OSI Model
The Open Systems Interconnection model (OSI model) was a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a way of sub-dividing a communications system into smaller parts called layers. Similar communication functions are grouped into logical layers. A layer provides services to its upper layer while receiving services from the layer below. On each layer, an instance provides service to the instances at the layer above and requests service from the layer below.[1]
For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path. Two instances at one layer are connected by a horizontal connection on that layer.[1]
Overview
| OSI Model | Examples |
|---|---|
| Application Layer | HTTP, FTP, SMTP, LDAP, DHCP, DNS, SSH, |
| Presentation Layer | TLS/SSL, MIME, |
| Session Layer | NetBIOS, |
| Transport Layer | TCP, UDP, |
| Network Layer | IP, IPsec, ICMP, |
| Data Link Layer | Ethernet, Token Ring, FDDI, Wi-Fi, |
| Physical Layer | UMTS, |