TCP/IP Overview

The TCP/IP is a network protocol which provides communication across computers with diverse H/w architectures and various OS. It provides high-speed communication links using packet-switching networks to government agencies, universities and corporations. Microsoft TCP/IP is a routable enterprise network protocol. Mostly OS use TCP/IP protocol for communicating.

IP-address

An IP address is a unique, numeric identifier used to specify a particular host computer on a network, and it is part of global, standardized scheme for identifying machines that are connected to the internet. Each computer running TCP/IP requires IP address. IP addresses consist of four numbers between 0 to 255, separated by periods, which represent both the network and the host machine. It is 32 bits long.
If we change IP address, then after changing the IP address the network is not enabled. Then in case of Win 98 restart the system and in case Win 2k/XP, once disable the LAN and then enable again.
There are five classes of IP address.
• Class –A : - In this class first 8 bits are used for network address and the last 24 bits are used for host address. The range of first 8 bits is from 1 to 126 . The first part of the IP address is not representing by 0 and the 127 is used for loop back function. The other numbers can be between 0 to 255.
• Class –B : - In this class first 16 bits are used for network address and the last 16 bits are used for host address. The range of first 8 bits is from 128 to 191 . The other numbers can be between 0 to 255.
• Class –C : - In this class first 24 bits are used for network address and the last 8 bits are used for host address. The range of first 8 bits is from 192 to 223 . The other numbers can be between 0 to 255.
• Class –D : - This class is used for multicasting means video conferencing. The range of first 8 bits is from 224 to 239 .
• Class –E : - This class is under R & D (Research & Development).

Subnet mask
It is a network in a multiple network environment that uses IP address derived from a single network ID. Using subnet mask an organization can divide a single large network into multiple physical networks and connected them with routers. A router is a device that is used to connect networks of different types, such as those using different architectures and protocols.
A subnet mask is used to block out a partition of the IP address so that TCP/IP can distinguish the network ID from the host ID. When TCP/IP host try to communicate, the subnet mask is used to determine whether the destination host is located on a local or a remote network. Subnet mask is 32 bits.
Class – A 255.0.0.0
Class – B 255.255.0.0
Class – C 255.255.255.0
Normally Class – C subnet mask is used.

Default Gateway
For communication with a host on another network, we use gateway. Default gateway is address of router. In a network without router or in a local network, we set it blank.
We can configure TCP/IP properties manually or automatic .

To manually configure TCP/IP
1. Select properties of ‘My network places'.
2. Select properties of LAN connection.
• Select TCP/IP protocol, and then click on Properties .
• In the IP address tab, enter the IP address , subnet mask and default gateway .
To configure the TCP/IP automatically we need to install DHCP server.

2 NIC (2 LAN card)
Two LAN cards are used to connect two different class networks. One LAN card has the IP address of one network and the second has the IP address of second network. The computer, which connect two networks or which have 2 LAN card is work like a router , called MULTIHOME .


We can use a single LAN card as 2 or more LAN cards by giving it more IP address. Steps to add more IP address to a single LAN card:
1. Select the LAN connection from the properties of ‘My network places'.
2. Select the TCP/IP protocol from the properties of ‘LAN connection'.
3. Open the properties of TCP/IP protocol.
4. LAN card has an IP address of one network, click on Add to add more IP address and then enter the IP address of other network.
5. Then OK. Now when we run IPCONFIG, it show us more IP address of a single LAN card.