Chapter 5

© 2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1

Network Addressing

Networking for Home and Small Businesses – Chapter 5

ITE PC v4.0Chapter 1 2© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Purpose of an IP Address A logical network address that identifies a host

A host (end-user) must have a NIC card– workstations

– servers

– printers

– router interface

Each packet will contain a source and destination IP address

Packet Tracer Activity 5.1.1 – Section 2


IP addresses

32 binary digits

4 octets

Dotted decimal notation

IP Version 4– most common form of IP addresses

Over 4 billion possible IP addresses


Binary Numbers The IP address is made up of binary numbers (1 or 0)

Humans must be able to talk computer language to send data

We do this by converting our numbering system (Base 10 to binary)

Let’s try some . . .Convert 140 to binary

Convert 10 to binary

Convert 11010111 to Base 10

Convert 11111110 to Base 10

Time to play a game -- Online Activity 5.1.2 – Section 3


Parts of an IP Address Hierarchial

– made up of 2 parts

• network

• host

– determined by IP class

Similar to your phone number– Area code = network

– phone number = host


Purpose of the Subnet Mask Helps identify network bits (all 1s) and host bits

Boolean math or “ANDING”

What happens if both source and destination IP are on the same network??


Types of IP Addresses Class A

– Range 1-127

– N.H.H.H

– First bit in octet will be a 0

– Default subnet mask

• 255.0.0.0

– can create over 16 million host addresses

• 224 – 2 = 16,777,214 to be exact

• why do you subtract 2???

– Used in large organizations


Types of IP Addresses Class B

– Range 128-191

– N.N.H.H

– First bit in octet will be a 1


• 255.255.0.0

– can create over 65,000 host addresses

• 216 – 2 = 65,534 to be exact

– Used in medium-sized organizations


Types of IP Addresses Class C

– Range 192 -223

– N.N.N.H

– First two bits in octet will be a 11


• 255.255.255.0

– can create 254 hosts

• 28 – 2 = 254 to be exact

– Used in small organizations


Types of IP Addresses Class D

– Range 224 - 239

– used for multicasting

– not for commercial use

Class E– Range 240 - 255

– reserved for experimental use

– not for commercial use


Private IP Addresses Helps avoid the problem of limited IP addresses

Allows hosts to communicate locally without each device needing a public IP address

Not routed on the Internet; blocked by the ISP router

Private address ranges assigned by RFC 1918

– Request for comment

– all classes can be used for any size network

– most use Class A


Unicast Address Most common type of address

Intended for a specific host

Must have both destination IP and MAC in the header


Broadcast Address All ones in the host portion of the IP address

– Class C address: 204.33.4.0 (N.N.N.H)

– Broadcast address: 204.33.4.255

MAC address all Fs – FF-FF-FF-FF-FF-FF


Multicast Address Send packet to a group of devices

Must use multicast address range

Range 224.0.0.0 – 239.255.255.255

Used for remote gaming

MAC address begins with:– 01-00-5E


Using Static IP Addressing Manually configured by the network administrator

Advantages– useful for printers, servers, etc

– increased control of resources (security)

Disadvantages– time consuming


Using Dynamic IP Addressing Automatic assignment of IP addresses

Useful if frequent change in users (wireless hotspot)

Uses DHCP (Dynamic Host Configuration Protocol) server

IP addresses leased for a period of time– if host is removed from the network (turned off), the IP address goes back into the pool of IP address

Preferred method for large networks– reduces the burden of network support


Configuring DHCP If host is configured as DHCP client, it will not have a

– IP address

– Subnet Mask

– Default Gateway

Clients send a DHCP address– Broadcast IP and MAC

• only DHCP server replies

Server responds with DHCP offer of an IP address

Host/client sends DHCP request asking server to use the IP address

Server responds with DHCP acknowledgment


Obtaining an IP address from DHCP server Multifunction device (Linksys Router) provides services

to clients (SOHO network)

Configuring the DHCP server– Enter router default IP address and subnet mask for internal interface

• IP = 192.168.1.1

• Subnet Mask = 255.255.255.0

–On DHCP screen

• check range

• number of users

• lease time (24 hours by default)


Purpose of a Gateway

Used by the router to provide the path through which hosts on one network can communicate with hosts on a different network

Default gateway address

– IP address of the router interface

If DHCP is being used

– the DHCP server will automatically send the correct IP interface to the host to use as the default gateway


Address Assignment

ISR (Integrated Services Router)

Default IP address– Class C Private Address

– Configured on router interface

Internal hosts must be assigned addresses within the same network


Address Management Direct Connection

– direct connection from PC to ISP through modem

– public address assigned to the host

Connection through Integrated Router– more than one host needs access to the Internet

– modem connected to ISR

Connection through Gateway Device– ISR and modem in one unit

– connect directly to ISP


Using NAT with a Home or Small Business Network NAT (Network Address Translation)

Translates private IP addresses into unique public address for Internet communication

Only packets destined for different network use NAT


Chapter 5

Technology

cisco systems

cisco public

ip address server

ip address hostclient

ip address hierarchial

ip address class c address

dhcp address broadcast

dynamic ip