Hosts are any device which sends or receive traffic
Types
Client (request services)
Server (provide services)
Examples:
Computer
Laptop
Mobile
Printers
Servers
IoT Examples:
Speakers
Lights
Thermometer
Repeaters
Data crossing a wire decays as it travels
Repeaters regenerate signals
Allow communications across greater distances
Network Scaling
Connecting hosts directly to each other doesn’t scale since it will require each additional host connecting to network to connect to every other host in the network
Hubs, Switch, Router etc. solve the scale problem and sits in the center of the network
Hub
It is Layer-1 device
Client packets goes to Hub and Hub will duplicate the packets and send it out to all remaining ports it to every devices connected to it, All hosts except the recipient drops the packet
Since it is Layer 1 device, it does not manage any traffic
Bridge
It is a Layer-2 device
It sits between hub connected networks
It has only two ports
Bridge only allow the packet to pass if the recipient is on the other side of the bridge, else the packet is dropped
Bridges learn which host in which side
Switch
It is a Layer-2 device (can be Layer-3 in some cases)
Switching is the process of moving data within networks
Switch’s primary purpose is switching
Combination of Hubs and Switches
It has multiple ports unlike bridges (which is debatable)
It learns which hosts are on which port and only transfer data to that port only unlike hubs
Is often included in the router on a local network
Cannot be used to connect to a non-local network (like the internet)
Router
It is Layer-3 device
Routing is the process of moving data between networks
Router’s primary purpose is routing
Transfer data to nodes on non-local networks
Select the most efficient route for the data to take
Are used to connect to internet
Provide the traffic control point (security, filtering redirecting)
They maintain routing table which contains all the networks a router knows about
Create the Hierarchy in Networks and the entire Internet