Seven layers is a lot to carry
Engineers who built the internet did not wait for a seven-layer plan. They built a smaller one that worked, and the whole world now uses it.
It has four layers. Today you learn them, and you match them to the seven you already know.
Key words
| Word | What it means |
|---|---|
| TCP/IP model | the four-layer model the internet is built on |
| Application layer | the layer for services such as web, email and names |
| Transport layer | the layer that numbers parts and delivers them to a program |
| Internet layer | the layer that names devices across networks and picks routes |
| Network layer | the layer for the local link: frames and signals |
| Protocol | a set of rules computers follow to talk to each other |
| Header | extra facts a layer adds to the front of the data |
| Network | devices joined so they can share things |
| OSI model | the seven-layer model |
| IP address | a number that names a device on a network |
| MAC address | a number built into a network card |
| Ethernet | the usual wired way to join devices in a building |
| DNS | domain name system: it turns a name into an IP address |
| OSPF | a protocol for sharing a map of routes to find the best path |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can name the four TCP/IP layers and place a protocol on its layer.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Four layers, four jobs
The TCP/IP model has four layers. The top one, application, is for services. It also takes in the jobs of OSI layers 5 and 6.
Transport numbers parts and delivers them. Internet gives IP addresses and picks routes. Network moves data over the local link. Many books call this last one link or network access. This course uses network.
The four TCP/IP layers
| TCP/IP layer | Its job | Protocols | OSI layers it covers |
|---|---|---|---|
| Application | Services for programs, format, scrambling and conversations | HTTP, HTTPS, FTP, SFTP, SMTP, POP, IMAP, DNS, DHCP | 7, 6 and 5 |
| Transport | Numbers parts and delivers them to the right program | TCP, UDP | 4 |
| Internet | IP addresses and routes across networks | IP, ICMP, OSPF, RIP | 3 |
| Network | Frames, MAC addresses and signals on the local link | Ethernet, Wi-Fi | 2 and 1 |
The cells students fill in are left blank in this preview.
Check
Have a go
Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.