1. Computer Communication and Networking
Abdul Wahab Yaqoob
B.E(Telecom)MUET,CCNA,CCNP,MCSA,CCDA
Department of Information Technology
Campus Dadu ,University of Sindh
Unit #01 Lecture#02
IPv4 Addressing

2. Computer Communication and Networking
Title of Subject : Computer Communication and Networking
Effective : 2K13 Batch
Marks : 100(theory) (Practical)
Credit Hours : 2+1
This Class will meet at: 9:00-11:00 AM on Thursday
Recommended Books 
” Data Communications & Networking”, by Behroz Forouzan
 ” Data and Computer Communications”, by William Stallings
 ” Computer Networks, 4th Edition”, by Andrew S Tanenbaum
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3. Computer Communication and Networking
IPv4 Addressing
Binary and decimal
Types of IP addresses
Assigning addresses
Network part and subnet masks
Calculating addresses
Ping and Traceroute Utilities
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4. Computer Communication and Networking
IP addressing – works at
OSI model layer 3
TCP/IP model Internet layer
Application
Presentation
Session
Transport
Network
Data link
Physical
Application
Transport
Internet
Network Access
TCP, UDP IP
Ethernet, WAN technologies
HTTP, FTP, TFTP, SMTP etc
Segment
Packet
Frame
Bits
Data stream
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5. Computer Communication and Networking
Binary and decimal
Convert to 8-bit binary
248
187 89
Convert to decimal
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6. Computer Communication and Networking
Binary and decimal
Convert to 8-bit binary
Convert to decimal
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7. Computer Communication and Networking
IPv4 Address Classes
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8. Computer Communication and Networking
IPv4 Address Classes
Class D Addresses
A Class D address begins with binary 1110 in the first octet.
First octet range 224 to 239.
Class D address can be used to represent a group of hosts called a host group, or multicast group.
Class E Addresses First octet of an IP address begins with 1111
Class E addresses are reserved for experimental purposes and should not be used for addressing hosts or multicast groups. 
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9. Computer Communication and Networking
Find the network address
192.
168.
21. 17
In a network address, all the host bits are 0.
192.
168.
21.
The router needs to do this for every packet.
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10. Computer Communication and Networking
Logical AND
192.
168.
21. 17
255.
192.
168.
21.
Do a logical AND at each position
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11. Computer Communication and Networking
Find the broadcast address
192.
168.
21. 17
In a broadcast address, all the host bits are 1.
192.
168.
21.
255
The broadcast is the last address in the network.
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12. Computer Communication and Networking
3 types of address
Every network has:
Network address – the first one
Broadcast address – the last one
Host addresses – everything in between
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13. Computer Communication and Networking
Calculating addresses
A host has IP address /24
What is the subnet mask?
What is the network address?
What is the broadcast address?
What is the range of host addresses in the network?
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14. Computer Communication and Networking
Calculating addresses
A host has IP address /26
What is the subnet mask?
What is the network address?
What is the broadcast address?
What is the range of host addresses in the network?
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15. Computer Communication and Networking
Unicast, Multicast, Broadcast
Unicast – a message addressed to one host
Broadcast – a message addressed to all hosts on a network. Uses network’s broadcast address or locally
Multicast – a message addressed to a group of hosts. Uses an address starting
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16. Computer Communication and Networking
Private IP addresses
Unrestricted use on private networks. Not routed across the Internet.
– ( /8)
– ( /20)
– ( /24)
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17. Computer Communication and Networking
Public IP addresses
Routed over the Internet
Master holder is IANA
Assigned to regional registries and then to ISPs
ISPs allocate them to organisations and individual users
Use is strictly controlled as duplicate addresses are not allowed
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18. Computer Communication and Networking
Special addresses
“all addresses” in default route. Hosts cannot be given addresses starting 0.
is loopback. Hosts cannot be given addresses starting 127.
and higher – reserved for experimental purposes.
local only
to for teaching
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19. Computer Communication and Networking
Network address translation NAT
A large number of hosts on a network use private addresses to communicate with each other.
The ISP allocates one or a few public addresses.
NAT allows the hosts to share the public addresses when they want to use the Internet
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20. Computer Communication and Networking
Addressing hosts
Static addressing – address is configured by an administrator
Servers, printers, routers, switches need static addresses
Dynamic addressing – address is allocated automatically by DHCP by leasing addresses from a pool
Dynamic addressing is best for workstations
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21. Computer Communication and Networking
Ping and traceroute
Ping sends an ICMP message. If all is well, the destination replies. If not, a router may reply to say the destination is unreachable, or the ping may time out.
Traceroute sends a series of messages so that each router along the path replies. You get a list of addresses of all the routers.
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22. Computer Communication and Networking
IP v4 Address Allocation
History
1981: IPv4 Protocol was published.
1985: 6% of IPv4 address space in use.
2001: 66% of IPv4 address space in use.
2010: 96% of IPv4 address space in use.
NEED OF IPv6
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23. Computer Communication and Networking
IPv6
Development started in 1990s because of concerns about IPv4 addresses running out
A whole new protocol suite – not just layer 3
Uses 128-bit hierarchical addressing, written using hexadecimal
Simpler header
Integrated security – authentication, privacy
Quality of service mechanisms
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24. Computer Communication and Networking
Larger Address Space
IPv4
32 bits or 4 bytes long
4,200,000,000 possible addressable nodes
IPv6
128 bits or 16 bytes: four times the bits of IPv4
3.4 * 1038 possible addressable nodes
340,282,366,920,938,463,374,607,432,768,211,456
5 * 1028 addresses per person
50,000,000,000,000,000,000,000,000,000
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25. Computer Communication and Networking
IPv6 Advantage
Larger address space (2^128 Address)
Elimination of NAT
Elimination of broadcast addresses
Simplified header for improved router efficiency
Support for mobility and security
Transition richness
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