Overview of Protocols

TCP/IP and HTTP

BSIT (Hons.), Semester-VUNIVERSITY OF EDUCATION, Bank road Campus, LahoreSanaa.po@gmail.com

TCP/IPTransmission Control Protocol / Internet Protocol

What is a Protocol?

• A protocol is a collection of rules and procedures for two computers to exchange information

• Protocol also defines the format of data that is being exchanged

What is a TCP/IP?

• TCP/IP stands for Transmission Control Protocol / Internet Protocol, developed to allow cooperating computers to share resources / Information across a network

• A highly standardized protocol used widely on the Internet

• TCP/IP protocols map to a four-layer conceptual model known as the DARPA (Defense Advanced Research Projects Agency) model 

TCP/IP Layers:

Because TCP/IP was developed prior to the OSI 7-layer mode, it does not have 7 layers but only 4 layers…

Application

Application Presentation

Session

Transport Host-to-Host/ Transport

Network Internet

Data Link Network Interface

Physical

OSI 7-layer TCP/IP Protocol Suite

Continue…

The layers of TCP/IP protocol suite contain relatively independent protocols that can be mixed & matched depending on the need of the system.

Application

Application SMTP, PTP, HTTP, DNS, SNMP, TELNET…Presentation

Session

TransportHost-to-Host/ Transport

SCTP, TCP, UDP

Network Internet / Network IP, ICMP, IGMP, RARP, ARP

Data Link Network Interface Ethernet, Token Ring,

Frame Relay, ATMPhysical

OSI 7-layer TCP/IP Protocol Suite

Network Interface Layer: (Physical & Data Link)

TCP/IP does not define any specific protocol at this layer. It supports all the standards & proprietary protocols.

– Ethernet– Token Ring– Frame Relay– ATM (Asynchronous Transfer Mode)

Internet / Network Layer: (Network)

At this layer, TCP/IP supports the Internetworking Protocols (IP) uses four supporting protocols:

– ARP (Address Resolution Protocol)

– RARP (Reverse Address Resolution Protocol)

– ICMP (Internet Control Message Protocol)

– IGMP (Internet Group Message Protocol)

Transport / H-H Layer: (Transport)

At Transport / Host-to-Host layer, TCP/IP is working with 3 Protocols that are responsible for delivery of a message from one device to another:

– UDP (User Datagram Protocol)

– TCP (Transmission Control Protocol)

– SCTP (Stream Control Transmission Protocol)

Application Layer: (Application, Presentation & Session)

This layer is equivalent to the upper three layers of OSI model:

– HTTP (Hyper Text Transfer Protocol)

– FTP (File Transfer Protocol)

– SMTP (Simple Mail Transfer Protocol)

– DNS (Domain Name System)

– RIP (Routing Information Protocol)

– SNMP (Simple Network Management Protocol)

– …

HTTPHyper Text Transfer Protocol

HTTP?

• HTTP stands for Hyper Text Transfer Protocol

• These are the rules governing the conversation between a Web client and a Web server

HTTP?

• HTTP uses the services of TCP

• HTTP itself is a stateless Protocol:

– Client and server establish TCP connection

– Client requests content

– Server responds with requested content

– Client and server close connection (usually)

WebserverWeb

server

HTTP request

HTTP response(content)

Webclient

(browser)

Webclient

(browser)

Any Question?