OSI v/s TCP/IP MODEL8.1 # OSI MODEL : 7 LAYERS EXPLAINED IN COMPUTER NETWORK
Network means Interconnect and in information technology, a network is a series of points or nodes interconnected by communication path.
Types of Network: In the world of computers, networking is the practice of linking two or more computing device together for the purpose of sharing data. Networks are built with a mix of computer hardware and computer software.
# OSI REFEENCE MODEL is International standard organization (ISO) established a committee in 1977 to develop architecture for computer communication. Open System Interconnection (OSI) reference model is the result of this effort. In 1984, the OSI reference model was approved as an International standard for communications architecture. Term “open” denotes the ability to connect any two systems which confirm to the reference model and associate standards.
Types of OSI Reference Model: There are seven types and its divide into two parts.1) LowerLayer : First four layers are known as Lower layer, include as Physical, Data link, Network and Transport layers. These layers do work for network.
2) Upper Layer : Last three layers is known as Upper layer, include as Session, Presentation and Application layers. These layers do work for application.
Task Performance :
I) Physical Layer : It is sent the packets to the networking hardware and Covers all – mechanical, electrical, functional and procedural – aspects for physical communication. Devices: Repeater, Hub and Media convertor. Inother words, its able to work for access to media.
o Logical Link Control (LLC): Provide the services to the network layer below it.
o Media Access Control (MAC): It is necessary to have rules for managing the medium to avoid conflicts. Devices: Bridges and Switches.
Protocols: ARP, NDP, Tunnels (L2TP), PPP, MAC (Ethernet, DSL, ISDN, FDDI).
Protocols: IP (IPV4, IPV6) PDU, TCP/IP suit, Internet protocol, ICMP, ARP, IGMP, IPsec.
Protocols: TCP, UDP, DCCP, DSTP, RSVP, SPX, CRS, Motto and more. Inother words, its able to work for end-to-end communication.
1. Simplex duplex 2. Half-duplex 3. Full duplex
Offering: X- Window, NFS, Remote procedure call and Structure Query Language (SQL), Session establishment, Session control, Maintenance and Termination.
Format offering: Rich data format, Musical instrument, Digital interface, Quick time movies, MPEG files. Inother words, its able to work for data formatting.
Protocols: BGP, DHCP, DNS, FTP, HTTP, IMAP, LDAP, MGCP, NNTP, NTP, POP, RIP, ONCRPC, RTP-RTSP, SIP, SMTP, SNMP, SSH, Telnet, TLS/SSL, XMP and more
Whether a designed to be a humorous extension or a secret technician code, layers 8, 9, and 10 are not officially part of the OSI model. They refer to the non-technical aspects of computer networking that often interfere with the smooth design and operation of the network.
Layer 8 is usually considered the “office politics” layer. In most organizations, there is at least one group who is favored, at least temporarily, by management and receives “special” treatment. When it comes to networking, this may mean that this group always has the latest and/or fastest equipment and highest speed network links.
Layer 9 is generally referred to as the “blinders” layer. This layer applies to organizational managers who have
already decided, usually with little or no current information, to dictate a previously successful network plan.
They may say things such as:
“It worked in my last company, so we will use it here.”
“Everybody says this is the right solution.”
“I read in an airline magazine that this was the best way to do it so that is what we will do.”
What these managers seem to forget is that they are paying a highly qualified staff to provide them with useful information. These managers bypass planning in order to make a quick decision.
Layer 10, the “user” layer, is in every organization. But users are much more than a layer. While they are one of the reasons the network exists, users can also be a big part of the need for troubleshooting. This is especially true when the users have computers at home and have decided to “help” the network administrator or manager by making changes to the network without consulting the network staff. Equally challenging is the user who “didn’t do anything” when the network segment in his/her immediate vicinity suddenly stopped working. In these cases, the layer 10 identification coincides with layer 10 troubles (and the “ID10T” label some technicians have used).
8.2 # NETWORING LAYER FUNCTION
a) Grouping Layer: -
- Application : File, Printer, Message, Database and application services
- Presentation : Data translation
- Session : Dialog control (Maintains tracks and session between application)
b) Layer 3 broadcasts: These are sent to all nodes on the network.
c) Unicast: These are sent to a single destination host.
d) Multicast: These are packet sent from a single source and transmitted to many devices on different networks.
8.3 # TCP/IP MODEL EXPLAINED IN COMPUTER NETWORK
TCP have a no limit and it is responsible for data delivery once that IP address has been found. The Transmission Control Protocol (TCP) is a transport protocol that is used on top of IP to ensure reliable transmission of packets. TCP provides communication between an application program and the Internet Protocol.It is the popular model in the history of Networking and supported by every computer Operating system. It is maintained in an open forum and TCP/IP specifies how data should be packaged, transmitted and routed in their end to end data communication. There are four layers as
1) Network access layer 2) Internet layer3) Transport or Host to Host layer 4) Application or Process layer
• Application Layer: This is the top layer in the TCP/IP model. It includes processes that use the Transport Layer Protocol to transmit the data to their destination. There are different Application Layer Protocols such as HTTP, FTP, SMTP, SNMP protocols, etc.
• Transport Layer: It receives the data from the Application Layer which is above the Transport Layer. It acts as a backbone between the host’s system connected with each other and it mainly concerns about the transmission of data. TCP and UDP are mainly used as Transport Layer protocols.
• Network or Internet Layer: This layer sends the packets across the network. Packets mainly contain source & destination IP addresses and actual data to be transmitted.
• Network Interface Layer: It is the lowest layer of the TCP/IP model. It transfers the packets between different hosts. It includes encapsulation of IP packets into frames, mapping IP addresses to physical hardware devices, etc.
8.4 # UDP HEADER FORMAT EXPLAINED IN COMPUTER NETWORK
We can say that it is limitless but TCP and UDP are foundational pillars of the internet, enabling different types of data transmission from a network source to the destination. TCP is more reliable, while UDP prioritizes speed and efficiency. UDP does not require the source and destination to establish a three-way handshake before transmission takes place. Additionally, there is no need for an end-to-end connection.And also UDP benefits applications that need to receive data quickly even if accuracy suffers. This is why real-time applications like audio and video streaming will often use UDP.
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