Need of Protocol

The need for a protocol

A set of rules is needed for any means of communication:

• Human intercommunication (in pairs or larger groups) requires rules of conversation (do not speak if someone else is speaking) to function effectively.
• Computers are no different. Consider the following simplistic analogy:
  • Two computers connected via a single connection -- Imagine two people talking via two tin cans connected via piece of string:
    If the two people talk at the same time then we get what is known (in networking terms) as data collision.

• Therefore, we need regulations and rules to how we communicate over a computer network. For example to remote login (telnet), FTP or email.
• The set of rules and regulations is called a Protocol.

Connection Oriented and Connectionless Services

Connection Oriented and Connectionless Services

These are the two services given by the layers to layers above them. These services are :

1. Connection Oriented Service
2. Connectionless Services

Connection Oriented Services

There is a sequence of operation to be followed by the users of connection oriented service. These are :

1. Connection is established
2. Information is sent
3. Connection is released

In connection oriented service we have to establish a connection before starting the communication. When connection is established we send the message or the information and then we release the connection.

Connection oriented service is more reliable than connectionless service. We can send the message in connection oriented service if there is an error at the receivers end. Example of connection oriented is TCP (Transmission Control Protocol) protocol.

Connection Less Services

It is similar to the postal services, as it carries the full address where the message (letter) is to be carried. Each message is routed independently from source to destination. The order of message sent can be different from the order received.

In connectionless the data is transferred in one direction from source to destination without checking that destination is still there or not or if it prepared to accept the message. Authentication is not needed in this. Example of Connectionless service is UDP (User Datagram Protocol) protocol.

Difference between Connection oriented service and Connectionless service

1. In connection oriented service authentication is needed while connectionless service does not need any authentication.
2. Connection oriented protocol makes a connection and checks whether message is received or not and sends again if an error occurs connectionless service protocol does not guarantees a delivery.
3. Connection oriented service is more reliable than connectionless service.
4. Connection oriented service interface is stream based and connectionless is message based.

Wired and Wireless Netweork

Wired Networks

Wired networks, also called Ethernet networks, are the most common type of local area network (LAN) technology. A wired network is simply a collection of two or more computers, printers, and other devices linked by Ethernet cables. Ethernet is the fastest wired network protocol, with connection speeds of 10 megabits per second (Mbps) to 100 Mbps or higher. Wired networks can also be used as part of other wired and wireless networks. To connect a computer to a network with an Ethernet cable, the computer must have an Ethernet adapter (sometimes called a network interface card, or NIC). Ethernet adapters can be internal (installed in a computer) or external (housed in a separate case). Some computers include a built-in Ethernet adapter port, which eliminates the need for a separate adapter.

Wireless Networks

A wireless network, which uses high-frequency radio waves rather than wires to communicate between nodes, is another option for home or business networking. Individuals and organizations can use this option to expand their existing wired network or to go completely wireless. Wireless allows for devices to be shared without networking cable which increases mobility but decreases range. There are two main types of wireless networking; peer to peer or ad-hoc and infrastructure. 

An ad-hoc or peer-to-peer wireless network consists of a number of computers each equipped with a wireless networking interface card. Each computer can communicate directly with all of the other wireless enabled computers. They can share files and printers this way, but may not be able to access wired LAN resources, unless one of the computers acts as a bridge to the wired LAN using special software.

  

An infrastructure wireless network consists of an access point or a base station. In this type of network the access point acts like a hub, providing connectivity for the wireless computers. It can connect or bridge the wireless LAN to a wired LAN, allowing wireless computer access to LAN resources, such as file servers or existing Internet Connectivity.

Wired Networks
Pros	Cons
Ethernet cables, hubs and switches are very inexpensive. Some connection sharing software packages, like ICS, are free. Ethernet cables, hubs and switches are extremely reliable. Wired LANs offer superior performance. Broadband routers offer equivalent firewall capability built into the device, configurable through its own software. Wired connections can reach networking speeds of up to 1000 Mbps with Gigabit Ethernet networking equipment, necessary for bandwidth hungry.	Need to run cables in difficult environments through walls, floors and ceilings. Cables need to be run from computer to computer and switch to switch. Process can be time consuming. Loose cables likely remain the single most common and annoying source of failure in a wired network.

Wireless Networks
Pros	Cons
The greater mobility of wireless LANs helps offset the performance disadvantage. Mobile computers do not need to be tied to an Ethernet cable and can roam freely within the WLAN range. It is relatively easy to set up a WAP and configure a WNIC using a wireless connection utility. Wireless networks have much less cabling which leads to a much neater working environment. You do not need to run cables across your house/office, which can create trip hazards across rooms, hallways and stairs. Also choosing to set-up a wireless network means that you do not need to run cables underneath carpets or drill holes through walls or ceilings to pass cables through.	Spread in limited area.  Effected by Weather.

Introduction

Networks:

A network is a group of two or more computer systems linked together. There are many types of computer networks, A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.

Some of the different networks based on size are:

• Local area network, or LAN
• Metropolitan area network, or MAN
• Wide area network, or WAN

Let's look at each of these in a bit more detail.

Local Area Network

A local area network, or LAN, consists of a computer network at a single site, typically an individual office building. A LAN is very useful for sharing resources, such as data storage and printers. LANs can be built with relatively inexpensive hardware, such as hubs, network adapters and Ethernet cables.

The smallest LAN may only use two computers, while larger LANs can accommodate thousands of computers. A LAN typically relies mostly on wired connections for increased speed and security, but wireless connections can also be part of a LAN. High speed and relatively low cost are the defining characteristics of LANs.

LANs are typically used for single sites where people need to share resources among themselves but not with the rest of the outside world. Think of an office building where everybody should be able to access files on a central server or be able to print a document to one or more central printers. Those tasks should be easy for everybody working in the same office, but you would not want somebody just walking outside to be able to send a document to the printer from their cell phone! If a local area network, or LAN, is entirely wireless, it is referred to as a wireless local area network, or WLAN.

Metropolitan Area Network

A metropolitan area network, or MAN, consists of a computer network across an entire city, college campus or small region. A MAN is larger than a LAN, which is typically limited to a single building or site. Depending on the configuration, this type of network can cover an area from several miles to tens of miles. A MAN is often used to connect several LANs together to form a bigger network. When this type of network is specifically designed for a college campus, it is sometimes referred to as a campus area network, or CAN.

Wide Area Network

A wide area network, or WAN, occupies a very large area, such as an entire country or the entire world. A WAN can contain multiple smaller networks, such as LANs or MANs. The Internet is the best-known example of a public WAN.

The ability to exchange data and communicate efficiently is the main purpose of networking computers. But we have to consider beyond these points to evaluate the feasibility of networking for our own advantages. A computer network can be identified as a group of computers that are interconnected for sharing data between them or their users. There is a wide variety of networks and their advantages and disadvantages mainly depend on the type of network.

Assignment#1

Assignment # 1

1Q: Write a note on wired(Guided) and wireless(Unguided) media and its types with its standards, connector's and application.


Issue Date : 27/01/2016
Submit Date: 08/02/2016

Please follow the proper format which have discussed in the class.

Syllabus

Syllabus

Unit-I Introduction

Introduction, Network Typologies, Wired Vs wireless Networks, LAN, MAN, WAN, Internet, Intranet & Extranet, Connection-Oriented and Connectionless Services, Need of Protocols, TCP/IP reference Model, comparison of OSI & TCP/IP. Bridges, Hubs and Switches, Virtual LANs.

Unit-II Network Protocols

ALOHA, Carrier Sense Multiple Access Protocols, ARP, RARP, Framing, One-Bit Sliding Window Protocol, Protocol Using Go Back N, Protocol Using Selective Repeat, High-Level Data Link Control (HDLC)

Unit-III Congestion Control in Data Networks

Congestion Prevention Policies, Congestion Control in Virtual-Circuit Subnets, Congestion Control in Datagram Subnets, Effects of Congestion, Load Shedding, Jitter Control, Congestion Control in Packet-Switching Networks

Unit-IV Routing Algorithms

The Optimality Principle, Shortest Path Routing, Flooding, Distance Vector Routing, Link State Routing, Hierarchical Routing, Broadcast Routing, Multicast Routing, Routing for Mobile Hosts, Routing in Ad Hoc Networks, Node Lookup in Peer-to-Peer Networks

Unit-V Internetwork Protocols

Internet Protocol & IP Addresses, Principles of Internetworking, Internet Protocol Operation, IPv6, Virtual Private Networks and IP Security