O'Reilly logo

CCIE Security v4.0 Quick Reference, Third Edition by Umesh Lakshman, Lancy Lobo

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Chapter 1. Infrastructure, Connectivity, Communications, and Network Security

Networking Basics

The International Standards Organization (ISO) developed the Open Systems Interconnection (OSI) model to enable the delineation of various functions performed by devices in the network and applications. The OSI model is a conceptual model composed of seven layers, each specifying a particular network function. Data being transferred from a software application on one computer system to another must pass through the OSI layers. For example, if a software application in System A has information to transmit to a software application in System B, the application program in System A passes its data to the application layer (Layer 7) of System A. The application ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required