Section 13 Network protocols-osi-tcp

Be familiar with common networking transport protocols

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Be familiar with common networking transport protocols

state what is meant by a network protocol

Networking protocols

Networking protocols provide the rules and standards for communication between network devices.

Networking protocols

For example, they allow devices to identify one another and connect, and specify how data is sent and received between the devices.

list the ‘well known’ protocols to include TCP/IP, UDP, DNS, DHCP, POP, ICMP, FTP .. distinguish between protocols in terms of data transportation over the network

Why did Facebook go down in 2021

Because of BGP Protocol failure
What is BGP
https://www.cloudflare.com/learning/security/glossary/what-is-bgp/
A video explaining what face book went down
https://www.youtube.com/watch?v=KU7uyi09Esw

Web Protocols

TLS is the newer version of SSL(Secure Socket Layer) a cryptographic protocol that provides

secure communication over a computer network

Email Protocols

SMTP for sending emails POP3 used to download emails from mail server and

IMAP allows you to access emails from multiple devices, MME it allows yoy to add images, videos to emails as attatchements

File Transfer Protocols

Theses are ways of transferring information through a network

Media Protocols

Management Protocols

PuTTY is a pretty common terminal program. Simple Network Management Protocol,SNMP,

Remote Desktop Protocol RDP

Common Protocols

NetBIOS for Windows name resolution. NTP for getting the time so that you can make sure you have an accurate time.

LDAP, this is a directory structure. LDAP allows us to have a scheme for compartmentalization of users and

groups and domains. And we use that sort of technology in things like Windows Active Directory.

Networking protocols

TCP/IP is a suite of networking protocols that enables communication on networks. In a TCP/IP network, a connection-oriented protocol has to establish a logical connection before a host can send data. Once the data has been transmitted, the connection is released.
A connectionless protocol doesn't need a logical connection to transmit data. Information is transmitted from a source to a destination without checking whether the destination host is prepared to receive the information.

Networking protocols

At the Internet layer of the TCP/IP suite, IP is a connectionless protocol that's responsible for addressing and relaying data packets.

IP acts like an intermediary between higher protocol layers and a network. It doesn't guarantee packet delivery or check for lost or corrupted packets.

Networking protocols

A TCP/IP system uses one of two protocols – TCP and UDP – which work together with IP to transfer data.

Networking protocols

TCP is a connection-oriented protocol that helps ensure reliable data delivery. It sends data, waits for an acknowledgement, and fixes erroneous data. It breaks data into datagrams, reassembles datagrams when they reach their destination, resends any data lost in transit, and re-sequences data.

Uses:

Web browsing, file transfers, email, and applications requiring guaranteed data integrity.

Networking protocols

UDP is a connectionless protocol. Unlike TCP, it doesn't provide flow control or error-recovery functions – so it doesn't guarantee reliable data delivery. However, it's faster than TCP due to lower overhead.
Live streaming, online gaming, video calls, and DNS queries, where speed is prioritized over data integrity

Networking protocols

Many more networking protocols have been developed, and each one addresses a specific issue and fulfills a particular role.

Networking protocols include

File Transfer Protocol FTP makes it possible to transfer files between a local and a remote host, and to create and alter directories on the remote host.

FTP works on TCP ports 20 and 21. Port 20 is used for data transfers, and port 21 is used for control commands.
Trivial File Transfer Protocol TFTP is a simplified version of FTP used for file transfer, and booting network devices which don't have local storage. It uses the Universal Datagram Protocol, or UDP, port 69. Unlike FTP users, TFTP doesn't support authentication.
Post Office Protocol version 3, or POP POP3 is used to retrieve e-mail messages from a mailbox on a mail server. It uses port 110.

Once you've used POP3 to download e-mail, the messages are usually deleted from the mail server. As a result, POP3 isn't practical for people who access their e-mail from multiple computers.
Simple Mail Transfer Protocol, or SMTP SMTP is used alongside POP3 to send and receive e-mails. It uses a store-and-forward process, with e-mail messages automatically stored until the destination device is online. SMTP uses port 25.
Internet Message Access Protocol version 4, or IMAP4 Like POP3, IMAP4 is used to retrieve messages from a server. Unlike POP3, it enables users to access, search, and modify messages while they're still stored on a server. Users can also choose which messages to download. IMAP4 uses port 143.

Networking protocols include

Hypertext Transfer Protocol, or HTTP HTTP enables users to retrieve web pages from a server and interact with the pages using their web browsers. HTTP uses port 80.
Hypertext Transfer Protocol Secure, or HTTPS, and HTTPS is a secure version of HTTP that uses SSL to encrypt data. However, not all web browsers and servers support HTTPS. HTTPS uses port 443.
Server Message Block, or SMB SMB uses a client-server model to enable networked computers to communicate and to share resources such as files, printers, and serial ports. It's used mainly in Microsoft networks. SMB uses port 445.
Secure Shell, or SSH SSH enables you to log on to a remote computer or network device using a secure, encrypted connection. It uses port 22.
Secure Copy Protocol, or SCP SCP uses SSH to copy files safely between a local and remote host or between two remote hosts. Like SSH, it uses port 22.

SCP can also be implemented as a command-line utility that uses either SCP or SFTP to enable secure copying.
Telnet Telnet simulates a session on a remote host as if the PC you are using was a directly attached terminal. It translates keystrokes from your PC into keystrokes on the remote host. It then carries the output back and displays it on your computer.

Telnet uses port 23.

Networking protocols include

Secure Sockets Layer, or SSL SSL operates on port 443 to provide secure, encrypted data transfer. It uses digital certificates for authentication as well as public key data encryption. HTTPS can use SSL for secure web connections.
Transport Layer Security, or TLS Like SSL, TLS uses port 443. It protects sensitive communication from eavesdropping or tampering using a secure, encrypted, and authenticated channel. TLS was developed as a replacement for SSL and can be used for secure HTTPS connections.
Network Time Protocol, or NTP NTP is a protocol that synchronizes the clock times of network computers by exchanging time signals with a US Naval Observatory master clock. NTP is implemented via UDP over port 123.
Network News Transfer Protocol, or NNTP, NNTP is used to post and retrieve messages from the worldwide bulletin board system called USENET, which includes more than 14,000 forums – or newsgroups – devoted to specific topics. NNTP uses TCP port 119.
Network File System, or NFS NFS lets users access and share files distributed across a network as if they were stored locally. NFS uses port 2049.

DNS protocol

DNS resolves domain names into IP addresses, and vice-versa.

DNS protocol

To do this, it maintains a system of hierarchical databases, stored on separate servers on networks that connect to the Internet. The databases record IP addresses and the associated domain names.

LDAP, Protocol

The Lightweight Directory Access Protocol, or LDAP, defines how a client can access information, perform operations, and share directory data.

LDAP, Protocol

Generally, LDAP relies on DNS to enables clients to locate servers that host LDAP directories. The LDAP servers then enable clients to find the directory objects they're looking for.

Two similar protocols are

DHCP

Dynamic Host Configuration Protocol, or DHCP A DHCP server automatically assigns IP addresses and other configuration information to clients. To do this, it must be configured with at least one DHCPscope, which contains a range of available IP addresses and a subnet mask. It may also specify details such as a default gateway and DNS addresses.

Each assigned IP address is leased to a client for a defined period

BOOTP

the Bootstrap Protocol, or BOOTP BOOTP was a forerunner of DHCP designed for systems without local storage to obtain an IP address, since they couldn't store their address locally.

A BOOTP server assigns IP addresses from a pool of available addresses.

Zeroconf

Zero Configuration Networking, or Zeroconf, is a set of standards that enables automatic
configuration and IP address allocation on both Ethernet and wireless networks.

Zeroconf

Zeroconf networks can exist without central control or configuration services such as DHCP and DNS. Microsoft's APIPA is an example of a Zeroconf implementation.

ARP

The Address Resolution Protocol, or ARP, resolves hosts' IP addresses to the corresponding physical addresses in a local network.

ARP

When a computer in the network needs to resolve another computer's IP address, it first checks whether the corresponding physical address is available in its cached ARP table. A communication protocol that maps IP addresses to MAC addresses within a local network

ARP

If the required address hasn't been cached, the computer broadcasts an ARP message requesting the address. The target computer then responds with its physical address, which can be cached for future reference

RARP

The Reverse Address Resolution Protocol, or RARP, enables a device on a LAN to discover its IP address using a router's ARP table or cache.

RARP

A network administrator can use RARP to add a table to a LAN's router, mapping each node's physical address(MAC address) to its corresponding IP address.

RARP

When a node is added to the network, its RARP client program requests its IP address from the RARP server on the router.

RTP

The Real-Time Transport Protocol, or RTP, provides a standard packet format for transmitting audio and video content over IP networks.

RTP

It encapsulates streaming media content in time stamped packets with appropriate sequence numbers. Once they've been transmitted, the packets can then be correctly sequenced.

RTP

RTP uses a dynamic range of port numbers rather than a single, fixed port number. As a result, it can be difficult to configure a firewall to allow or block RTP traffic.

SIP

The Session Initiation Protocol, or SIP, is a signaling protocol for controlling multimedia communication sessions – for example, those involving voice or video calls over IP. It can initiate, modify, and terminate sessions.

ICMP,

The Internet Control Message Protocol, or ICMP, reports on the condition of a connection between two network devices.

ICMP,

For example, if data from a sender is arriving so fast that it's flooding the receiving node's buffers, the receiving node can use an ICMP source quench message to tell the sending node to slow down data transmission.

IGMP

The Internet Group Management Protocol, or IGMP, informs network systems which host currently belongs to which multicast group.

IGMP

For IGMP to work, routers have to support it, as well as multicast packet routing.

SNMP

The Simple Network Management Protocol, or SNMP, collects information from network devices for diagnostic and maintenance purposes.

SNMP

SNMP agent software is installed on network devices such as servers, routers, and printers. The agents then send information to an SNMP manager.

SNMP

The SNMP manager can notify an administrator of a problem, run a corrective program or script, store the information for later review, or query an agent about a specific network device.

recognise the importance of assigning ports to manage protocols

Ports

In a TCP/IP network, a port is a logical construct that serves as the endpoint of a connection within the OS of the end system. Each TCP/IP connection has an associated source and destination port specified in the header.
Think of a computer as a hotel:
The IP address is like the hotel address.
Ports are like room numbers—they direct incoming visitors (data) to the right place.

Ports

Each port is represented as a number from 0 to 65,535 - or 16 bits.

Ports

The Internet Assigned Numbers Authority, or IANA, separates port numbers into three blocks:

Ports

Well-known ports fall in the range from 0 to 1,023, and are pre-assigned for use by specific, widely used applications and services.
Registered ports fall in the range from 1,024 to 49,151. Software makers can register with IANA to use one of these ports, however, this isn't a requirement.
Dynamic ports are numbered from 49,152 to 65,535. They can't be registered with IANA, and are typically used for temporary or one-time connections.

Ports

An example of a well-known port is TCP port 80, which is assigned for use by Hypertext Transfer Protocol, or HTTP.

Ports

Well-known User Datagram Protocol, or UDP ports include port 53 - for use by DNS - and ports 67 and 68 - for use by DHCP

Ports

At communication endpoints in an IP network, sockets make it possible to deliver data packets to the appropriate services or application processes.

Ports

Each socket has an address that identifies a protocol, an IP address, and a port number. So each socket is bound to a particular port.

So how does the computer know to which application to forward the data? Through the use of ports.

Understanding Ports
Generally speaking, a computer has a single physical connection to the network. All data destined for a particular computer arrives through that connection. However, the data may be intended for different applications running on the computer. So how does the computer know to which application to forward the data? Through the use of ports.
Data transmitted over the Internet is accompanied by addressing information that identifies the computer and the port for which it is destined. The computer is identified by its 32-bit IP address, which IP uses to deliver data to the right computer on the network. Ports are identified by a 16-bit number, which TCP and UDP use to deliver the data to the right application.
In connection-based communication such as TCP, a server application binds a socket to a specific port number. This has the effect of registering the server with the system to receive all data destined for that port. A client can then rendezvous with the server at the server's port, as illustrated here:

ports

In datagram-based communication such as UDP, the datagram packet contains the port number of its destination and UDP routes the packet to the appropriate application, as illustrated in this figure:

An application provides TCP with a sequence of bytes, and TCP guarantees that it will deliver them to the remote computer accurately and in order, if they get there at all. TCP provides this not “ to a computer” but “between applications” — meaning TCP has another level of addressing that keeps track of which application the stream belongs to (i.e. a port number).

ports

acquire a working knowledge of the TCP/IP and OSI layer models

classify applications, devices and protocols in relation to the TCP/IP and OSI layer models

Models

Data communication over a network is a structured process and is governed by certain models.
The OSI model was developed by the International Organization for Standardization, or ISO. It consists of a hierarchy of seven layers, each representing a specific set of functions involved in transmitting data from one device to another over a network.
The model also references the network protocols typically used to support communication, positioning each protocol at the relevant layer based on its function.
https://www.youtube.com/watch?v=HEEnLZV2wGI an over view of osi model

Using a network reference model like the OSI model can have various benefits:

it divides the network communication process into smaller, simpler stages and functions
it encourages industry standardization by defining what functions occur at each network layer
it standardizes network components, making it possible for multiple vendors to create components that can communicate
it supports different types of network hardware and software, and
it makes applications easier to program because changes can be made at one layer without affecting all other layers
Because it provides a common understanding of network functions, the OSI model provides a basis for open system networks. These are networks that support multiple communication protocols from different vendors.

OSI

Information can come

from and go to each layer

Routers work at network layer

Switches work at layer 1 and 2,

because they deal with mac address

OSI

The OSI reference model divides the data communication process into seven tasks, which are grouped into different layers. Each layer is a collection of related functions, protocols, and devices that work at that layer. Every layer is
designed to link the layers above it. While a layer provides services to the layer above, it requests services from the layer below.

OSI

These are seven layers of the OSI model
The Physical layer is the lowest layer in the OSI model. It defines the physical media and specifications a network uses when transferring data. For example, it describes cables, connectors, or frequencies and modulation in wireless networks.
Network adapters and access points – APs – are some of the devices that operate at this layer.

The Physical layer

OSI

Protocols at the Physical layer receive fully formatted data frames from the Data Link layer and places them on the physical communications medium. The Physical layer determines the mode and medium of data transmission, which are factors that affect transmission speeds.

OSI

Protocols that function at this layer include Ethernet, Fast Ethernet, Asynchronous Transfer Mode – or ATM – Token Ring, and Fiber Distributed Data Interface – or FDDI.
The 802.11 wifi standards are also at the Physical layer. The physical layer is sometimes referred to as Layer 1 or L1.

Data Link

OSI

The Data Link layer – sometimes referred to as layer 2, or L2 – handles hardware addressing so that physically connected devices can be located.

OSI

The Data Link layer is responsible for transferring data packets between adjacent network nodes without any errors. After sending the packets, the Data Link layer waits for an acknowledgment from the receiving devices.

OSI

Network switches operate at the Data Link layer.

OSI

Protocols at this layer include the Point-to-Point Protocol, or PPP, and Serial Line Internet Protocol, or SLIP. They also include Synchronous Optical Networking – or SONET – and Frame Relay.

OSI

The Data Link layer is divided into two sub-layers:
The Logical Link Control – or LLC – sub-layer,
the Media Access Control – or MAC – sub-layer

OSI

The LLC is the aspect that talks to the systems operating system usually via device drivers. The LLC handles multiple network protocols and provides flow control., for instance Carrier Sense Multiple Access, or CSMA, and collision detection, or CD.
.The second job is called the MAC it adds the nics own MAC address to the frame

Network Layer

OSI

The Network layer specifies how to route data from hosts on one network to hosts on another network, based on the hosts' network addresses.
The Network layer is layer 3 or L3.

OSI

The Network layer contains several protocol families, categorized based on the functions they perform. These include protocols for
reliability
establishing and maintaining connections, and
routing

OSI

Protocols at the Network layer are IP, IGMP, and ICMP.

They also include ARP and RIP
IP is the abbreviation for Internet Protocol, IGMP is the abbreviation for Internet Group Management Protocol, ICMP is the abbreviation for Internet Control Message Protocol, ARP is the abbreviation for Address Resolution Protocol, and RIP is the abbreviation for Routing Information Protocol.

Transport Layer

OSI

End-to-end data transmissions occur on the Transport layer. This layer also implements mechanisms for ensuring reliable data transfer and data integrity, and for correcting transmission errors.
The Transport layer manages connections with the two layers adjacent to it – the Session layer above it and the Network layer below it.
Protocols on the Transport layer segment the data received from each session and pass it to the Network layer in the appropriate size and format.
The Transport layer is often referred to as Layer 4, or L4

OSI

The most common Transport layer protocols are the User Datagram Protocol – or UDP – and Transmission Control Protocol – or TCP

OSI-Transport layer protocols

OSI

The Session layer, layer 5 or L5, establishes connections between devices and applications, maintains the connection, and then terminates or re-establishes it when required.
Role of the Session Layer (Examples)
Logging into a website

Maintains your login session until you log out or timeout

Video calls (Zoom, Teams)

Keeps the connection stable and manages data flow

File transfer that resumes after a break

Synchronizes and resumes from the last checkpoint

Session Layer

OSI

The Session layer also specifies the procedures for synchronizing data transfer between two devices with different data transmission rates.
The TCP/UDP function of establishing sessions occurs at the Session layer. In addition, sockets operate at this layer.

OSI

Some protocols that operate at the Session layer are the Remote Authentication Dial-In User Service – or RADIUS – and Terminal Access Controller Access-Control System Plus, known as TACACS+.

OSI

Protocols at the Presentation layer, layer 6 or L6, ensure that data represented by one system can be interpreted by another system. For example, they convert special character data to ASCII.

OSI

Most programs contain data such as names, identification numbers, and passwords. These items may be represented as characters, integers, or floating numbers, and each device on a network may use a different code to represent the same data.
Moreover, standard data formats are used to enable devices with different representation techniques to communicate with each other. This translation is only an intermediary format, and will change at the lower layers.

Presentation Layer

OSI

The Presentation layer also adds data compression and security-related services like encryption and decryption.

Presentation-layer protocols for securing data communication include the Secure Socket Layer – or SSL, Transport Layer Security – or TLS – and Abstract Syntax Notation One – or ASN.1.

OSI

File formats in use at this layer include
Graphics Interchange Format – or GIF – which is a graphic interchange format primarily used on the Internet
Joint Photographic Experts Group – or JPEG – which is a compressed graphical file format that reduces image file size, and
Tagged Image File Format – or TIFF – which is a digital format for storing images that's popular with photographers and in the publishing industry

Application

OSI

The Application layer, which is the highest layer in the OSI model - Layer 7 or L7 - provides network services to end users, according to the applications they're using. It's the only layer that users interact with directly.
This layer includes protocols for tasks such as transferring files, sending e-mails, and saving data to network servers.

OSI

Examples of protocols that operate at the Application layer are HTTP, SNMP, SMTP, DNS, and FTP.

Other protocols at this layer include Gopher, NFS, NTP, X.400 directory services, Telnet, and FTAM.
SNMP is the abbreviation for Simple Network Management Protocol, SMTP for Simple Mail Transfer Protocol, DNS for domain name service, and FTP is the abbreviation for File Transfer Protocol. NFS is the abbreviation for Network File System, NTP for Network Time Protocol, and FTAM is the abbreviation for File Transfer and Access Management Protocol.

Data Flow

In a network, the flow of information from one device to another can be explained by the actions that occur at each layer of the OSI model.

Data Flow

When a host performs an action such as sending an e-mail to another host, the flow of data starts at the Application layer on the sending device. The data is transmitted downward through the different layers of the OSI stack until it reaches the Physical layer, which is the physical transmission medium.

Data Flow

From there, the data flows via a network connection and then back up a recipient device's network stack. The data ascends the various OSI layers until it arrives at the Application layer, where it can be accessed by the user of the recipient device.

Data Flow

Based on their functions, the layers in the OSI reference model can be classified as providing either
application support The application support block consists of the upper three layers – Application, Presentation, and Session. Connecting software programs to a network is the primary responsibility of this functional block.

Data Flow

network support The network support block is made up of the lower four layers – Transport, Network, Data Link, and Physical. Moving data on a network is the primary responsibility of this functional block.

The data encapsulation process

When a host transmits data across a network to another device, the data is wrapped – orencapsulated – in protocol and delivery information as it passes downward through each of the layers of the OSI model.

The data encapsulation process

At the receiving end, information that was added to the data is removed as it passes up the layers of the OSI stack. This process is called de-encapsulation.

The data encapsulation process

During the data encapsulation process, several steps occur at the transmitting device:
user information is converted to data The first step is to convert user input – or information at the Application layer – into a format that's suitable for transmission on a network.
Beside the Application layer of the OSI model, a data packet displays.

The data encapsulation process

data is converted to segments As the second step, the data stream is divided into smaller chunks, a Transport layer header is added, converting the data into segments, and a reliable connection is established between the transmitting and receiving hosts.
The Transport layer is highlighted, and the data becomes a segment at this layer.

The data encapsulation process

data segments are converted to packets or datagrams Once a connection between the transmitting and receiving hosts has been established, Network-layer protocols add a header to each data segment and then hand segments down to the Data Link layer.

Each segment is converted into one or more data packets, each with logical header information so that the packets can be sent to and reassembled at the required destination.
The Network layer is highlighted, and the data is a packet at this layer.

The data encapsulation process

datagrams or data packets are converted to frames for transmission, After data has been converted into packets, the Data Link layer receives the packets and prepares them for transmission.

Protocols on the Data Link layer add a frame and a MAC header to each data packet, to uniquely identify the host and hardware device to which the packet must be transmitted.
The Data Link layer is highlighted, and the data is a frame at this layer.

The data encapsulation process

frames are converted to bits During the last step in the encapsulation process, frames are converted into bits at the Physical layer. Digital encoding, a clocking scheme, or a signaling method is used to convert the data frames into a format that network devices can read and interpret.
The Physical layer is highlighted and data takes the form of bits at this layer.

TCP/IP

The TCP/IP model is a reference model that describes the process of network communication based on the TCP/IP suite of network protocols.

TCP/IP derives its name from Transmission Control Protocol – or TCP – and Internet Protocol – or IP. These are the two main protocols in the suite.

Because it provides the basic framework for Internet communications, TCP/IP is sometimes also referred to as the Internet Protocol Suite.

TCP/IP

The TCP/IP model was developed by the United States Department of Defense and consists of four layers. These are the Application, Transport, Internet, and Network Interface layers.

Each layer in the TCP/IP model performs a specific function.

Application layer The Application layer provides definition of protocols for file, mail, and hypertext transfer. It also handles the encoding of data, controls the sessions, and defines socket services and other utilities over TCP/IP.
Transport layer The Transport layer provides connection establishment and communication services. It also defines protocols for end-to-end transfer of data, along with error and flow controls. In the TCP/IP model, there are two transport layer protocols: TCP and UDP.
Internet layer The Internet layer provides addressing and routing services. It also controls congestion on the network. This layer involves transferring data from a source to a destination network when multiple networks are connected together.
Network Interface layerThe Network Interface layer provides services to send and receive data packets on the network. It defines protocols for moving data frames between adjacent nodes, and for accessing the medium by the devices. It defines the protocols for encoding and transmitting.

TCP/IP

The TCP/IP model encapsulation process is the same as for the OSI model. The application interfaces with the Application layer, then the data is passed down to the Transport and Internet layers, and then forwarded to the Physical layer for transmission.

TCP/IP

When the destination device receives the data, the same process occurs across the destination device's TCP/IP layers – but in reverse.