Definition

Open Systems Interconnection Model Remember the layers: *P*eople *D*o *N*eed *T*o *S*ee *P*amela *A*nderson

Layer description

Examples

Encapsulation

The TCP/IP model uses terms such as segment, packet, and frame to refer to various layers and their respective , OSI uses a more generic term: protocol data unit (PDU).

Benefits

• Less complex
  • Compared to not using a layered model, network models break the concepts into smaller parts. Standard interfaces: The standard interface definitions etween each layer allow multiple vendors to create products that fill a particular role, with all the benefits of open competition.
• Easier to lear
  • Humans can more easily discuss and learn about the many details of a protocol specification.
• Easier to develop
  • Reduced complexity allows easier program changes and faster product development.
• Multivendor interoperability
  • Creating products to meet the same networking standards means that computers and networking gear from multiple vendors can work in the same network.
• Modular engineering
  • One vendor can write software that implements higher layers—for example, a web browser—and another vendor can write software that implements the lower layers—for example, Microsoft’s built-in TCP/IP software in its OSs.