UNIT-3

What is a Network Device?

A network device is any hardware component that helps connect computers and other devices in a
network to enable communication and data transfer. These devices can send, receive, and route data between
different parts of a network.
Types of Network Devices and Their Functions
Modem: A modem (short for Modulator-Demodulator) is a network device that converts digital signals
from a computer into analog signals for transmission over telephone or cable lines and vice versa. It acts as a
bridge between your home or office network and the Internet Service Provider (ISP).
Functions of a Modem
 Converts digital data (computer) ↔ analog signals (phone/cable lines).
 Enables internet access via telephone, fiber-optic, or cable networks.
 Compresses and corrects errors in data transmission.
 Assigns public IP addresses for internet connectivity.
Types of Modems
1. Dial-up Modem (Old Technology)
 Uses telephone lines for internet access.
 Slow speeds (up to 56 Kbps).
 Used in early internet connections.
2. DSL Modem (Digital Subscriber Line)
 Uses telephone lines but allows faster speeds than dial-up.
 Speeds range from 1 Mbps to 100 Mbps.
 Used in broadband internet connections.
3. Cable Modem
 Uses coaxial cables for high-speed internet.
 Faster than DSL, reaching 1 Gbps speeds.
 Common in urban areas with cable ISPs.
4. Fiber-Optic Modem
 Uses fiber-optic cables for ultra-fast internet.
 Speeds up to 10 Gbps or more.
 Used in modern high-speed internet services (e.g., Google Fiber).
5. Wireless Modem
 Connects to mobile networks (4G/5G) for internet access.
 Portable and can be used anywhere with a mobile signal.
 Used for travel, remote work, and in areas without wired internet.
How a Modem Works?
 Your computer sends digital data to the modem.
 The modem modulates digital signals into analog signals for transmission over telephone or cable lines.
 The ISP receives and processes the signals, allowing access to websites and services.
 When receiving data, the modem demodulates analog signals back into digital signals for your computer.
Advantages Disadvantages
Easily connects LAN to the internet Serves only as a bridge between LAN and the internet
Converts digital signal into an analog signal Cannot maintain network traffic
Slower speed compared to a hub Unaware of its destination path
HUB: A hub in a computer network is a basic networking device that connects multiple devices in a local
area network (LAN). It operates at the physical layer (Layer 1) of the OSI model and is responsible for
transmitting data packets to all devices connected to it.
Functions of a Hub
 Broadcasts data to all connected devices.
 Does not filter or process data packets.
 Works on a half-duplex mode, meaning only one device can transmit at a time.
 Increases network congestion in large networks.
Types of Hubs

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 Passive Hub – Simply forwards data to all connected devices without amplifying the signal.
Active Hub – Amplifies and regenerates the signal before forwarding it.
Intelligent Hub – Includes management features such as monitoring network traffic and detecting
issues.
Limitations of Hubs
 Increases collision chances (CSMA/CD is required in Ethernet networks).
 Cannot distinguish between devices.
 Slower than switches and routers.
Advantages Disadvantages
Easy to install Cannot filter information
Inexpensive Cannot reduce network traffic
Does not seriously affect network performance Broadcasts data to all ports
SWITCH- A switch in a computer network is a networking device that connects multiple devices within a
local area network (LAN) and uses MAC addresses to forward data only to the intended recipient. Unlike
hubs, which broadcast data to all devices, switches improve network efficiency by sending data directly to
the correct device.
Key Features of a Network Switch:
1. Layer 2 Device: Operates primarily at the Data Link Layer (Layer 2) of the OSI model.
2. MAC Address Table: Stores the MAC addresses of connected devices for efficient data forwarding.
3. Unicast, Broadcast, and Multicast Traffic Handling: Supports different types of communication.
4. Collision Domain Segmentation: Each port has its own collision domain, reducing network
congestion.
5. Full-Duplex Communication: Enables simultaneous sending and receiving of data.
How a Switch Works:
1. A device sends a data frame with the destination MAC address.
2. The switch checks its MAC address table.
3. If the MAC address is known, the switch forwards the frame to the correct port.
4. If unknown, it floods the frame to all ports except the source.
5. Once the recipient responds, the switch updates its MAC address table.
Types of Switches:
1. Unmanaged Switch: Plug-and-play, with no configuration required.
2. Managed Switch: Offers advanced features like VLANs, QoS, SNMP monitoring, and remote
management.
3. Layer 3 Switch: Functions like a router by supporting IP routing along with standard switch
operations.
4. PoE (Power over Ethernet) Switch: Provides power and data through Ethernet cables to devices
like IP cameras and VoIP phones.
Advantages Disadvantages
Increases the available bandwidth of the network More costly than network bridges
Reduces the workload on individual host PCs Broadcast traffic can be problematic
Increases the performance of the network Network connectivity issues are harder to troubleshoot
Router: A router is a networking device that connects multiple networks and directs data packets between
them based on IP addresses. It operates at Layer 3 (Network Layer) of the OSI model and determines the
best path for forwarding data between different networks, such as LANs and WANs or between your home
network and the internet.
Key Functions of a Router
 Packet Forwarding – Determines the best route for data packets based on the destination IP address.
 IP Address Assignment – Uses DHCP (Dynamic Host Configuration Protocol) to assign IP
addresses to devices in a network.
 Network Address Translation (NAT) – Translates private IP addresses to a public IP address for
internet access.
 Firewall and Security – Provides built-in security features like firewalls, access control lists
(ACLs), and VPN support.
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  Interconnecting Networks – Connects different networks, such as home networks to the internet or
office networks to a cloud service.
 Load Balancing – Some routers distribute traffic across multiple internet connections for better
performance.
Types of Routers
 Wired Router – Uses Ethernet cables to connect devices within a network.
 Wireless Router (Wi-Fi Router) – Provides wireless internet access and acts as an access point.
 Core Router – Used in large enterprise networks for handling high-speed data traffic.
 Edge Router – Sits at the boundary of a network and connects to external networks (e.g., ISPs).
 Virtual Router – A software-based router that provides routing functions without dedicated
hardware.
Advantages Disadvantages
Connects various network architectures like
Works only with routable network protocols
Ethernet and Token Ring
Reduces network traffic by creating collision
More expensive than other network devices
and broadcast domains
Chooses the best path across the internetwork
Slower due to analyzing data from layer 1 to layer 3
using dynamic routing algorithms
Repeater: A repeater is a network device that operates at Layer 1 (Physical Layer) of the OSI model and
is used to extend the range of a network by amplifying and regenerating signals before retransmitting them.
It helps overcome signal degradation that occurs over long distances in wired or wireless networks.
Functions of a Repeater
 Signal Amplification: Boosts weak signals to maintain data integrity over long distances.
 Regeneration of Signals: Removes noise and retransmits a cleaner version of the original signal.
 Extends Network Coverage: Allows networks to span larger physical areas without losing signal
strength.
 No Data Processing: Unlike routers and switches, repeaters do not inspect or filter data; they simply
amplify and retransmit it.
Types of Repeaters
1. Wired Repeaters: Used in Ethernet and fiber optic networks to regenerate signals over long cables.
2. Wireless Repeaters (Wi-Fi Extenders): Boost Wi-Fi signals in large buildings or areas with weak
coverage.
3. Optical Repeaters: Used in fiber optic communication to regenerate light signals for long-distance
data transmission.
4. Analog & Digital Repeaters: Analog repeaters amplify all signals, including noise, while digital
repeaters regenerate a cleaner signal.
When to Use a Repeater?
 When a network cable exceeds its standard maximum length (e.g., Ethernet cables beyond 100
meters).
 When a Wi-Fi signal is weak in certain areas of a building.
 In fiber optic networks to maintain data transmission quality over long distances.
 In telecommunication systems to extend mobile network coverage.
Advantages Disadvantages
Simple to set up and inexpensive Cannot connect disparate networks
Does not require additional processing Unable to distinguish between actual signals and noise
Can connect signals with various types of cables Cannot reduce network traffic
Bridge: A bridge is a network device that operates at Layer 2 (Data Link Layer) of the OSI model and is
used to connect two or more LAN segments. It helps in network segmentation by filtering traffic based on
MAC addresses, reducing congestion, and improving performance.
Functions of a Bridge
1. Network Segmentation – Divides a large network into smaller, more manageable segments.
2. Traffic Filtering – Forwards only necessary data between segments based on MAC addresses.
3. Collision Domain Reduction – Helps reduce collisions by creating separate collision domains for
each segment.
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 4. Improves Network Performance – Reduces unnecessary traffic, preventing network congestion.
5. Protocol Independence – Works with different LAN types as long as they use the same Layer 2
protocol (e.g., Ethernet).
Types of Bridges
1. Transparent Bridge – Learns MAC addresses automatically and forwards traffic based on them
without modifying frames.
2. Source Routing Bridge – Used in Token Ring networks, where the sender determines the path of
the packet.
3. Translation Bridge – Connects networks with different protocols, such as Ethernet and Token Ring.
When to Use a Bridge?
 When you need to connect two LAN segments while keeping them in the same network.
 When you want to reduce traffic and collisions in a busy network.
 When you need to connect different types of networks that use the same Layer 2 protocol.
Advantages Disadvantages
Reduces collisions Does not filter broadcasts
Reduces network traffic with minor segmentation More expensive compared to repeaters
Slower compared to repeaters due to the filtering
Connects similar network types with different cabling
process
Gateway in Computer Networks
A gateway is a network device that operates at multiple layers of the OSI model (Layer 3 and above) and
acts as a bridge between different networks that use different communication protocols. It translates data
formats, protocols, or addresses to ensure successful communication between networks.
Functions of a Gateway
1. Protocol Conversion: Translates data between different network protocols (e.g., TCP/IP to X.25).
2. Network Interconnection: Connects different types of networks (e.g., a corporate network to the
internet).
3. Data Format Translation: Converts data between different formats (e.g., email protocol
conversion).
4. Firewall & Security: Some gateways act as firewalls, filtering traffic and providing security
features.
5. VoIP & Telecommunication: Converts voice data between traditional telephony and digital
networks (e.g., VoIP gateways).
Types of Gateways
1. Network Gateway: Connects two different networks, like a corporate LAN to the internet.
2. VoIP Gateway: Converts voice signals between PSTN (Public Switched Telephone Network)
and VoIP.
3. Email Gateway: Converts email messages between different email protocols (e.g., SMTP to X.400).
4. Cloud Gateway: Connects on-premise networks to cloud services.
5. IoT Gateway: Bridges IoT devices and the cloud by handling data filtering, processing, and security.
When to Use a Gateway?
 When you need to connect networks with different communication protocols (e.g., IPv4 to IPv6).
 When integrating legacy systems with modern networks.
 When translating data formats between different applications or devices.
 When connecting on-premise networks to cloud services securely.
Advantages Disadvantages
Broadens the network Does not filter data
Handles traffic issues effectively Costly and difficult to manage
Links two different types of networks Slower transmission rate due to protocol conversion

Network Layer:
The network layer works for the transmission of data from one host to the other located in different
networks. It also takes care of packet routing i.e. selection of the shortest path to transmit the packet, from
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the number of routes available. The sender and receiver’s IP address are placed in the header by the
network layer. Segment in the Network layer is referred to as Packet. Network layer is implemented by
networking devices such as routers and switches.
Services
The network layer in the OSI model provides several critical services to ensure efficient and secure
communication between devices. The services you mentioned—guaranteed delivery, packet delivery within a
bounded delay, and security—are all aspects that some network layer protocols aim to provide.
1. Guaranteed Delivery
 Makes sure data reaches its destination without getting lost.
 Some networks use extra steps like resending lost data to ensure it arrives.
2. Bounded Delay (Limited Time Delivery)
 Ensures that data arrives within a fixed time.
 This is very important for things like video calls or online games, where delays can cause
problems
3. Security
 Protects data from hackers and unauthorized access.
 Uses encryption (coding data) and other security methods like IPsec to keep data safe while
traveling across the network.
Functions
The network layer has several important functions to ensure efficient data transfer between devices.
Here’s a simple explanation of the functions you listed:
Host-to-Host Data Delivery
 Ensures data is transferred from the source device to the destination device, even if they are on
different networks.
 Uses IP addressing to identify devices uniquely.
Logical Addressing
 Assigns unique addresses (such as IP addresses) to each device on a network.
 Helps identify the source and destination of data packets.
Routing and Forwarding
 Routing: Finds the best path for data to travel across multiple networks.
 Forwarding: Moves packets from one router to another until they reach the destination.
Fragmentation
 Breaks large data packets into smaller ones to fit the requirements of different network types.
 The smaller packets are reassembled at the destination.
Congestion Control
 Manages network traffic to prevent overload and delays.
 Uses techniques like traffic shaping and prioritization to ensure smooth data flow.
Advantages:
o Using the network layer in the OSI paradigm offers a multitude of advantages. Let’s delve into
some of these benefits:
o The network layer takes the data and breaks it down into packets, which makes transmitting the
data over the network easier. This process also eliminates any weak points in the transmission,
ensuring that the packet successfully reaches its intended destination.
o Router is the important component of the network layer . Its role is to reduce network congestion
by facilitating collisions and broadcasting the domains within the network layer.
o Used to send data packets across the network nodes, the forwarding method is various.
Limitations:
 There is no flow control mechanism provided by the network layer design.
 There may be times when there are too many datagrams in transit over the network, causing
congestion. This could put further strain on the network routers. In some circumstances, the router
may lose some data packets if there are too many datagrams. Important data may be lost in the
process of transmission as a result of this.

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  Indirect control cannot be implemented at the network layer since the data packets are broken up
before being sent. Additionally, this layer lacks effective error control systems.
Network Layer (Layer 3) protocols: The Network Layer (Layer 3) protocols are responsible for
addressing, routing, and forwarding data across different networks. These protocols help ensure seamless
communication between devices by defining how data packets are addressed, transmitted, and received.
1. Internet Protocol (IP)
The Internet Protocol (IP) is the primary protocol of the network layer, responsible for identifying and
addressing devices on a network.
Versions of IP:
 IPv4 (Internet Protocol Version 4)
o Uses 32-bit addresses (e.g., 192.168.1.1).
o Supports approximately 4.3 billion unique addresses.
o Uses fragmentation when packets exceed the MTU.
o Supports protocols like ARP, ICMP, RIP, and OSPF.
 IPv6 (Internet Protocol Version 6)
o Uses 128-bit addresses (e.g., 2001:db8::1).
o Provides a much larger address space than IPv4.
o Eliminates the need for NAT by allowing more direct communication.
o Uses ICMPv6 for error handling and address resolution.
2. Address Resolution Protocol (ARP)
 Converts an IP address into a MAC address (used in local networks).
 Example Use Case:
o If a computer wants to send data to 192.168.1.10, ARP finds the MAC address of that
device.
 Types of ARP Messages:
o ARP Request: "Who has IP 192.168.1.10? Tell me your MAC address."
o ARP Reply: "I am 192.168.1.10, my MAC address is 00:1A:2B:3C:4D:5E."
3. Reverse Address Resolution Protocol (RARP)
 Finds the IP address of a device given its MAC address.
 Used in diskless workstations that do not have a stored IP address.
 Replaced by DHCP in modern networks.
4. Internet Control Message Protocol (ICMP)
 Used for error reporting and network diagnostics.
 Helps in troubleshooting network issues.
 Example Use Cases:
o Ping Command (Checks if a device is reachable).
o Traceroute Command (Finds the path packets take to a destination).
 ICMPv6 is used in IPv6 networks for similar purposes.
5. Internet Group Management Protocol (IGMP)
 Used for multicasting (sending a packet to multiple recipients).
 Allows devices to join or leave multicast groups.
 Example Use Case:
o Streaming services like Netflix use IGMP to deliver video content to multiple users
efficiently.
6. Network Address Translation (NAT) Protocol
 Converts private IP addresses into public IP addresses for internet access.
 Helps conserve IPv4 addresses and enhances security.
 Types of NAT:
o Static NAT – One-to-one mapping of private and public IPs.
o Dynamic NAT – Assigns a public IP from a pool.
o PAT (Port Address Translation) – Multiple private IPs share a single public IP.

TCP/IP (Transmission Control Protocol/Internet Protocol):

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 TCP/IP (Transmission Control Protocol/Internet Protocol) is the fundamental suite of networking
protocols that enables communication over the internet and most local networks. It defines how data is sent,
addressed, transmitted, routed, and received between devices.

TCP/IP is based on the client-server communication model, which means that a user of a first computer (the
client) sends a service request to a second network computer or web hosting provider(server), such as
forwarding a Web page. TCP/IP also uses point-to-point communication, which means that data is sent from
one host computer to another within a defined network border. In TCP/IP model, each client request is
unique and unrelated to previous ones. Hence, it is called stateless, and being stateless allows network
channels to be used indefinitely.
Because the entire process is standardized, the TCP/IP model works. Without standardization,
communication would go haywire, and fast internet service relies on efficiency. The TCP/IP model provides
both efficiency and standardization. The TCP/IP model is the most effective way to send internet data
because it is the global standard.
Highlights:
 According to the four-layered architecture, the TCP/IP model divides the data into packets.
 The TCP/IP model provides both efficiency and standardization, and it is one of the biggest reasons
why the TCP/IP model always works.
Layers in TCP/IP Model
The TCP/IP model generally consists of four essential layers
1. Application Layer
2. Host-To-Host Layer/Transport Layer
3. Internet Layer/Network Layer
4. Network Access Layer/Link Layer
Uses of the TCP/IP Model
The TCP/IP model serves as the foundation for internet communication, providing a standardized suite of
protocols for data exchange between devices. Some key applications include:
1. Internet Communication – Enables web browsing, email, and file transfers, making the internet
possible.
2. Text Communication – Ensures reliable, error-free delivery for messaging apps like WhatsApp,
Instagram, Google Chat, and iMessage.
3. Internet Banking – Provides security, reliability, and efficiency, making online transactions safe.
4. Online Gaming & Video Streaming – Supports both connection-oriented (TCP) and connectionless
(UDP) transmission, enabling seamless content delivery.
5. Network Services – Facilitates essential services like DNS (Domain Name System), DHCP
(Dynamic Host Configuration Protocol), VPNs (Virtual Private Networks), and error control
mechanisms.
Advantages of the TCP/IP Model
 Open Standard – Not owned by any institution, making it freely accessible.
 Scalable & Flexible – Supports new networks and devices without disrupting existing
infrastructure.
 Interoperability – Allows communication between different devices and operating systems.
 Reliable Communication – Ensures data integrity and proper sequencing.
 Unique Addressing – Assigns unique IP addresses for easy identification of devices.
 Supports DNS – Translates human-readable domain names into numerical IP addresses, simplifying
navigation.

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Disadvantages of the TCP/IP Model
 Lack of Layer Separation – Does not clearly distinguish between services, interfaces, and
protocols.
 Not Optimized for Small Networks – Designed for large-scale networks, making it inefficient for
LANs and PANs.
 Limited to TCP/IP Stack – Cannot define other networking protocols like Bluetooth.
 Difficult to Replace Protocols – Once implemented, replacing or updating protocols is complex.
IP Address class:
An IP (Internet Protocol) address is a unique 32-bit identifier that allows communication between
devices over a network. It provides information on how to reach a specific host, particularly outside a Local
Area Network (LAN). The address space of IPv4 consists of 2³² (4,294,967,296) unique addresses.
Classes of IP Addressing
IPv4 addresses are divided into five classes:
 Class A
 Class B
 Class C
 Class D (Reserved for Multicast)
 Class E (Reserved for Experimental use)
The class of an IP address determines:
 The number of bits used for network ID and host ID
 The total number of possible networks and hosts in each class
Each Internet Service Provider (ISP) or network administrator assigns an IP address to every connected
device.
Classful Addressing
Historically, IPv4 addresses were divided into distinct classes based on the first few bits of the address.
Address Space Allocation in Classful Addressing
Class A
 Range: 1.0.0.0 to 127.255.255.255
 Default Subnet Mask: 255.0.0.0 (/8)
 First Octet: Starts with 0, allowing values from 1 to 127
 Purpose: Used for very large networks, supporting approximately 16 million hosts per network
 Special Note: The 127.x.x.x range is reserved for loopback addresses (e.g., 127.0.0.1 refers to the
device itself)
Class B
 Range: 128.0.0.0 to 191.255.255.255
 Default Subnet Mask: 255.255.0.0 (/16)
 First Octet: Starts with 10, allowing values from 128 to 191
 Purpose: Suitable for medium to large-sized networks, supporting around 65,000 hosts per
network
Class C
 Range: 192.0.0.0 to 223.255.255.255
 Default Subnet Mask: 255.255.255.0 (/24)
 First Octet: Starts with 110, allowing values from 192 to 223
 Purpose: Used for smaller networks, supporting up to 254 hosts per network
Class D (Multicast)
 Range: 224.0.0.0 to 239.255.255.255
 Purpose: Reserved for multicast communication, where data is sent from one sender to multiple
receivers instead of broadcasting to all devices.
Class E (Experimental)
 Range: 240.0.0.0 to 255.255.255.255
 Purpose: Reserved for experimental and future use. These addresses are not used for regular IP
addressing.

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Subnet Mask
A subnet mask is a 32-bit number used in IP addressing to separate the network portion of an IP
address from the host portion. It helps computers and devices determine which part of an IP address refers
to the network they are present, and which part refers to their specific location or address within that
network.
Sub netting is the process of dividing a larger network into smaller, more manageable subnetworks
(subnets). It helps optimize IP address allocation, improve network security, and enhance performance by
reducing congestion.
Major Motivations for Using Subnetting
Subnetting is a crucial networking technique that helps optimize and manage IP address allocation
effectively. Below are the main reasons for using subnetting:
1. Reallocation of IP Addresses
o Subnetting allows better distribution of IP addresses by breaking large networks into smaller
sub networks.
o Prevents wastage of IPs, especially in IPv4, where addresses are limited.
o Enables organizations to efficiently assign IPs based on their needs.
2. Improving Network Speed
o Reduces the size of broadcast domains, preventing excessive traffic from slowing down the
network.
o Enhances overall performance by limiting unnecessary communication between devices in
different subnets.
o More efficient routing, as routers handle smaller subnet tables instead of massive networks.
3. Enhancing Network Security
o Segments networks into smaller parts, reducing the risk of unauthorized access across
different departments.
o Allows the implementation of security policies for each subnet (e.g., firewalls, access
controls).
o Limits the spread of cyber threats, such as malware or attacks, to only a specific subnet.
4. Relieving Network Congestion
o Reduces unnecessary traffic by containing broadcasts within smaller subnets.
o Helps balance network loads by dividing traffic across multiple segments.
o Prevents network slowdowns caused by excessive device communication.
5. Increasing Efficiency in Network Management
o Makes troubleshooting easier by isolating network issues within a specific subnet.
o Enables better organization of networks for different departments, locations, or functions.
o Allows efficient use of resources like DHCP servers by restricting their scope to specific
subnets
Advantages of Subnetting
 Efficient IP Address Usage – Prevents wastage of IP addresses.
 Improved Security – Isolates network segments and limits unauthorized access.
 Reduced Network Congestion – Minimizes unnecessary traffic and broadcasts.
 Better Network Management – Easier troubleshooting and organization.
 Enhanced Performance – Smaller subnets mean faster communication.
Disadvantages of Subnetting
 Increases Complexity – Requires planning and technical expertise.
 More Router Processing – Larger routing tables can slow down performance.
 Wasted IPs – Network and broadcast addresses reduce usable IPs.
 Higher Maintenance – More configuration and administrative effort.
 Inter-Subnet Communication Needs Routers – Devices in different subnets require routers
to communicate.

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IP (Internet Protocol):
IP stands for Internet Protocol. Internet Protocol helps to uniquely identify each device on the
network. Internet protocol is responsible for transferring the data from one node to another node in the
network. Internet protocol is a connectionless protocol therefore it does not guarantee the delivery of data.
The Internet Protocol is divided in two types. They are:
IPv4: IP stands for Internet Protocol version v4 stands for Version Four (IPv4), is the most widely used
system for identifying devices on a network. It uses a set of four numbers, separated by periods (like
192.168.0.1), to give each device a unique address. This address helps data find its way from one device to
another over the internet.
Parts of IPv4: IPv4 addresses consist of three parts:
1. Network Part: The network part indicates the distinctive variety that's appointed to the network.
The network part conjointly identifies the category of the network that's assigned.
2. Host Part: The host part uniquely identifies the machine on your network. This part of the IPv4
address is assigned to every host.
For each host on the network, the network part is the same however, the host half must vary.
3. Subnet Number: This is the nonobligatory part of IPv4. Local networks that have massive numbers
of hosts are divided into subnets and subnet numbers are appointed to that.
Characteristics of IPv4:
➤ IPv4 could be a 32-bit IP Address.
➤ IPv4 could be a numeric address, and its bits are separated by a dot.
➤ The number of header fields is twelve and the length of the header field is twenty.
➤ It has Unicast, broadcast, and multicast-style addresses.
➤ IPv4 supports VLSM (Virtual Length Subnet Mask).
➤ IPv4 uses the Post Address Resolution Protocol to map to the MAC address.
➤ RIP may be a routing protocol supported by the routed daemon.
➤ Networks ought to be designed either manually or with DHCP.
➤ Packet fragmentation permits from routers and causes host.
IPv4 Address Format:
IPv4 Address Format is a 32-bit Address that comprises binary digits separated by a dot (.).
10000000 00001011 00000011 00011111

128.11.3.31
Advantages of IPv4
➤ IPv4 security permits encryption to keep up privacy and security.
➤ IPV4 network allocation is significant and presently has quite 85000 practical routers.
➤ It becomes easy to attach multiple devices across an outsized network while not NAT.
➤ This is a model of communication so provides quality service also as economical knowledge transfer.
➤ IPV4 addresses are redefined and permit flawless encoding.
➤ Routing is scalable and economical as a result of addressing its collective more effectively.
➤ Data communication across the network becomes a lot of specific in multicast organizations.
Drawback of IPv4
 Limited Addresses – There aren’t enough IPv4 addresses for all the devices in the world.
 Complicated Setup – Setting up IPv4 can be tricky and sometimes needs manual work.
 Slower Routing – IPv4 isn’t the best at finding the fastest path for data.
 Weak Security – IPv4 doesn’t have built-in security, making it easier for hackers to attack.
 Poor Quality Control – It struggles to prioritize important data, which can cause issues with video
calls and online games.
 Data Splitting Issues – Sometimes, IPv4 breaks data into smaller pieces, which can slow things
down or cause errors.
 Wastes Network Resources – IPv4 sends messages to many devices at once, creating unnecessary
network traffic.
IPv6: Internet Protocol (IP), which is the system used for identifying and locating computers on the Internet.
IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the problem of IPv4
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exhaustion. IPv6 is a 128-bit address having an address space of 2128 which is way bigger than IPv4, IPv6
uses a Hexa-Decimal format separated by a colon (:).
IPv6 Address Format:
 There are 8 groups and each group represents 2 Bytes (16-bits).
 Each Hex-Digit is of 4 bits (1 nibble)
 Delimiter used - colon (:)
ABCD: EF01: 23456789: ABCD: B201 : 5482:
D023
16 Bytes
Need For IPv6:
1. More IP Addresses – IPv6 uses 128-bit addresses, providing a huge number of unique addresses to
support the growing number of devices, including IoT.
2. Faster Routing – IPv6 has a simpler header, which helps routers process data more efficiently.
3. Better Features – New options in IPv6 improve flexibility and allow for advanced networking
capabilities.
4. Future-Proof – IPv6 is designed to be expandable, so it can adapt to new technologies without
major changes.
5. Better Performance – IPv6 prioritizes important data like video calls and streaming, improving
quality.
6. Stronger Security – IPv6 has built-in encryption and authentication, making it more secure than
IPv4.IPv6 Addressing Methods:
IPv6 supports three types of addresses, which provide more flexibility in how data is delivered across the
network:
 Unicast – Sends data to one specific device. (Like mailing a letter to one person.)
 Multicast – Sends data to multiple devices at once. (Like broadcasting a TV signal to many
viewers.)
 Anycast – Sends data to the nearest device in a group. (Like ordering food from the closest
restaurant.)
Advantages of IPv6
1. Faster Data Transmission – Supports real-time streaming with minimal delay.
2. Built-in Authentication – Ensures that data comes from the right sender and is not altered by third
parties.
3. Stronger Encryption – Encrypts data at the network layer, even if applications do not provide
encryption.
4. Faster Routing – Uses a fixed 40-byte header, making data processing quicker and more efficient
compared to IPv4.
Disadvantages of IPv6
1. Slow Transition – Since IPv4 is widely used, switching to IPv6 will take a long time.
2. Compatibility Issues – IPv4 and IPv6 devices cannot communicate directly, requiring extra
setup.
3. No Backward Compatibility – IPv6 does not work on older IPv4-only devices.
4. Conversion Complexity – Transitioning to IPv6 requires major infrastructure changes.
5. Protocol Isolation – IPv4 and IPv6 operate separately, creating communication barriers.

Difference Between IPv4 and IPv6

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 Feature IPv4 IPv6
Address Length 32-bit 128-bit
Numeric, separated by dots (e.g., Hexadecimal, separated by colons (e.g.,
Address Format
192.168.1.1) 2001:db8::1)
Number of
~4.3 billion Virtually unlimited
Addresses
Header Size 20-60 bytes (variable) Fixed 40 bytes
No built-in security (relies on external
Security Built-in encryption and authentication
security like IPsec)
Slower due to complex headers and
Routing Speed Faster due to a simplified header
fragmentation
Address
Manual or DHCP Auto-configuration using SLAAC
Configuration
Broadcasting Supports broadcasting No broadcasting, uses multicast instead
Not fully compatible with IPv4 without
Compatibility Supported by most networks
transition mechanisms
Quality of Service Improved support with Traffic Class &
Limited support
(QoS) Flow Label
ARP (Address Resolution Protocol)
ARP is a network protocol used to find the MAC address of a device when its IP address is known.
 It enables communication between devices in a Local Area Network (LAN) by resolving IP
addresses to MAC addresses.
 Defined in RFC 826 (1982), it is a critical part of the TCP/IP protocol suite and operates at the
Data Link Layer (Layer 2).
Why is ARP Needed?
 While IP addresses are used for communication over networks, actual data transmission happens
using MAC addresses at the data link layer.
 When sending data, a device needs the MAC address of the destination, which is resolved using
ARP.
How ARP Works: When a sender device needs to communicate with another device
1. Check the ARP Cache
o If the destination's MAC address is already stored, use it.
o If not, proceed to send an ARP request.
2. Send an ARP Request (Broadcast)
o The sender broadcasts an ARP request to all devices on the LAN.
o This message contains:
 Sender’s IP & MAC address.
 Receiver’s IP address (MAC left empty, since it's unknown).
3. Receive ARP Request & Send ARP Reply (Unicast)
o The device with the matching IP responds with an ARP Reply, providing its MAC address.
4. Update ARP Cache
o Both sender and receiver update their ARP Cache with the new MAC-IP mapping for future
use.
Types of ARP

1. Proxy ARP
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  Used by a router to respond to ARP requests on behalf of devices in another network.
 Helps connect different subnets without requiring manual configuration.
2. Gratuitous ARP
 A device sends an ARP request for its own IP to detect IP conflicts or update other devices' ARP
caches.
3. Reverse ARP (RARP)
 Used by devices (without an IP) to request their IP address from a RARP server using their MAC
address.
 Obsolete and replaced by DHCP.
4. Inverse ARP (InARP)
 Opposite of ARP: Finds an IP address when the MAC address is known.
 Used in Frame Relay and ATM networks.
ARP Packet Format

Field Size Description

Hardware Type 2 bytes Defines the network type (Ethernet = 1)
Protocol Type 2 bytes Identifies the protocol (IPv4 = 0x0800)
Hardware Address Length 1 byte Size of the MAC address (6 bytes for Ethernet)
Protocol Address Length 1 byte Size of the IP address (4 bytes for IPv4)
Opcode 2 bytes 1 = Request, 2 = Reply
Sender MAC Address 6 bytes Sender’s MAC address
Sender IP Address 4 bytes Sender’s IP address
Target MAC Address 6 bytes Receiver’s MAC (blank in requests)
Target IP Address 4 bytes Receiver’s IP address
Advantages of ARP
 Automatic MAC Resolution: No manual configuration needed.
 Fast Communication: Once resolved, MAC addresses are stored in the cache for quick access.
 Supports Different Network Technologies: Works with Ethernet, Frame Relay, ATM, etc.
 Essential for Network Functioning: Without ARP, devices wouldn’t be able to communicate using
TCP/IP.
Disadvantages of ARP
 With ARP, there are some attacks on Ethernet networks, such as ARP spoofing and denial of
services.
 In large networks, ARP can cause traffic slowdowns due to how it communicates.
 If your network setup changes, ARP can be slow to catch up.

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