What each common protocol does, the four-layer TCP/IP model, how packet switching moves data across the internet, PANs, and how a network is kept secure.
What you will learn
- Match protocols to their jobs
- Put protocols into TCP/IP layers
- Describe packet switching
- Put packets back in order
- Choose methods to keep a network secure
Protocols
A protocol is a set of rules for sending and receiving data.
Standards let equipment from different makers work together.
| Protocol | Job | Layer |
|---|---|---|
| HTTP / HTTPS | web pages (HTTPS encrypted) | Application |
| FTP | transferring files | Application |
| SMTP | sending email to and between mail servers | Application |
| IMAP / POP | reading email (IMAP keeps it on the server; POP downloads it) | Application |
| TCP / UDP | splitting into packets, ordering and checking (UDP: faster, no resending) | Transport |
| IP | addressing and routing packets | Internet |
| Ethernet / Wi-Fi | sending frames on the local network | Link |
Layers split the job up: each layer has its own protocols and only talks to the layers next to it, so one layer can change without the others.
TCP checks that every packet arrives and has lost ones sent again. UDP does not wait to resend lost packets, so it is faster: a live video call would rather skip a lost moment than pause for it.
The rest of this lesson and its 13 practice questions are locked.
In this lesson
- Protocols
- Packet switching
- Families of protocols, PANs and security
- Try it: Which protocol?
13 practice questions, marked as you go; about 25 minutes in all.
Key terms
Protocol, Standards, Layers, Ethernet, Wi-Fi, Family, WLAN, PAN, Access control, Physical security
In this unit: Networks and protocols
LANs, WANs and PANs, network hardware, star, mesh and bus topologies, the internet and DNS, IP and MAC addresses, protocols and layers, network security, and transfer time calculations.
- Networks and network hardware
- Topologies and the internet
- Protocols, layers and packets
- Network calculations
- Extended answers