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Network Addressing
Networking for Home and Small Businesses – Chapter 5
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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
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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
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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
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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
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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??
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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
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Types of IP Addresses
 Class B
– Range 128-191
– N.N.H.H
– First bit in octet will be a 1
– Default subnet mask
• 255.255.0.0
– can create over 65,000 host addresses
• 216 – 2 = 65,534 to be exact
– Used in medium-sized organizations
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Types of IP Addresses
 Class C
– Range 192 -223
– N.N.N.H
– First two bits in octet will be a 11
– Default subnet mask
• 255.255.255.0
– can create 254 hosts
• 28 – 2 = 254 to be exact
– Used in small organizations
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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
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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
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Unicast Address
 Most common type of address
 Intended for a specific host
 Must have both destination IP and MAC in the header
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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
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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
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Using Static IP Addressing
 Manually configured by the network administrator
 Advantages
– useful for printers, servers, etc
– increased control of resources (security)
 Disadvantages
– time consuming
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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
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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
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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)
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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
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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
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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
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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
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