Unit-1
Linux Operating System
1.1 Networking concept:
- A network can be defined as a group of computers and other devices connected in some ways so as to be able to exchange data.
- Each of the devices on the network can be thought of as a node; each node has a unique address.
- Addresses are numeric quantities that are easy for computers to work with, but not for humans to remember. Example: 204.160.241.98
- Some networks also provide names that humans can more easily remember than numbers. Example: www.javasoft.com, corresponding to the above numeric address.
1.2 Data Communication Model:
Communication is a process of transferring messages from one point to another point .These are the basic element of communication system.
A Communication system has following components:
1. Message: It is the information or data to be communicated. It can consist of text, numbers, pictures, sound or video or any combination of these.
2. Sender: It is the device/computer that generates and sends that message.
3. Receiver: It is the device or computer that receives the message. The location of receiver computer is generally different from the sender computer. The distance between sender and receiver depends upon the types of network used in between.
4. Medium: It is the channel or physical path through which the message is carried from sender to the receiver. The medium can be wired like twisted pair wire, coaxial cable, fiber-optic cable or wireless like laser, radio waves, and microwaves.
5. Protocol: It is a set of rules that govern the communication between the devices. Both sender and receiver follow same protocols to communicate with each other.
1.3 Component of computer network:
A network is a group of two or more computers that are connected to share resources and information
A network is a group of two or more computers that are connected to share resources and information
- 1. Hosts-: A host is a computer that is accessible over a network. It can be a client, server, or any other type of computer. Each host has a unique identifier called a hostname that allows other computers to access it.
- 2. NIC-: A network interface card (NIC) is a circuit board or card that is installed in a computer so that it can be connected to a network.
- 3. Ethernet cable:- An Ethernet cable is a popular type of network cable used for high-speed connections between two devices such as computers and routers on IP networks. This type of cable is used to connect: a. computer to hub b. computer to switch c. router to hub d. router to switch
- 4. Hub , Switch or Router: Hubs are devices commonly used to connect segments of a LAN. switch is a central communication device for local area Ethernet networks. Many home broadband routers feature an embedded Ethernet switch. Routers are small electronic devices that join multiple computer networks together via either wired or wireless connections
- 5. Internet connection:-To connect to the internet , a network need an internet connection like dial-up connection, Broadband, ISDN etc.
1.4 Internet protocols:
- I.P stands for internet protocol.
- .An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.
- Every machine has a unique I.P address.
- The Internet Protocol (IP) is the method or protocol by which data is sent from one computer to another on the Internet.
- Types of IP addresses: Static IP addresses: Dynamic IP addresses The two versions of IP addresses currently running are IP versions 4 (IPv4) and IP versions 6 (IPv6).
1.5 Classes of IP Address:
The classes of IPv4 addresses
The different classes of the IPv4 address are the following:
- Class A address
- Class B address
- Class C address
- Class D address
- Class E address
Class A Address
- The first bit of the first octet is always set to zero. So that the first octet ranges from 1 – 127. The class A address only include IP starting from 1.x.x.x to 126.x.x.x. The IP range 127.x.x.x is reserved for loop back IP addresses. The default subnet mask for class A IP address is 255.0.0.0. This means it can have 126 networks (27-2) and 16777214 hosts (224-2). Class A IP address format is thus: 0NNNNNNN.HHHHHHHH.HHHHHHHH.HHHHHHHH.
Class B Address
- Here the first two bits in the first two bits is set to zero. Class B IP Addresses range from 128.0.x.x to 191.255.x.x. The default subnet mask for Class B is 255.255.x.x. Class B has 16384 (214) Network addresses and 65534 (216-2) Host addresses. Class B IP address format is: 10NNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH
Class C Address
- The first octet of this class has its first 3 bits set to 110. Class C IP addresses range from 192.0.0.x to 223.255.255.x. The default subnet mask for Class C is 255.255.255.x. Class C gives 2097152 (221) Network addresses and 254 (28-2) Host addresses. Class C IP address format is: 110NNNNN.NNNNNNNN.NNNNNNNN.HHHHHHHH
Class D Address
- The first four bits of the first octet in class D IP address are set to 1110. Class D has IP address rage from 224.0.0.0 to 239.255.255.255. Class D is reserved for Multicasting. In multicasting data is not intended for a particular host, but multiple ones. That is why there is no need to extract host address from the class D IP addresses. The Class D does not have any subnet mask.
Class E Address
- The class E IP addresses are reserved for experimental purpose only for R&D or study. IP addresses in the class E ranges from 240.0.0.0 to 255.255.255.254. This class too is not equipped with any subnet mask.
1.6 TCP/IP:
- TCP stands for Transmission Control Protocols.
- TCP is a connection-oriented Protocols.
- TCP rearrange data packet in order specified.
- TCP is a collection of protocols that govern the way data travel from one machine to another computer.
- TCP enables two hosts to establish a connection and exchange streams of data.
1.7 IP Routing:
1.
IP Routing is
a set of protocols that determine the path that data follows to travel across
multiple networks from its source to its destination.
2. When
data is transferred from one device to another on an IP network, like the
Internet, the data is broken down into smaller units called packets.
There are two primary
forms of IP routing-
Static
Routing
1. It
is the manual configuration and selection of a network route, usually managed
by the network administrator.
2. The
administrator constructs the routing table in every router by putting in the
entries for every network that could be a destination.
3. Static
routes to network destinations are unchangeable.
4. The
topology is given below;
Dynamic
Routing
1. Routing
protocols are used to facilitate the exchange of routing information between
routers.
2. A
routing protocol is a set of processes, algorithms, and messages that are used
to exchange routing information and populate the routing table with the routing
protocol’s choice of best paths.
3. The
purpose of dynamic routing protocols includes:
a. Discovery
of remote networks
b. Maintaining
up-to-date routing information
c.
Choosing the best path to destination
networks
d.Ability to find a new
best path if the current path is no longer available.
1.8
Dynamic Host Configuration Protocols
- DHCP (Dynamic Host Configuration Protocol) is a network management protocol used to dynamically assign an Internet Protocol (IP) address to any device, or node, on a network so they can communicate using IP.
- DHCP can be implemented on small local networks as well as large enterprise networks.
- DHCP-enabled clients send a request to the DHCP server whenever they connect to a network.
- DHCP is a client-server protocol in which servers manage a pool of unique IP addresses, as well as information about client configuration parameters, and assign addresses out of those address pools
- A DHCP server manages a record of all the IP addresses it allocates to network nodes.
- DHCP is an extension of a 1985 network IP management protocol, Bootstrap Protocol (BOOTP).