Computer Network Architecture
Lecture10: IP Addressing II
26/1/2013
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Addressing Types of Communication
• There are three
communication:
types
of
Addressing
in
• Unicast communication
• Broadcast communication
• Multicast communication
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Addressing Types of Communication(Con.)
• In an IPv4 network, the hosts can communicate in one of three
different ways:
• Unicast communication: The process of sending a packet
from one host to an individual host.
•
Broadcast communication: The process of sending a packet
from one host to all hosts in the network.
• Multicast communication: The process of sending a packet
from one host to a selected group of hosts.
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Unicast Communication and Addresses
• The most common type of communication is unicast.
• This is the normal host-to-host communication in
both a client/server and a peer-to-peer network.
• For unicast communication, the host addresses
assigned to the two end devices are used as the source
and destination IPv4 addresses.
• During the encapsulation process, the source host
places its IPv4 address in the unicast packet header as
the source host address and the IPv4 address of the
destination host in the packet header as the
destination address.
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Unicast Communication and Addresses
• Figure 1 shows an example of IPv4 unicast communication
from computer A with the address 172.16.4.1 to the printer
with the address 172.16.4.253.
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Broadcast Communication and Addresses
• broadcast communication is the process of sending
a packet from one host to all hosts in the network.
• broadcast communication use special addresses as the
destination address. This special address, called the
broadcast address, allows all the receiving hosts to
accept the packet.
• There are two types of broadcasts: directed
broadcast and limited broadcast. Each of these two
types of broadcasts uses a different method of IPv4
addressing.
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Directed Broadcast
• A directed broadcast is sent to all hosts on a specific
network. This type of broadcast is useful for sending a
broadcast to all hosts on a nonlocal network.
• The used address in directed broadcast is with 1 value in
all the host bits.
• For example, for a host outside the network to
communicate with the hosts within the 172.16.4.0
network, the broadcast address of the packet would be
172.16.4.255.
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Limited Broadcast
• The limited broadcast is used for communication
that is limited to the hosts on the local network.
These packets use a destination IPv4 address of all 1s
(255.255.255.255).
• As an example, a host within the 172.16.4.0
network would broadcast to all the hosts in its
network using a packet with a destination address of
255.255.255.255.
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Limited Broadcast
• Figure 2 represents a limited broadcast from host A
with the address 172.16.4.1.
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Multicast Communication and Addresses
• The multicast communication reduces traffic by
allowing a host to send a single packet to a selected
set of hosts.
• IPv4 has set aside a special block of addresses from
224.0.0.0 to 239.255.255.255 as addresses for
multicast groups.
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Multicast Communication and Addresses
• In the multicast communication shown in Figure 6-8, the source host A,
with the address 172.16.4.1, creates a single packet addressed to the
multicast address 224.10.10.5.
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Types of Addresses in an IPv4 Network
• Within each IPv4 network, there are three types of
addresses:
■ Network address: A special address that refers to the
network
■ Broadcast address: A special address used to send
data to all hosts in the network
■ Host addresses: The unicast addresses assigned to
the end devices in the network
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Network Address
• The network address is a standard way to refer to a network.
For example, you could refer to the network inside the circle
in Figure 3 as “the 10.0.0.0 network.
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Broadcast Address
• The IPv4 broadcast address within a network is the
directed broadcast address.
• Unlike the network address, this address is used in
communication to all the hosts in a network.
• This special address for each network allows a single
packet to communicate to all the hosts in that
network.
• For example in Figure 3 in the preceding section, to
communicate with all the hosts in this network, use a
destination address 10.0.0.255, which is the broadcast
address for the network.
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Host Address
• Host Addresses As described previously, every end
device requires a unique unicast address to deliver a
packet to that host.
• In IPv4 addresses, you can assign the values between
the network address and the broadcast address to
the devices in that network.
• In Figure 3, the addresses between the network
address of 10.0.0.0 and the broadcast address of
10.0.0.255 are the host addresses. This means that
the addresses 10.0.0.1 to 10.0.0.254 can be assigned
to the host address.
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Thank You
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