Protocols and Devices Per Layer

---

📘 Overview

This page maps the OSI layers and TCP/IP layers to the protocols and networking devices that operate at each level.

Think of it as:
“What works where?” — Which devices and protocols belong to each layer of the networking stack.

---

🔁 OSI Model: Protocols & Devices by Layer

OSI Layer	Protocols	Devices
7 - Application	HTTP, FTP, SMTP, DNS, SNMP	Web Browsers, Email Clients, SNMP Tools
6 - Presentation	SSL/TLS, JPEG, MPEG, ASCII, Unicode	Encryption Modules, Codecs
5 - Session	NetBIOS, RPC, SMB	Session Managers, Software APIs
4 - Transport	TCP, UDP	Firewall (Port Filtering), Load Balancers
3 - Network	IP, ICMP, IGMP, ARP	Routers, Layer 3 Switches
2 - Data Link	Ethernet, PPP, VLAN, 802.1Q	Switches, NICs, Bridges
1 - Physical	Ethernet (IEEE 802.3), RS-232, DSL, Wi-Fi	Hubs, Cables, Repeaters, Modems, Fiber Media

---

🌐 TCP/IP Model: Protocols & Devices by Layer

TCP/IP Layer	Protocols	Devices
Application	HTTP, HTTPS, FTP, DNS, SMTP, SNMP	Browsers, Email Apps, CLI Tools
Transport	TCP, UDP	Firewalls, Load Balancers
Internet	IP, ICMP, ARP, IGMP	Routers, Layer 3 Switches
Network Interface	Ethernet, Wi-Fi, MAC	NICs, Switches, Hubs, Access Points

---

🧠 Real-Life Protocol & Device Pairings

Task	Protocol	Device
Browse the web	HTTP / HTTPS	Web Browser, Firewall
Transfer files	FTP / SFTP	Server, Client
Send an email	SMTP, IMAP, POP3	Mail Client
Assign IP address	DHCP	DHCP Server, Router
Resolve domain name	DNS	DNS Resolver, Router
Route packets	IP	Router
Connect LAN devices	Ethernet	Switch
Connect networks	IP	Router
Transmit bits	None (just electrical/light signal)	NIC, Cable, Hub

---

🔁 Related Pages

• OSI Model Overview
• TCP/IP Model Overview
• Encapsulation Explained
• MAC Address
• IP Address
• Router
• Switch
• Firewall
• Wireshark Lab Pages

---

Return to: Chapter 2