Introduction

Select Certification Bootcamp :
MCSE MCSE+Security CCNA CCNP RHCE Register Course Fees Home

Leading MCSE, CCNA, CCNP Certification boot camp training provider in India, USA, UK.

Introduction

A TCP/IP address typically has two components: the network ID of the address, which specifies the general location of the host, and the host ID, which uniquely identifies an individual host after the network is located. In most cases, you will need to break your network into smaller more manageable pieces—notably you will segment your network for performance. If you are using TCP/IP these segments are referred to as subnets.

A subnet is really a subnetwork of a TCP/IP internetwork. An internet or internetwork is a group of computers linked together using TCP/IP technology. An internet can be either a portion of the Internet (the worldwide network of publicly interconnected TCP/IP networks) or a private corporate or enterprise internetwork. Such private internetworks are usually called intranets to show that they are internal to an enterprise and not part of the Internet.

The term network is used when it is not necessary to distinguish between individual subnets and internetworks. A subnet is simply a subdivision of a network. You create a subnet by carefully choosing the IP addresses and subnet masks for your hosts. This process is known as subnet addressing or subnetting. The term subnetworking or subnetting refers to the use of a custom subnet mask to subdivide a single network ID into multiple network IDs.

An IP address consists of four octets, which are numbers between 0 and 255. These are strung together with periods to look like this example 200.20.5.59. This number is a representation of a 32 binary number—made easier for humans to understand. Part of the address identifies the host’s network or subnet, and part of the address identifies the host. The subnet mask specifies what portion of the TCP/IP address identifies which part. A subnet mask can also specify how much of the address will instead specify a subnet ID.

The subnet mask is used by the Internet layer (IP layer) to route a TCP/IP packet to its proper destination. When a TCP/IP address is combined with a subnet mask, the TCP/IP protocol determines whether the destination is on the local subnet or not. If the destination address is on a different subnet than the sender is, then it is determined to be on a remote network and the packet is routed appropriately—normally through the default gateway. If the destination address is on the local subnet, the packet is not routed but sent directly to the destination host.

If a network has a small number of hosts that are all on the same segment that is no connection to any other network, they are all given the same network ID. Subnets are not needed in this case. If the network is larger, however, with remote segments connected by routers (an internetwork), then each individual subnet needs a different network ID. It is possible to assign a different network ID to each network segment, but organizations are usually given only one network ID for the entire organization. A subnet mask must then be used to use part of the host ID as the subnet ID. When assigning IP addresses and subnet masks, you must know how many subnets are required and the maximum number of hosts that are on each subnet. Then you can use a subnet mask that allows enough hosts on each subnet while allowing for enough subnets within the entire network.

Depending on the subnet mask selected, the internetwork can either have a lot of subnets with fewer hosts on each subnet, or a smaller number of subnets with a larger number of hosts on each subnet. The purpose of this chapter is to show how to determine the proper subnet mask to be used to meet the addressing requirements.

This chapter discusses the following topics:

Subnet masks, host IDs, and network IDs
The limitations of using a default subnet mask
Subnetting—how to increase the number of subnets on the network by using a custom subnet mask
Three different procedures for subnetting an internetwork
Shortcuts to reduce the time it takes on the exam to subnet a network ID

Vibrant Advantage :

No Prestudy
Longest Duration Camp
Chalk Talk Training
Highest Passing Rate
Bootcamp since 1999
Guaranteed Certification ...

Testimonials :

MCSE Certification boot camp

The instructor taught real world experience and did not just teach us to pass the test. He knew the subject well and was encouraging. His lectures were very well delivered....

Colver Dennis, USA