OSI reference model
- 1. OSI REFERENCE MODEL 1 ISHAN UDYOGA
- 2. Introduction 2 ļµ Open Systems Interconnection Basic Reference Model (OSI Reference Model or OSI Model) is an abstract description for layered communications and computer network protocol design. It was developed as part of the Open Systems Interconnection (OSI) initiative. In its most basic form, it divides network architecture into seven layers which, from top to bottom, are the Application, Presentation, Session, Transport, Network, Data-Link, and Physical Layers. It is therefore often referred to as the OSI Seven Layer Model.
- 3. OSI Model's 7 Layers Application 3 Presentation Session Transport Network Data Link Physical TCP/IP Application Host to Host Internet Internet Access Data Segments Packets Frames Bits
- 4. OSI Model's 7 Layers 4 User 1 User 2 Application Presentation Session Transport Network Data Link Physical Application Presentation Session Transport Network Data Link Physical Higher Layer Middle Layer Lower Layer Physical Medium Data
- 5. 5 Application Layer User 1 FTAM X.500 X.400 Data Application Layer ļµ The application layer is responsible for providing services to the user. ļµ Concerned: ļµ Network virtual terminal (Software) ļµ File transfer, access and management ļµ Mail services ļµ Directory services (access to distributed database sources for global information about various objects and services) FTAM X.500 X.400 Data User 2 To Presentation Layer From Presentation Layer
- 6. 6 Presentation Layer User 1 User 2 From Application Layer ASCII Binary JPEG Data To Session Layer ļµ The presentation layer is responsible for translation, compression and encryption ļµ Concerned: ļµ Translation (interoperability between different encoding system) ļµ Encryption (Privacy schemes) ļµ Compression (data compression) To Application Layer ASCII Binary JPEG Data From Session Layer presentation Layer
- 7. 7 Session Layer User 1 User 2 From Presentation Layer Session Layer Communicate with user 2 Communicate with user 1 Data To Transport Layer To Presentation Layer Data From Transport Layer ļµ The session layer is responsible for dialog control and synchronization ļµ Concerned: ļµ Dialog Control (Half Duplex/Full duplex) ļµ Synchronization (Synchronization points, process inline within same page)
- 8. 8 Transport Layer User 1 User 2 From Session Layer Data To Network Layer To Session Layer Data From Network Layer TCP/UDP Transport Layer ļµ The transport layer is responsible for the delivery of a message from one process to another ļµ Concerned: ļµ Service-point addressing (Port address) ļµ Segmentation and reassembly (Sequence number) ļµ Connection control (Connectionless or connection oriented) ļµ Flow control (end to end) TCP/UDP
- 9. 9 Network Layer User 1 User 2 From Transport Layer Data To Data Link Layer To Transport Layer Data From Data Link Layer IP/IPX Network Layer IP/IPX ļµ The network layer is responsible for the delivery of individual packets from the source host to the destination host. ļµ Concerned: ļµ Logical addressing (IP Address) ļµ Routing (Source to destination transmission between networks)
- 10. 10 Data Link Layer User 1 User 2 From Network Layer Data To Physical Layer To Network Layer Data From Physical Layer STP/VTP/CDP Data Link Layer STP/VTP/CDP ļµ Data link layer is responsible for moving frames from one hop (Node) to the next. ļµ Concerned: ļµ Framing (stream of bits into manageable data units) ļµ Physical addressing (MAC Address) ļµ Flow Control (mechanism for overwhelming the receiver) ļµ Error Control (trailer, retransmission) ļµ Access Control (defining master device in the same link)
- 11. 11 Physical Layer User 1 User 2 From Data Link Layer 10110110011101011 To Data Link Layer 10110110011101011 Bits/Bytes Physical Layer Bits/Bytes ļµ One of the major function of the physical layer is to move data using electromagnetic signals across a transmission medium. ļµ Its responsible for movements of individual bits from one hop (Node) to next. ļµ Concerned: ļµ Physical characteristics of interface and medium (Transmission medium) ļµ Data rate (duration of a bit, which is how long it last) Transmission Medium
- 12. Data, Protocol & Activities 12 OSI Layers TCP/IP Suit Activities Application Telnet, FTP, SMTP, HTTP, DNS, SNMP, Specific address etcā¦ Presentation Session Transport SCTP, TCP, UDP, Sockets and Ports address Network IP, ARP/RARP, ICMP, IGMP, Logical address Data Link IEEE 802 Standards, TR, FDDI, PPP, Physical address Application Presentation Session Transport Network Data Link To allow access to network resources To Translate, encrypt, and compress data To establish, manage, and terminate session To Provide reliable process-to-process Message delivery and error recovery To move packets from source to destination; to provide internetworking To organize bits into frames; to provide Hop-to-hop delivery Physical Medium, Coax, Fiber, 10base, Wireless Physical To Transmit bits over a medium; to provide Mechanical and electrical specifications
- 13. 13 Thanks !