basics
internet = joining networks together
component types:
| component | function | example |
|---|---|---|
| app | use network | zoom, spotify, amazon |
| host (node,src,sink,end-system) | supports apps | laptop, mobile |
| router (switch,node,hub,intermediary) | relay messages between links | access point, cable/dsl model |
| link (channel) | connect nodes | wire, wireless |
networks by scale
| scale | type | example |
|---|---|---|
| vicinity | PAN (personal) | bluetooth |
| building | LAN (local) | wifi, ethernet |
| city | MAN (metropolitan) | cable, DSL |
| country | WAN | large ISP |
| planet | internet | internet |
what should networks do?
- need modularity
- functionality:
- make/break connections
- find path thru network
- reliably and securely transfer info of arbitrary length, as fast as possible
- share bandwidth among users
- allow new hosts
protocols
- protocol stack = set of protocols in use
- layers are vertical - talk to peers up and down
- ex.
- TCP
- IP
- HTTP
- DNS
encapsulation
- protocol layering
- lower layer wraps higher layer content to deliver message - like sending letter in envelope
- each layer adds its own header - makes it easy to swap things out and hide info to connect diff systems
- but, overhead + bulky messages + hides important info
