Networking Concepts Review - CCIE Routing and Switching Exam Certification Guide - page 47

Foundation Summary

The Foundation Summary is a condensed collection of material that provides a convenient
review of key concepts in this chapter. If you are already comfortable with the topics in this
chapter, this summary will help you recall a few details. If you just read the Foundation Topics
section, this review should help solidify some key facts. If you are doing your final preparation
before the exam, these materials are a convenient way to review the day before the exam.

OSI Reference Model Table 2-7

Layer
Number

OSI Layer
Name Description

7 Application Provides the user or operating system access to the network services.

6 Presentation Data representation, compression, encryption, voice coding.

5 Session Establishes, manages, and terminates communication connections called

sessions.

4 Transport Provides reliable, transparent transport of data segments from upper layers. It

provides end-to-end error checking and recovery, multiplexing, virtual circuit
management, and flow control.

3 Network Concerned with routing of packets and methods to determine paths to a

destination.

2 Data-link Reliable transport of data frames across a physical link. Data-link

specifications include the following: sequencing of frames, flow control,
synchronization, error notification, network topology, and physical
addressing.

1 Physical Bits and interfaces. Concerned with the electrical, mechanical, functional, and

procedural specifications for physical links.

Decimal, Binary, and Hexadecimal Numbers Table 2-8

Decimal
Value Hexadecimal Binary

0 0 0000

1 1 0001

2 2 0010

3 3 0011

4 4 0100

5 5 0101

continues