Chapter 6: Telecommunications and Network Security

• Risk and complexity has a direct relationship when it come to technology. As the complexity of technology increases so does risk. Risks are in the form of attackers who are becoming more trained, organized, and very focused. 

Telecommunications:

• Telecommunication is the electrical transmission of data among systems, whether through analog, digital, or wireless transmission types (Harris, 517).
• Telecommunication refers to telephone systems, service providers, and carrier services.
• Telecommunications are regulated by the government and international organizations. 
• The main standards organizations are the International Telecommunication Union (ITU) and the International Standards Organization (ISO).
• ISO is a worldwide federation that works to provide international standards.

Open Systems Interconnection Reference Model:

• OSI model, is an abstract framework most operating systems and protocols adhere to. 
• OSI model was introduced in 1984 when the basics of the Internet had already been developed and implemented. 
• OSI reference model provided important guidelines used by vendors, engineers, developers etc.
• Goal is to help others develop products that will work within an open network architecture. 

Protocol:

• A network protocol is a standard set of rules that determines how systems will communicate across networks and if two different systems use the same protocol, it can communicate and understand each other despite their differences. 
• Open network architecture is not owned by any venders, it's not proprietary, and it can integrate various technologies and vendor implementations of those technologies. 
• Encapsulation:
• the communication between computers through logical channels
• each protocol at a specific OSI layer on one computer communicates with a corresponding protocol operating at the same OSI layer on another computer. 

• How encapsulation works:
• Figure 6-2 from CISSP All-in-One Exam Guide book illustrates how encapsulation works.
• First a message is constructed within a program on one computer and then passed down through the network protocol's stack. 
• Information is added to the message at each layer by a protocol and the message grows in size as it moved through each protocol layer. 
• When the message arrives at the destination computer, encapsulation is reversed by taking the packet apart through the same steps used by the source computer that encapsulated it. 
• Therefore, at the data link layer, only the information pertaining to the data link layer is extracted, then the message is sent to the next layer. At the network layer, only the network layer data are stripped and processed, then the packet is passed on to the next layer and so on.