Practical Analysis of OSI vs TCP/IP Models Through Network Simulation

Welcome!

You have joined NetSecureX Solutions as a Junior Network Analyst, where users are experiencing slow internet speeds and connectivity problems. Your responsibility is to examine how data moves across the network using tools like Wireshark and commands such as ping, arp, and curl. By tracking packets through the OSI and TCP/IP layers and analyzing the behavior of TCP and UDP protocols, you work to identify network issues and enhance overall communication performance.

Topic : Core Internet Technologies

1) TCP/IP And OSI Model.

2) Ports and common network protocols.

Practical Analyze TCP vs UDP Protocol Behavior Trace Data Flow Across Network Layers Practically Perform real commands to relate theory with practice

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• The Network Interface Card (NIC) converts digital data into electrical or wireless signals.

• The physical wire (Ethernet cable) carries these signals between devices for communication.

OSI Layer

Filter:

arp

Perform:

Filter:

icmp

Observe:

• Echo Request

• Echo Reply

• TTL exceeded (as in your screenshot)

Conclusion:

• ICMP is used for network diagnostics

• TTL shows packet lifetime → routers decrement it

Perform:

Filter:

tcp

Perform:

Open browser → visit any website

Observe:

• SYN

• SYN-ACK

• ACK

• FIN, ACK

Special Filter (screenshot):

tcp.flags.syn == 1

Conclusion:

• TCP uses 3-way handshake

• Provides reliable communication

Filter:

tcp.stream eq X

(Select a packet → right-click → Follow → TCP Stream)

Observe:

• Continuous session between client & server

• Session start & end (SYN → FIN)

Conclusion:

• Session layer manages connection lifecycle

Filter:

Tls or ssl

Perform:

Observe:

• TLSv1.2 / TLSv1.3 packets

• Encrypted Application Data (as in your screenshot)

Conclusion:

• Handles encryption/decryption

• Data is unreadable (secured)

Filter:

http

Perform:

Observe (image):

• GET request

• HTTP/1.1 200 OK

• Website data

Since we have already explained the OSI model using Wireshark, most of the packet-level details are covered there.

The TCP/IP model can be understood by mapping its layers to OSI:

• Application → OSI Application, Presentation, Session

• Transport → OSI Transport

• Internet → OSI Network

• Network Access → OSI Data Link + Physical

So, instead of repeating the same analysis, we will refer to the OSI Wireshark practical and use it to understand how TCP/IP layers work in real network communication.

Topic : Network Routing & Communication

1) Routing Process - ARP DHCP NAT

2) Routing Protocols – BGP RIP OSPF