Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Unit-II CHAP-II

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Tcp/ip networking TCP/IP are used to connect diff. Networks and provides basic networking functionality. There are other protocols also which are used in communication of networks. They are ARP, address resolution protocool, DNS, Domain name system, ICMP, internet control message protocol, UDP, User datagram protocol, RIP, Routing Information protocol, SMTP, Simple mail transfer protocol, Telnet and many others.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Tcp/ip networking Each device that transmits information on network is idetified by a unique address. This address has a standard format consisting of two parts. The network layer address: it is a address of the network to which device is connecte. Media access control (MAC) address: it is a address of the device it self, it may be a node or host address.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Tcp/ip networking The network layer address is a IP address that has been assigned to the device. The Mac address is built into the card by the manufacturer and is used to transfer data between devices. When data is transferred between computers the long stream of data is divided into small packets. To improve communication performance between two network devices, it is beneficial to subdivide the message into packets.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Tcp/ip networking Each packet is then sent individually through a computer network. Packet format generally contains a header ie. the destination address, body contains the messag data and some times a footer contains data signifying the end of packets. The receiving device reassembles the packets in the correct sequence and retrieves the original message.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Network classes IP addresses may be permanent or temporarily. It serves two purposes: location addressing and computer host or network identification. Two versions of IP are IPV6 & IPV4 are used. IPV6 makes the uses of 128 bits for the IP address and its development is still in process. IPV4 makes the uses of 4 bytes, denoted by 4 decimal numbers and are written in standard dot notation. For eg. 192.169.125.112. this decimal nos. must be in the range of 0 to 255.

Network classes IP addresses are divided into five classes: Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Network classes IP addresses are divided into five classes: Class A addresses were used for large networks. Class B was designed for use on medium to large networks. Class C for small LANs Class D and E were used for multicast and experimental purposes.

Reserved networks Numbers Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Network classes Reserved networks Numbers Network Class Net Mask Network Address A 255.0,0,0 10.0.0.0-10.255.255.255 B 255.255.0.0 172.16.0.0 – 172.31.255.255 C 255.255.255.0 192.168.0.0-192.168.255.255

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W NETWORK CLASSES In short, the following determines, by default in three classes of network, which are part of the IP address belongs to the network (N) and which part belongs to the host (H) Class A : nnnnnnnn.hhhhhhhh.hhhhhhhh.hhhhhhhh Class B : nnnnnnnn.nnnnnnnn.hhhhhhhh.hhhhhhhh Class C : nnnnnnnn.nnnnnnnn.nnnnnnnn.hhhhhhhh

Network classes IP numbers can be interpreted in three ways: Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Network classes IP numbers can be interpreted in three ways: Address of a network: it represents all the devices that are physically connected to each other. Broadcast address: it is the address that enables all devices on the network to be contacted. Actual interface address: while setting up Ethernet device, eth0, we have to pass some information in ifcg-eth0 file. Subnet mask is one of the parameter in that file, which is referred as network mask or subnet mask. It is not an IP number, it just modify the way IP numbers are interpreted on the same network segment. Network mask is the determining factor in subnetting. In setting up NIC, we use a net mask of 255.255.255.0. In this case, all the network bits are set to one and host bits are set to zero.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Network classes After configuring network card (NIC) by above command on each computer on network, modify the following files present in /etc directory. /etc/nsswitch.conf /etc/host /etc/resolv.conf /etc/sysconfig/network From above the file /etc/nsswitch.conf file contains all information for the name resolver. This file should contain following line. Hosts: files dns. File /etc/hosts contains all the computers on the network (local network or outside network). File /etc/resolv.conf file provides information regarding name servers used to resolve hostnames.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Network classes Following command is used to configure ethernet (internal network) interface: Ifconfig eth0 <> netmask <> broadcast<> In above command <> is replaced with corresponding values. For this a file, ifcfg-eth0 is created in /etc/sysconfig/network-scripts. This file shows some information along with the details which have been provided in above command.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Network classes File /etc/resolv.conf file contains a listing of the domain on the network. File /etc/sysconfig/network file contains the following lines. NETWORKING : YES It enables networking for our system. HOSTNAME: host and domain name of system. It shows the hostname along with the domain name of your system.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Subnetting Subnetting means a logical practice of dividing a network into two or more networks. Ip numbers are assigned to network interfaces on hosts. Many computers can have a single network interface and a single IP number. It is also possible that a single computer can have more than one IP address to a single NIC. Consider the following lines: ifconfig eht0:1 192.1.68.1.4 route add –host 192.168.1.4 dev eth0 The first command provides the IP address to the virtual interface eth0:1 and 2nd command adds a route for the address to the actual device eth0.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W SUBNETTING Consider the following table which shows binary to decimal conversion. Consider following binary & decimal notation. (11000000.10101000.00000001.00000001)2 ( (128+64) . (128+32+8) . (1) . (1) ) 10 Ie actual ip is : (192.168.1.1) 1 128 64 32 16 8 4 2

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W subnetting In class C network is divided into two subnetworks. 1st is given by mask 255.255.255.128 as the net mask. Following table shows the two subnets of Class C network. Network Net mask Broadcast First IP Last IP 192.168.1.0 255.255.255.128 192.168.1.127 192.168.1.1. 192.168.1.126 192.168.1.128 192.168.1.255 192.168.1.129 192.168.1.254

Subnetting Class C Subnets and subnet masks are as follows: Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Subnetting Class C Subnets and subnet masks are as follows: Number of bits (n) Number of Subnets (2n ) Subnet mask (M) Number of hosts (254-M) 1 2 255.255.255.128( 128=27) 126 4 255.255.255.192 (128+64) 62 3 8 255.255.255.224(192+32) 30 16 255.255.255.240(224+16) 14 5 32 255.255.255.248(240+8) 6 64 255.255.255.252(248+4)

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W cider Classless Inter Domain Rotuing (CIDR) was introduced to enhance space utilization and routing scalability in the internet. The main advantage behind it was to kep the internet running out of IP. The allcation of IP through classful system can be very inefficient. It was wasteful when anyone need for than 254 host address was given a Class B address block 65533 host addresses. Even more wasteful were companies and organizations that were allocated Class A address blocks, which contain over 16 million host address. This cause a huge wastage as in actual only a little percentage of allocated Class A and Class B space has ever been assigned to a host computer on the internet.

Created by : Asst. Prof. Ashish Shah, J. M Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W cider Later after eliminating class system, address could be conserved. For this purpose a scheme known as supernetting was proposed in 1992. According to this scheme accurate number of address space is allocated that was actually needed. It avoid the crisis of shortage of address space for many years. Under this, the classful subnet masks are extended so that a network address and subnet mask could subnets with one address. For eg, if you need 1000 addresses, you supernet four class C networks together as shown in below(p.t.o.)

Supernet – subnetting Suprnet of subnetting of Class C 192.168.128.0 Created by : Asst. Prof. Ashish Shah, J.M. Patel College of Commerce, Goregoan W Supernet – subnetting Suprnet of subnetting of Class C 192.168.128.0 192.168.129.0 192.168.130.0 192.168.131.0