Unit 24 Network Design and Administration IP Addressing (Pt.1)

Unit 24 Network Design and Administration

IP Addressing (Pt.1)

IP addressing: Objectives To examine data sharing on computer

networks To outline the different network

protocols used in today’s computer networks

To understand the nature of IP addressing, classes of IP address

To understand the importance of subnet masks and subnetting

How do Computers Share data?

How is information and data passed around networks? (LAN’s and WAN’s)

How does an e-mail reach its destination?

How do you access the Internet and download a web site?

How does your word document reach the printer?

The Beginning When was the Internet created? Why was it created? When was the World Wide Web created? Why was it created?

Vint Cerf and Robert Khan in 1972, were given the task of finding a networking protocol that would allow effective communication between the next generation of ARPANET computers

Intro to IP addressing Vinton (Vint) Cerf, along with a group of Stanford

University graduates, in December 1974, designed a networking protocol which included a 32 bit IP address, with eight bits for identification of a network, and 24 bits for identification of a computer, which provided support for up to 256 networks, each with up to 16,777,216 unique network addresses.

It was assumed that the network design would eventually be re-engineered for a production system, but the architecture proved remarkably robust. Cerf has said that once the network was developed and deployed, it just "continued to spread without stopping!"

Introduction – What is an IP Address?Introduction – What is an IP Address?

Every machine with access to the Internet has a unique identifying number, called an Internet Protocol (IP) Address. A typical IP address looks like this:

216.27.61.137 To make it easier for humans to remember, IP

addresses are normally expressed in decimal format as a "dotted decimal number” (and then as a name using DNS)

But computers communicate in binary form. Look at the same IP address in binary:

11011000.00011011.00111101.10001001

IP Addresses

11011000.00011011.00111101.10001001IP addresses are considered 32-bit numbers

The four numbers in an IP address are called octets, because they each have eight positions when viewed in binary form.

Each octet can contain any value between 0 and 255, but only certain values can be allocated as routable IP addresses (explained later)

IP Addresses

How do you convert a Binary number to a decimal number?

Take the binary number - 10001001

What is the smallest and largest numbers that can be represented by 8 bits?

Classes of IP Address The octets serve a purpose other than simply separating the numbers.

They are used to create classes of IP addresses (IP version 4) that can be assigned to a particular business, government or other organisation based on size and need.

The octets are split into two sections: Net and Host. The Network section always contains the first octet. It is used to identify the network that a computer belongs to. Host (sometimes referred to as Node) identifies the actual computer on the network. The Host section always contains the last octet

Class A IP Addresses

This class is for very large networks, such as a major international company might have.

IP addresses with a first octet from 1 to 126 are part of this class. E.g 110.125.1.2

The other three octets are used to identify each host. This means that there are 126 Class A networks each with

16,777,216 possible hosts Class A networks account for half of the total available IP

addresses.

Class A IP Addresses

16,777,214 possible hosts/computers on a network

Note: The Network ID for a class A network is the first octet followed by 3 zeros E.g. 10.0.0.0

Class B IP Addresses Used for medium-sized networks. A good example

is a large college campus. IP addresses with a first octet from 128 to 191 are

part of this class. E.g. 135.122.56.1 Class B addresses also include the second octet

as part of the Net identifier. The other two octets are used to identify each host.

This means that there are 16,384 Class B networks each with 65,536 possible hosts/computers

Class B networks make up a quarter of the total available IP addresses.

Class B IP Addresses

65,534 possible hosts /computers on this network

Note: The Network ID for a class B network is the first 2 octets followed by 2 zeros E.g. 172.16.0.0

Class C IP Addresses Class C addresses are commonly used for small to

mid-size businesses. IP addresses with a first octet from 192 to 223 are

part of this class. E.g. 192.168.1.1 Class C addresses also include the second and

third octets as part of the Net identifier. The last octet is used to identify each host. This

means that there are 2,097,152 Class C networks each with 254 possible hosts/computers

Class C networks make up an eighth of the total available IP addresses.

Class C IP Addresses

254 possible hosts / computers

Note: The Network ID for a class C network is the first 3 octets followed by 1 zero E.g. 192.168.1.0

Example – A simple LAN

192.168.1.1

192.168.1.2

192.168.1.3

192.168.1.4

A Class C IP addressing system using 4 computers

IP Address Determination

IP Address class

IP Address Network IDRange of values

of w

A w.x.y.z w.0.0.0 1-126

B w.x.y.z w.x.0.0 128-191

C w.x.y.z w.x.y.0 192-223

D w.x.y.z Not available 224-239

E w.x.y.z Not available 240-255

Private IP Addresses A network manager / administrator can allocate IP addresses

as they see fit – there are no real rules when routing data around private networks, although all administrators must still allocate addresses according to the classes of IP address and appropriate subnet masks.

There are 3 main IP addresses that are always used for private networks, and are never routed to the Internet.

10.0.0.0 (hosts from 10.0.0.1 to 10.255.255.254) 172.16.0.0 (hosts from 172.16.0.1 to 172.16.255.254 192.168.1.0 (hosts from 192.168.1.1 to 192.168.1.254) 169.254.0.0 (Automatic Private IP Addressing – APIPA)

IP addresses you cannot assign

Value Why not?

127 This is an internal IP address to test for connectivity and IP prevalence

255 Used as a Broadcast address

224-239 Used as a Multicast address

240-254 For future use

169.254.0.0 Internal Microsoft address used as an ‘emergency’ address

Subnetting and Subnet Masks

IP routing protocols can be extended still further by the use of subnet masks.

A subnet mask is used for 2 main purposes

1. To allow further expansion to an existing network, by allowing additional segments to be added to a LAN. This allows other physical devices to be added

2. To define the type of network (whether class A, B or C)

Subnet MasksLet’s assume we have an IP address of:

192.168.1.5This is a Class C address (192) therefore the network

ID is192.168.1.0

And the address of the specific machine is.5

The subnet mask for this address would be:255.255.255.0

Therefore the subnet mask identifies this IP address as a Class C IP address

Subnet Mask Examples

Class A

Class C

Class B

Subnet Mask Examples

What is the Subnet Mask?

189.168.1.1

189.168.1.2

189.168.1.3

189.168.1.4

A Class B IP addressing system using 4 computers

255.255.0.0

The College Network

Bury College has over 1600 computers, laptops, servers etc spanned across 4 sites, Woodbury, Millennium, Prospects and Peel.

Due to the number of hosts / computers, what class of IP address does the college need?

A Class B IP Address – with the facility for 65,384 hosts

What will the subnet mask be?255.255.0.0

Using Subnet Masks: Bury College

Woodbury Centre

IP Address172.16.2.1

Millennium Centre

IP Address172.16.4.1

Subnet Mask: 255.255.0.0

The College Network

IP addresses can be allocated in 2 waysStatically and Dynamically

Devices such as Printers are allocated a static IP address so that all computers on the network can find them all of the time, without the need for re-mapping

Most computers on the Internet and within large LAN’s allocate IP addresses dynamically

The College NetworkUsing DHCP (Dynamic Host Configuration

Protocol) each time someone logs onto a client computer, the server allocates that computer an IP address, but it may not be the same address each time.

The address allocated will fall into the range of the Class B address the college has:

E.g. 172.16.1.10-254

Example of IP and Subnet at Bury College

In Summary:

InterNIC, under the authority of the Internet Assigned Numbers Authority (IANA), allocates the network portions of IP addresses to Internet Service Providers (ISPs)

ISPs and LAN managers are responsible for assigning the host portion of the IP address to machines within their local networks. (maybe by using DHCP)

Next week

Completing IP addressing exercises Creating a logical model for your Unit

24 Task 2 Assignment Examining Classless Inter-domain

Routing (CIDR)

And finally… Complete all the remaining questions

from 12-15. Questions to be completed for

Homework if not completed. Next lesson – To construct a logical

topology for Task 2 Next Week – to examine CIDR classless

IP addressing