For the TCP/IP Model (implemented model) see [[TCP-IP Model]]. The framework for how all networked devices will send, receive, and interpret data. 7 layers (like the best burrito ever made). From 7 going down. 7: Application - This is where protocols and rules live that determine how users should interact with sent or received data. 6: Presentation - standardization takes place. Acts as a translator for data to and from the application layer (layer 7). Additionally, security features such as data encryption such as HTTPS, occur at this layer. 5: Session - once data has been translated/formatted from the presentation layer, the session layer will create and maintain the connection to the other computer for which data is intended. 4: Transport - uses Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) protocols to transmit data across a network. Enables end-to-end communication between running applications on different hosts. 3: Network - the routing portion where the most optimal path for sending data chunks is chosen. Open Shortest Path First (OSPF) and Routing Information Protocol (RIP). Devices operating at this level are capable of delivering packets using IP addresses. 2: [[Data Link]] - physical addressing of the transmission. This is also where FRAMES exist. Frames do not have an IP address, just data. Frames are encapsulated when transmitted and the encapsulation is stripped, it is just the frame by itself. 1: Physical | Layer | Name | Function | Protocol & Standards | | ----- | ------------ | ------------------------------------------------------ | ----------------------------------------- | | 7 | Application | Provides services and interfaces to applications. | HTTP,FTP,DNS,POP3,SMTP,IMAP | | 6 | Presentation | Data encoding, encryption, encapsulation. | Unicode, MIME,JPEG,PNG,MPEG | | 5 | Session | Establishing, maintaining, and synchronizing sessions. | NFS,RPC | | 4 | Transport | End-to-end communication and data segmentation. | UDP,TCP | | 3 | Network | Logical addressing and routing between networks. | IP,ICMP,IPsec | | 2 | Data-link | Reliable data transfer between adjacent nodes. | Ethernet (802.3), WiFi (802.11) | | 1 | Physical | Physical data transmission. | Electrical, optical, and wireless signals | NOTE: in the data link layer (layer 2), when a piece of data does not have an IP address it is called a Frame. When it does have an IP address is it called a packet.