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

•        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:

•        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):

•        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):

•        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

•        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:

•        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

•        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.

•         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.

•        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.

•        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

•        The OSI model helps users and operators of computer networks:

•        Determine the required hardware and software to build their network.

•        Understand and communicate the process followed by components communicating across a network. 

•        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:

•        Create devices and software that can communicate with products from any other vendor, allowing open interoperability

•        Define which parts of the network their products should work with.

•        Communicate to users at which network layers their product operates – for example, only at the application layer, or across the stack.

 

 

 

IP address

 

•        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.

•        IP version 4

•        IP version 6

•        IP v4 address is a 32-bit logical address.

•        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.

•        For example, 192.168.5.10 is an IP v4 address.

 

Features of IP v4 Address

•        IPv4 is a 32-bit length address.

•        It is divided into 4 equal parts.

•        Each part consists of 8 bits and is called Octet.

•        Each octet is separated by dot notation.

•        It is normally written in a human-readable numbering system ie decimal number.

•        2³² = 4.7 billion of addresses are available for IPV4.

•        IPv4 consists of two parts: The network part and the host part.

•        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

•        Class A address ranges from 0.0.0.0 to 127.255.255.255

•        Class B address ranges from 128.0.0.0 to 191.255.255.255

•        Class C address ranges from 192.0.0.0 to 223.255.255.255

•        Class D address ranges from 224.0.0.0 to 239.255.255.255

•        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=2^h-2 where h is the number host bit

 

IPV6

•        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 (:)

•        FE80:CD00:0000:0CDE:1257:0000:211E:729C