Chapter 1. introduction to tcpip networking
- 2. Why OSI 1. Connecting two different vendor device 2. Ease of troubleshooting Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer
- 3. Overview It is a 7 layer model developed by ISO at 1984. Each layer defines specific function. Note that every communication no need to be go through all the layers. It can skip some layers if needed - ** Will be discussed later Each layer is a package of protocol
- 4. Layers Layer 7 - Application Layer Layer 6 - Presentation Layer Layer 5 - Session Layer Layer 4 - Transport Layer Layer 3 - Network Layer Layer 2 - Data Link Layer Layer 1 - Physical Layer
- 5. Physical Layer All your physical components of the network connectivity comes under this layer. Ex. Ethernet Cable, HUB, RJ45, Fiber Cables.
- 6. Data Link Layer Switching technology lies here in DLL Layer MAC addresses are used for communication MAC address header will be attached in this layer. PDU : Frame Ex. Switch
- 7. Network Layer IP header will be encapsulated to the data in this layer. Routers are of Network Layer devices. Functions : Logical Addressing : It helps in assigning an IP address to a device Routing : Helps in providing reachability to a destination device via routers Path determination : Helps in selecting the best path when we have multiple route to reach same destination. Example : Router PDU : Packet
- 8. Transport Layer This layer decides how to transfer a data. It checks the reliability of the data sent. Functions : Segmentation : Data received by session is segmented and each segment will use sequence number to re- arrange the segments by the receiver. Flow Control : To slow down or faster the data transmission between two devices Error Control : The segment uses Checksum to check the error in the data received. TCP : Transmission Control Protocol - Its a connection oriented protocol each and every packet sent, the source should receive an acknowledgement if not received then source will retransmit the packet. UDP : User Datagram Protocol - Its a connectionless protocol, no acknowledgement will be there for the packet sent. PDU : Segment
- 9. Session Layer Helps in setting up and maintaining a connections. It uses API’s Functions : Authentication : Used by the server to check the user’s username and password Authorization : Used by the server to check if the user has the access to the data he is trying to access or not. PDU : Data
- 10. Presentation Layer How a data is going to be presented to the user. It can be a image, video or audio file. Functions : Translation : converts or translates date to machine language which comes from Application layer Compression : It does Data Compression so that data transmission can be faster and to reduce size of data Encryption/Decryption : It does encryption so that the data sent is secured. PDU : Data
- 11. Application Layer If you have any software in the computer that dont want to communicate to the internet then it wont use this layer ex. VLC player, but the web browsers need to communicate to the internet so behind all the web browsers we have a layer called application layer so that it can talk with the internet . Application Layer Protocol example : IP, FTP, SMPT, Telnet, SNMP etc., PDU : Data Internet Chrome application Application Layer