The network layer is responsible for packet forwarding including routing through intermediate routers. It controls the operation of the subnet and decides which physical path data takes. Routing is the process of moving packets from source to destination, usually performed by routers. Internetworking connects different network technologies like LANs and WANs using devices like routers. The network layer uses IP addressing to identify devices and enable routing. Private IP addresses identify internal devices while public addresses provide external internet access.

1. TOPIC : NETWORK
LAYER
PRESANTED BY:
M ADEEL RAJPUT
Student of BS (IT) at Shaheed Benazir Bhutto University
madeelrajput13@gmail.com

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NETWORK LAYER

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OSI REFERENCE MODEL
3. Network Layer
The network layer is layer 3. The network layer is
responsible for packet forwarding including routing
through intermediate routers
Controls the operation of the subnet.
Decided which physical path the data take.
 Subnetting is a process of dividing large network
into the smaller networks based on layer 3 IP
address.
Routing packets from source to destination.
physical-Logical addressing.

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Routing
The process of moving a packet of data from
source to destination.
Routing is usually performed by a dedicated
device called a router. Routing is a key feature of
the Internet.

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Internetwork
 Internetworking is the process or technique of connecting different
networks by using intermediary devices such as routers or gateway
devices.
 Some different kinds of network technologies that can be interconnected
by routers and other networking devices to create an internetwork:

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IP ADDRESSING
IP address is a number (example shown right) used to indicate the
location of a computer or other device on a network using TCP/IP.
These addresses are similar to those of your house; they allow
data to reach the appropriate destination on a network and the
Internet.
IP Address divided into four(4) part

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Classes of IP ADDRESSING

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Network and Host Parts

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Public and Private IP Address
public IP address?
A public IP address is the address that is assigned to a
computing device to allow direct access over the Internet.
A web server, email server and any server device directly
accessible from the Internet are candidate for a public IP
address.
A public IP address is globally unique, and can only be
assigned to an unique device.

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Public and Private IP Address
PRIVATE IP ADDRESS
A private IP address is the address space allocated by NIC to allow
organizations to create their own private network.
Class Starting IP
Address
Ending IP
Address
# of Hosts
A 10.0.0.0 10.255.255.255 16,777,216
B 172.16.0.0 172.31.255.255 1,048,576
C 192.168.0.0 192.168.255.255 65,536

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IPv4 was the first version of Internet Protocol to
be widely used, and accounts for most of today’s
Internet traffic. There are just over 4 billion IPv4
addresses.
IPv4?
IPv6 is a newer numbering system that provides a
much larger address pool than IPv4, amongst
other features. It was deployed in 1999
IPv6?

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Internet Protocol
version 4 (IPv4)
Internet Protocol
version 6 (IPv6)
Deployed 1981 1999
Address Size 32 bit 128 bit
Address Format
Dotted Decimal
Notation: 192.149.252.76
Hexadecimal Notation:
3FFE:F200:0234:AB00:
0123:4567:8901:ABCD

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The Routing Information Protocol (RIP) is one of the
oldest distance-vector routing protocols which employ
the hop count as a routing metric.
RIP prevents routing loops by implementing a limit on the
number of hops allowed in a path from source to
destination.
Routing Information Protocol (RIP)

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Internet Control Message Protocol (ICMP)
The Internet Control Message Protocol (ICMP) is one of
the main protocols of the internet protocol suite.
for example, that a requested service is not available or
that a host or router could not be reached.

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The network layer is layer 3. The network layer is responsible for packet
forwarding including routing through intermediate routers
Conclusion
Network Layer
some different kinds of network technologies that can be interconnected by
routers and other networking devices to create an internetwork:
Internetwork
Routing is the process of selecting best paths in a network.
Routing

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Conclusion
A private IP address is a non-Internet facing IP address on an
internal network.
Private IP address
A public IP address is an IP address that can be accessed
over the Internet.
Public IP address
Internet Protocol is a set of technical rules that defines how
computers communicate over a network.
Internet Protocol
Address Size 32 bit
Address Format
Dotted Decimal Notation:
192.149.252.76