The OSI Layers and Protocol Stacks

There are so many functions that must be performed to interoperate systems, a structure is required to organize the functions so that separate issues can be treated separately.

We'll explore the most commonly-used structure, the ISO Open Systems Interconnection 7-Layer Reference Model.

You'll learn what a layer is, the purpose of each layer, examples of protocols like TCP and IP used to implement layers, and gain a true understanding of how a protocol stack works for applications like web surfing and VoIP.

Telecom Module 12

Detailed Outline

12 OSI Layers and Protocol Stacks

12.1 Protocols and Standards

..... 12.1.1 Functions To Be Performed

..... 12.1.2 Monolithic vsStructured Protocols

..... 12.1.3 Open Systems and Standards

12.2 ISO OSI Reference Model

..... 12.2.1 Layers

..... 12.2.2 Separability of the Layers

..... 12.2.3 Protocol Stacks

12.3 The OSI 7-Layer Model

12.4 Physical Layer: 802.3, DSL, DOCSIS, Wireless

12.5 Data Link Layer: 802 MAC

..... 12.5.1 LANs, Frames and Layer 2 Switches

..... 12.5.2 MAC Frames and MAC Addresses

..... 12.5.3 Other Data Link Protocols

12.6 Network Layer: IP and MPLS

..... 12.6.1 Packet-Switched Networks

..... 12.6.2 Routing Table Updates

..... 12.6.3 MPLS

12.7 Transport Layer: TCP and UDP

..... 12.7.1 Reliability

..... 12.7.2 Port Numbers

12.8 Session Layer: POP, SIP, HTTP

..... 12.8.1 Password Authentication

..... 12.8.2 Authentication Servers

..... 12.8.3 Password Caching

..... 12.8.4 Cookies

..... 12.8.5 Client-Server Sessions

..... 12.8.6 Peer-Peer Sessions

12.9 Presentation Layer: ASCII, Encryption, Codecs

12.9.1 Character Coding

..... 12.9.2 E-Mail Coding

..... 12.9.3 Codecs

..... 12.9.4 Data Compression

..... 12.9.5 Symmetric Encryption: Private Key

..... 12.9.6 Asymmetric Encryption: Public Key Encryption and Digital Signatures

..... 12.9.7 Example of Separability of Layers

..... 12.9.8 Example of Peer Protocol

12.10 Application Layer: SMTP, HTML, English …

..... 12.10.1 Email

..... 12.10.2 More Application Layer Examples

12.11 Protocol Stacks

..... 12.11.1 Example: Web Surfing

..... 12.11.2 Voice over IP

12.12 Protocol Stack in Operation: Ukrainian Dolls

..... 12.12.1 Communications Flow

..... 12.12.2 Segmentation at Each Layer

..... 12.12.3 Nested Headers

12.13 Standards Organizations

..... 12.13.1 ISO

..... 12.13.2 DOD and IETF

..... 12.13.3 ITU and Bellcore

..... 12.13.4 TIA and IEEE

..... 12.13.5 3GPP

..... 12.13.6 ANSI