Section 4.2: Network Protocols

The network hosts communicate with each other on a network using a common language called a protocol. A protocol is a set of rules that governs the communication between the two communicating hosts on a network. A number of networking protocols exist but it is important that two hosts that need to communicate with each other use a common protocol. The two important protocols are most commonly used are NetBEUI/NetBIOS and TCP/IP.

Section 4.2.1: NetBEUI/NetBIOS

NetBEUI (Net BIOS Enhanced User Interface) NetBIOS (Network Basic Input Output System) are Microsoft protocols that are ideal for a small network or a workgroup. NetBEUI is an extended version of NetBIOS. It was used in Microsoft's early networking products such as Windows for work groups and LAN manager

Section 4.2.2:TCP/IP

TCP/IP (Transmission Control Protocol/Internet Protocol) is a set of two basic protocols that are most commonly used as networking protocols today. TCP operates at a higher level and IP handles lower-level transmissions from one computer to another. TCP/IP communications are always point-to-point. It issues unique identifier to a host computer called IP address such as 192.168.12.123.This identifier is quite difficult for people to remember, therefore, alphanumeric values called host names are used in place of IP addresses. For example Marketing and Sales can be used as host names, which finally need to be translated into its IP address.

On a small network host files can be used for IP address translation. These host files are ASCII text files that are located in /etc directory of the computer. On large networks the Domain Name Services (DNS) are used to resolve fully qualified domain names (FQDN's) to their IP addresses. The example of an FQDN is www.inscription.com. On a small windows only network the LMHOSTS (LAN Manager Hosts) files are used to translate computer names to their IP addresses. On large windows only Networks Windows Internet Naming Service (WINS) is used to dynamically map Net BIOS names to IP addresses.

Section 4.2.3: Working with DHCP

Dynamic Host Configuration Protocol (DHCP) is used to resolve host names to IP addresses. It also issues IP configuration data to every host on a network and saves an administrator from the trouble to configure a unique IP address for each host. It configures additional configuration parameters on client servers so that they can connect to other network resources such as WINS and DNS server.

The DHCP Server contains an address range from which it can supply addresses to its clients and it automatically renews the IP addresses on the clients when a client requests for renewal.

Section 4.2.4: Working with Subnets

Subnetting divides a big network into smaller networks. A TCP/IP host is configured using a unique IP address, a default gateway address, and a subnet mask. In an IP address the Subnet ID clarifies the bits that identify the network and the bits that identify the host. The IP Address along with subnet ID can also be written as 192.168.113.19 /24, where /24 represents the number of 1s in the subnet mask. A default subnet mask allows all the host it contains to be a part of one site.

The lower the number after the slash in the subnet mask, the greater the number of host addresses available on the subnet. Therefore, subnetting logically subdivides the address space by increasing the number of ones in the network's subnet mask.

Class

Default Subnet Mask

Range

A

255.0.0.0

1-126

B

255.255.0.0

128-191

C

255.255.255.0

192-223

Three classes of IP addresses are available for the different types of networks 'Class A, Class B, Class C. The table given below shows that:

  • Class A network can accommodate maximum number of host address (16,777,214)
  • Class B can accommodate 65,534 host addresses
  • Class C can accommodate the minimum number of host addresses (254).

Decimal

Binary

Class A

255.0.0.0

11111111.00000000.00000000.00000000

Class B

255.255.0.0

11111111.11111111.00000000.00000000

Class C

255.255.255.0

11111111.11111111.11111111.00000000

The IP addresses ranges 10.0.0.0 /8, 172.16.0.0 /12, and 192.168.0.0 /16 are considered private IP address ranges. IP address range 169.254.0.0 /16 is considered APIPA range