Network Protocols C02

Introduction

A network protocol is a set of guidelines that enable devices in a network to communicate with each other. It allows devices to communicate, even if the devices inside the network operate differently or look different. Network protocols make it easier for people to communicate with people all over the world. Network protocols are essential for modern digital communication. Network protocols simplify large processes by breaking them down into smaller, individual tasks. This is done at every network level. Each task must work together at every level to complete the larger task. When we say 'protocol suite', we mean a collection of smaller network protocols that work together.

Application.

The application layer is where end-user software, like web browsers and email, clients, operates. It offers protocols that let software send and get information and show useful data to users.

Examples:

HTTP (Hypertext Link Protocol)

FTP (File Transfer Protocol)

DNS (Domain Name System)

SMTP (Simple Mail Transfer Protocol)

POP (Post Office Protocol)

HTTP

Stands for Hypertext Link Protocol.

Hypertext refers to the existence of documents or files that contain text, images, video, or other multimedia content. Transfer refers to the ability of these files to be transferred between networked devices on the Web. Protocol refers to a set of rules that govern communication within networks.

Client computers talk to web servers by sending HTTP requests and getting back HTTP response.

HTTPS (Hypertext Transfer Protocol Secure) is created by combining the HTTP (Hypertext Link Protocol) with the SSL (Secure Socket Layer)/TLS (Transport Layer Security) protocol for added security.

TLS is an authentication and security protocol widely implemented in browser and web server.

FTP

FTP, short for File Transfer Protocol, is a set of protocols that govern how files are exchanged between computers over the Internet. Businesses use FTP to send files between computers, and websites use FTP to send and receive files from and to their web servers.

FTP operates by establishing two connections between the computers that are attempting to interact. The data transfer is handled by one channel, and the other is used for the orders and responses that are transmitted back and forth between the two clients. The communicating computers, servers, or proxy servers employ four commands during an FTP transmission that are send, get, change directory, and transfer.

Block, stream, and compressed are the three modes that FTP uses while sending files. FTP may manage data in a string of data without any boundaries when using the stream mode.

DNS

DNS Resolves Domain Names to IP Addresses: DNS is responsible for transforming domain names into their corresponding IP addresses. When you type a URL such as "www.example.com" into your web browser, DNS helps the browser discover the IP address associated with that domain name, enabling it to establish a connection to the web server hosting the website.

IP Addresses Facilitate Communication: IP addresses act as unique identifiers for internet-connected devices, allowing data packets to be directed from one device to another across the internet. Every internet-enabled device, be it a computer, smartphone, or server, possesses a unique IP address that permits other devices to locate and communicate with it.

DNS Simplifies Accessibility: DNS servers eliminate the need for individuals to memorize intricate numerical IP addresses. Instead, we can employ user-friendly domain names to access internet resources, websites, and services. DNS serves as an intermediary by covertly associating these domain names with the corresponding IP addresses

SMTP

The Simple Mail Transfer Protocol (SMTP) is a set of rules for communication that enables applications to send electronic mail over the internet. This software allows you to send messages to other computer used based their email addresses.

It facilitates sending a single message to one or more recipients and enables mail exchange between users using the same or other machines. Messages can be sent using text, audio, video, or graphics. The message may also be transmitted through networks other than the internet.

SMTP is mostly used to establish communication rules between servers. The servers. have a method of identifying themselves and making known the type of communication they are attempting. Additionally, the offer a method for dealing with mistakes like an erroneous email address. For instance, the receiving server may respond with an error message if the recipient address is incorrect.

POP

The complete name of the protocol is Post Office Protocol. As commonly understood, SMTP functions as a message transfer agent. When a message is dispatched, SMTP serves to move it from the sender's client to the server, which subsequently forwards it to the recipient server.

However, the Message Access Agent assists in retrieving the message from retrieving the message from the receiving server. POP3 and IMAP are the two types of protocols that are included in the Message Access Agent.

Telnet

A standard mechanism for interacting with the terminal devices and terminal oriented operation is provided by the Telnet Protocol (TELNET).

Programs that emulate terminals and let you connect into distant host frequently into distant hosts frequently use TELNET. TELNET, however, can also be used for inter-process communication ad terminal-to terminal communication. Other protocols (like FTP) can also establish a protocol channel using TELNET.

In the tn, telent, or tn3270 user commands, TCP/IP implements TELNET. There is no TELNET API provided by the telnetd daemon.

Transport Layer

In the TCP/IP model, Transport Layer is the second layer, while in the OSI model, it is the fourth layer.

To ensure message delivery to a host, it operates as an end-to-end layer, establishing a direct connection between the source and destination hosts instead of a step-by-step connection. This reliability in delivering services is what characterizes it as an end-to-end layer. Within the Transport Layer, a segment serves as the fundamental data encapsulation unit.

On the sender's end, the transport layer gets the data from the application layer, conducts segmentation, splits the message into its component part, appends the source and destination ports to each segment's header and then sends the message to the network layer.

The transport layer receives data from the network layer, segments it, reads its header, determines the port number, and then passes the message to the correct port in the application layer.

1. TCP

Layer 4 protocol TCP sends out duplicates of any lost packets and offers acknowledgement of the received packets.

Although it is superior to UDP, these features come at an added overhead. Application protocol like HTTP and FTP make use of it.

TCP relies on a three-way handshake synchronization, acknowledgement and final acknowledgement as depicted.

2. UDP

While it belongs to the same layer 4 protocol category as TCP, UDP does not include packet acknowledgment. Consequently, it lacks reliability and relies on higher-layer protocols for this function. However, in contrast to TCP, UDP is less complex, more adaptable, and imposes fewer additional data burdens. It finds common usage in both voice and video streaming.

Network Layer Protocol

Even though UDP is a layer 4 protocol, it differs from TCP in that it does not offer packet acknowledgement.

It is untrustworthy and is dependent on the procedures at higher layer for the same. However, compare to TCP, it has less overhead, is simple to scale, and is simpler.

Audio and video streaming both make use of it.

1. ARP

Address Resolution Protocol (ARP) is utilized to link the MAC address and IP address.

The MAC address encoded on the NIC identifies every device connected to the network. As a result, we may state that devices on a local area network requires the MAC address to communicate. It is simple to modify a MAC address.

For instance, when a machine's NIC malfunctions, the MAC address changes but the IP address does not. When an internet address is known, ARP is used to determine the node's MAC address.

2. RARP

Reserve Address Resolution Protocol (RARP) is the name of the protocol used to obtain an IP address from a server.

When a host requests information from the network, such as its IP address, it broadcasts a RARP inquiry packet containing its physical address. The host IP address is returned in response once a networked RARP server identifies the RARP packet.

The RARP protocol's message structure is comparable to that of a ARP protocol. Similar to an ARP frame, a RARP frame is transmitted from one machine to another enclosed in a frame's data.

3. ICMP

Internet Control Message Protocol (ICMP) is used in order to notify the sender of IP datagram issues, hosts and routers employ the ICMP protocol at the network layer.

To determine whether the destination is reachable and responding, ICMP performs an echo test. Although ICMP can handle both control and error messages, its primary job is to report errors rather than fix them.

Although an IP datagram carries the addresses of its source and destination, it is unaware of the previous router it has travelled through. As a result, ICMP can only deliver messages to the source and not to nearby routers.

The sender receives the error messages using the ICMP protocol. Errors are returned to the user processes as a result of ICMP packets, IP datagrams are used to transmit ICMP messages.

4. IGMP

Internet Group Message Protocol (IGMP) has two modes of communication that are supported by the IP protocol:

A communication method known as 'unicasting' has only one sender and one receiver. we can therefore define it as one-to-one communication.

On occasion, the sender desires to send the same message to many recipients at once. Multicasting, which uses one-to-many communication, is the name of this process.

The host and router both use the IGMP protocol to support multicasting.

The hosts and router use the IGMP protocol to identify the host in a LAN that are a part of a group.

5. IP

The Internet Protocol (IP) is a protocol or a collection of guidelines, for addressing and routing data packets so they can move between networks and reach their intended location. The internet divides data into smaller units known as packets for transmission.

Each packet contains IP information, which enables routers to send packets to the appropriate location.

Every device or domain that connects to the internet is given an IP address, and data gets to the right place as packets are sent to the IP address associated with them.

Network Access Layer

At the base of the TCP/IP hierarchy lies the Network Access tier. The protocols within this layer provide the necessary capabilities for a system to transmit data to other devices on the same network to which it is directly linked. This layer defines the methods for sending an IP packet across the network.

Unlike protocols at higher layers, Network Access Layer Protocols must have knowledge about the details of the underlying network, including its addressing, packet structure, and so on. This knowledge is essential for formatting the data being transmitted in a manner that aligns with the specific requirements of the network.

All of the operations performed by the Data Link and Physical layers at the bottom of the OSI reference model can be included in the TCP/IP Network Access Layer.

1. Ethernet

Local area networks are primarily built using Ethernet, a standard communication protocol. Through cables, it sends and receives data.

This makes it easier to communicate over a network using two or more distinct types of connections, such as copper to fiber optic and the other way around.

2. Ethernet Types

Fast Ethernet: Fast Ethernet can achieve data transfer speeds of up to 100 Mbps. It typically utilizes twisted pair or CAT5 cables for network support.

Gigabit Ethernet: This network type offers even faster data transmission, with speeds around 1000 Mbps or 1 Gbps. It's an improvement over Fast Ethernet and is influenced by all four pairs in a twisted pair cable.

10 Gigabit Ethernet: 10 Gigabit Ethernet represents a more advanced and high-speed network. It can support data transfer rates up to 10,000 Mbps and can cover longer distances when using fiber optic cables, extending up to approximately 10,000 meters.

Switch Ethernet: In this network type, a switch or hub is required. Instead of relying on a standard twisted pair connection, it employs a different networking approach for data transfer.

IP Address

An internet-connected device or domain is assigned a unique identifier known as an IP address. These IP addresses are represented as strings of characters, such as "192.168.1.1." Thanks to DNS resolvers, users can access websites without the need to remember these lengthy character strings because DNS translates human-readable domain names into IP addresses.

In a manner akin to how a piece of mail contains both the destination address and the return address, each IP packet carries both the IP address of the device or domain sending the packet and the IP address of the intended recipient.

Type of IP Address

IP addresses come in four varieties: public, private, static and dynamic. While the terms public and private describes where a network is located, Public is used outside of a network while private is used inside a network.

An IP Address that is static was manually generated rather than being assigned. A static IP address is also permanent, in contrast to a dynamic IP address, which is given by a DHCP server and is susceptible to change.

The most typical kind of internet protocol addresses are dynamic IP addresses. Unlike static IP addresses, dynamic IP addresses have a limited lifespan and eventually expire. Either the computer will automatically request a new lease or a new IP address might be assigned to it.

Classes of IP Address

Classes A, B, C, D and E are the five IP addresses classes that TCP/IP specifies. There is a range of legal IP addresses for each class.

The class is determined by the first octet's value.

Host addresses can be created using IP addresses from the first three classes (A, B, and C).

Class D is used for multicast and class E is utilized for experimental purposes. The other two classes are used for different things.

Class A starts from 0 ends at 127, B at 191, C at 223, D at 239 and E at 256.

SUBNETTING

The process of logically dividing a single physical network into numerous smaller sub-networks or subnets is known as subnetting.

The client or host address and the server or network addresses are the two halves of every device's IP address. IP addresses can either be set manually (static IP addresses) or by a DHCP server.

The subnet mask separates the IP address into host and network addresses, indicating which portions belong to the device and which portions belong to the network.

Local devices are connected to other networks through the equipment known as a gateway or default gateway. This means that a local device must submit its packets before they may be forwarded to their intended recipient outside of the local network when it wishes to communicate information to a device with an IP address on another network.

SUBNET MASK

On an IP network, a single device is uniquely identified by its 32-bit IP address. The subnet mask divides the 32-bit IP address. The subnet mask divides the 32 binary bits into host and network portions, but they are also separated into four *-bit octets.

A broadcast address is always associated with the '255' address, while a network address is always associated with the '0' address. Both are set aside for these specific uses, hence neither can be allocated to hosts.

Most networks employ the Internet Protocol as the underlying structure to enable device communication, which is made up of the IP address, subnet mask, and gateway or router.

subnetting further separates the host element for the IP address into a subnet when companies want more sub networking. Subnet masks just serve to make the subnetting process possible.

 

Classful Routing

Subnet masks are not imported by Classful Routing. Subnet mask is also provided in this case following the route modification.

A method of allocating IP addresses called classful addressing divides addresses into five main categories.

Subnet musk in classful routing is constant across all devices and does not change.

Variable Length Subnet Mask (VLSM) and Classless Inter-Domain Routing (CLDR) are not supported in Classful Routing.

Classless Routing

In order to slow down the rapid expiration of IP addresses, classless addressing will eventually take the place of classful addressing.

Subnet mask is imported by classless routing, which makes use of tigered updates. VLSM and CLDR are supported in classless routing.

Hello messages are used to status checking in classes routing. In classless routing, subnet masks may not always be the same foe all devices.

Variable Length Subnet Mask (VLSM)

In VLSM, the subnet design employs several masks within a single network that is multiple masks are utilized for various subnets within a single class A, class B, or network.

Due to varying size of subnets, it is utilized to make them more usable. Additionally, it is described as the procedure of subnetting a subnet.