Network fundamentals
This blog post covers the essential concepts of network fundamentals, offering a comprehensive guide for beginners and a solid refresher for professionals. We explore the basics of networking, including key topics such as network topologies, protocols, devices, and the OSI model. Whether you're new to networking or looking to strengthen your foundational knowledge, this post provides clear explanations and valuable insights to help you understand the core principles of how networks operate.
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Routers: Routers are devices that connect
multiple computer networks together and route network traffic between them.
They operate at the network layer (Layer 3) of the OSI model and use routing
tables to determine the best path for data packets to reach their destination.
Routers also provide functions such as network address translation (NAT), which
allows multiple devices on a local network to share a single public IP address.
Switch
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Switches are devices that connect multiple
devices within a local area network (LAN) and forward data packets to their
intended destination based on the MAC address of the devices. Unlike hubs,
which broadcast data to all devices on a network, switches create dedicated
connections between devices, leading to more efficient and secure data
transmission within the LAN.
Firewall:
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A firewall is a network security device or
software that monitors and controls incoming and outgoing network traffic based
on predetermined security rules. Firewalls can be implemented at the network
level (e.g., hardware firewall) or the host level (e.g., software firewall) and
help protect networks from unauthorized access, malicious attacks, and other
security threats.
Wireless LAN Controller (WLC):
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A WLC is a network device that manages multiple
wireless access points (APs) in a wireless LAN (WLAN). It centralizes the
configuration, security, and management of APs, allowing administrators to
easily deploy and maintain wireless networks. WLCs provide features such as
roaming support, radio frequency (RF) management, and authentication for
wireless clients.
Access Points (APs):
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APs are devices that allow wireless devices to
connect to a wired network. They transmit and receive wireless signals,
providing access to the network for Wi-Fi-enabled devices such as laptops,
smartphones, and tablets. APs are typically connected to a wired network
infrastructure and can be standalone devices or managed by a WLC.
Endpoints
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Endpoints are the devices connected to a
network, such as computers, printers, smartphones, tablets, and IoT devices.
They initiate and consume network services and communicate with other devices
on the network. Endpoints can be both sources and destinations of data packets
in a network.
Server:
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A server is a computer or software application
that provides services or resources to other devices on a network. Servers can
fulfill various roles, including file storage, email hosting, web hosting,
database management, and application hosting. They typically have more
processing power, memory, and storage capacity than client devices and are
designed to handle multiple client requests simultaneously.
OSI model vs. TCP/IP model
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The OSI reference model describes the functions
of a telecommunication or networking system, while TCP/IP is a suite of
communication protocols used to interconnect network devices on the internet.
TCP/IP and OSI are the most broadly used networking models for communication.
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The main similarity is in their
construction, as both use layers, although the OSI model consists of seven
layers, while TCP/IP consists of just four layers.
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Another similarity is that the upper layer for
each model is the application layer, which performs the same tasks in each
model but may vary according to the information each receives.
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The functions performed in each model are also
similar because each uses a network and transport layer to operate. The OSI and
TCP/IP model are mostly used to transmit data packets, although they each use
different means and paths to reach their destinations.
Advantages of OSI Model
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The OSI model helps users and operators of
computer networks:
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Determine the required hardware and software to
build their network.
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Understand and communicate the process followed
by components communicating across a network.
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Perform troubleshooting, by identifying which
network layer is causing an issue and focusing efforts on that layer.
The OSI model helps network device manufacturers and
networking software vendors:
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Create devices and software that can communicate
with products from any other vendor, allowing open interoperability
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Define which parts of the network their products
should work with.
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Communicate to users at which network layers
their product operates – for example, only at the application layer, or across
the stack.
IP address
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IP address is a numerical identifier that uniquely
identifies the devices in a computer network. Two types of IP address are
widely used in IP network.
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IP version 4
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IP version 6
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IP v4 address is a 32-bit logical address.
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It is written in decimal format. The 32-bit
address length is divided into 4 equal parts called an octet. Each octet
contains 8 bit and is separated by a dot.
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For example, 192.168.5.10 is an IP v4
address.
Features of IP v4 Address
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IPv4 is a 32-bit length address.
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It is divided into 4 equal parts.
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Each part consists of 8 bits and is called
Octet.
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Each octet is separated by dot notation.
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It is normally written in a human-readable
numbering system ie decimal number.
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232 = 4.7 billion of
addresses are available for IPV4.
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IPv4 consists of two parts: The network
part and the host part.
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The network part shows that the IP address
belongs to which network. The host shows the number of different hosts in the
same network.
IPv4 classes
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Class A address ranges from 0.0.0.0
to 127.255.255.255
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Class B address ranges from
128.0.0.0 to 191.255.255.255
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Class C address ranges from
192.0.0.0 to 223.255.255.255
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Class D address ranges from
224.0.0.0 to 239.255.255.255
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Class E address ranges from
240.0.0.0 to 255.255.255.255
Subnet Mask
The subnet mask is the 32-bit length of
series of binary 0s (zeroes) and 1s (ones) that
distinguishes the network part and
the host part of an IP address. Series of 1s denote
the network portion and 0s denote the host portion.
When we assign an IP address to any host in a network, a
subnet mask is also given to it. For example,
IP address is 192.168.5.10
The subnet mask is 255.255.255.0
If we convert subnet mask to binary bits, then it
looks like this:
11111111.11111111.11111111.00000000
The series of 1s is called the network bits and
the 0s are called host bit.
Network bit will remain unchanged for every IP assigned to
any host in the same network and the network address is derived
by ANDing the binary equivalent of IP address
and the subnet mask.
These series of 0s can be varied from 0s to 1s for
all the hosts within the same network.
Hence, in the above example,
The number of networks is given by = 2n,
where n denotes the number of network bits.
and the number of hosts per network is given by=2h-2 where h is
the number host bit
IPV6
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IPv6 is a 128-bits address having an address
space of 2128, which is way bigger than IPv4. IPv6 use Hexa-Decimal
format separated by colon (:).
1.
There are 8 groups, and each group represents 2
Bytes (16-bits).
2.
Each Hex-Digit is of 4 bits (1 nibble)
3.
Delimiter used – colon (:)
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FE80:CD00:0000:0CDE:1257:0000:211E:729C