hierarchical set of related protocols in a suite typically represents all the functionality required to interface the human network with the data network.

The TCP/IP model is a protocol model because it describes the functions that occur at each layer of protocols within the TCP/IP suite.

Reference Model

A reference model provides a common reference for maintaining consistency within all types of network protocols and services.

A reference model is not intended to be an implementation specification or to provide a sufficient level of detail to define precisely the services of the network architecture.

The primary purpose of a reference model is to aid in clearer understanding of the functions and process involved.

The Open Systems Interconnection (OSI) model is the most widely known internetwork reference model. It is used for data network design, operation specifications, and troubleshooting.

TCP/IP and OSI models are the primary models used when discussing network functionality, designers of network protocols, services, or devices can create their own models to represent their products.

Ultimately, designers are required to communicate to the industry by relating their product or service to either the OSI model or the TCP/IP model, or to both.

TCP/IP MODEL

OSI MODEL

Initially the OSI model was designed by the International Organization for Standardization (ISO) to provide a framework on which to build a suite of open systems protocols.

The vision was that this set of protocols would be used to develop an international network that would not be dependent on proprietary systems.

Model Seven Layer OSI

Wire (Network Cable)

Application Program

Layer 7

Layer 6

Layer 5

Layer 4

Layer 3

Layer 2

Layer 1

Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Datalink Layer

Physical Layer Berhub dg sinyal elektrik

Menyediakan koneksi point-to-point handal

Koneksi/pemgiriman paket ke tujuan

Menyediakan koneksi end-to-end

Manage koneksi end-to-end

Data filters (compression, encryption)

Interface ke program user

signals

Tujuan

NIC

Layer 1: Physical Layer

Fungsi Utama: Berhubungan dg sinyal elektrik

Contoh: • Manchester Signal Encoding

• NRZI Signal Encoding

• Bipolar-AMI Signal Encoding

Mendefinisikan bagaimana sinyal direpresentasikan

• Interpretasi sinyal elektrik, representasikan sbg 1 atau 0

Model Seven Layer OSI

Layer 2: Data Link Layer

• Deteksi dan koreksi error sinyal, jika ada

Fungsi Utama:

• Meneruskan/Forward sinyal yg diterima ke network layer

• Jika error tdk dp dikoreksi, memberikan error warning ke network layer

• Menyediakan Media Access Control (MAC)

- Utk “shared” network, kontrol siapa yg dp menggunakan network

Contoh penggunaan bersama Network:

Ring Bus Star (=hub)

Model Seven Layer OSI

Layer 3: Network Layer

Fungsi Utama:

• Best effort delivery service

- Translasi address

- Meroutekan paket dari sumber ke tujuan

Model Seven Layer OSI

Layer 4: Transport Layer

Fungsi Utama:

• Deteksi dan koreksi error paket (error control) utk E2E

• Melaksanakan flow control

- Jika penerima ingin slow down, mengurang laju transmisi TX

- Jika network congesti, mengurang laju transmisi

congestion control Layer 5: Session Layer

Fungsi Utama:

• Establish/Manage/Delete koneksi (E2E)

• Kontrol Full-Duplex/Half-Duplex

• QoS (specifikasi toleransi delay maximum)

Model Seven Layer OSI

Layer 6: Presentation Layer Fungsi Utama: Encryption, compression, dll

Presentation Layer

Encrypted Data

Raw Data

Encryption

Presentation Layer

Compressed Data

Raw Data

Compression

Fungsi Utama: Interface ke application programs

Layer 7: Application Layer

Contoh: Network API (Application Program Interface)

Model Seven Layer OSI

Model Seven Layer OSI - Summary

Bagaimana Data Mengalir?

End-to-End dan Point-to-Point

Host A Host B

Intermediate Routers

Point-to-point

NIC

End-to-end

Sekian