Navigating the Cyber Seas: My Journey Through the TCP/IP Protocol Suite
Greetings cyber people! Today marks another day in my journey towards becoming a proficient expert in the field. And today, I am excited to share with you one of the important boxes I’ve ticked off my list — my continued learning in “NETWORKING”.
In this blog, we will delve into the world of network models — specifically, the OSI(Open System Interconnection) model and its relevance to the real world. As we all know, the OSI model is a widely used model for network layers. However, debates about its relevance to the real world have surfaced. Hence, in studying for the CCNA, I learned about the hybrid of the OSI model and the RFC (Request For Comment) model, which is an older model. The hybrid of these two models is the TCP/IP protocol suite, which we will explore throughout my journey.
Unlike the OSI model, the TCP/IP model is more realistic and consists of five layers of networks, which are the physical, data link, network, transport, and application layers. Let’s start from the bottom, with the physical layer.
The physical layer defines how bits move from one device to another, detailing how cables, connectors, and network interface cards work, and how bits are sent and received. Data travels in zeros and ones, passing through fiber cables as light.
Next is the data link layer, which encapsulates a packet in a frame. A frame contains a header and a trailer that enable devices to communicate. A header commonly contains a source and destination MAC address, while a trailer contains the Frame Check Sequence field, which is used to detect transmission errors. The data link layer has two sublayers — the Logical Link Control used for flow control and error detection, and the Media Access Control used for hardware addressing and controlling access methods.
The network layer defines device addressing, routing, and path determination, with logical addressing identifying a host on a network using its IP address. A router, which is a layer 3 device, will route packets from one interface to another.
The transport layer segments big chunks of data received from upper layer protocols, establishes and terminates connections between two computers, and is used for flow control and data recovery.
Finally, the application layer is the closest to the user, enabling network applications to communicate with other network applications. In the TCP/IP model, the following OSI model stack falls under this layer — the session layer, which defines how to establish and terminate a session between two systems, and the presentation layer, which defines data formats with compression and encryption.
To further understand these concepts, I did some packet tracer labs to see for myself, and I highly recommend trying it out on Cisco Net Academy.
As I move forward in my cybersecurity journey, I must understand all these concepts and protocols to become grounded in the technical field. Understanding these concepts will also make me a good application developer, as David Bombal mentioned in his course on CCNA networking. He even emphasized how many nightmares are caused for network engineers today because of badly written applications by developers.
I hope you enjoyed reading this blog and learned something new. Let’s go through this journey together, and stay tuned for more exciting updates. Till we meet again!
