a reliable end-to-end connection

routing to identify the path to a logical destination

identifying and cutting the frames and add the logical addresses

taking care of physical addressing to uniquely identify each machine

taking care of logical addressing

ensuring proper channel sharing

laptop

desktop

wifi access point

router

switch

wireless router

They are the first to transfer data that crosses the network

They filter data streams to enhance security

They route data on secondary paths

They provide a channel over which messages are transmitted

They serve as an interface between humans and communication networks

provides high-speed bandwidth to internal devices

usually administered by one or more service providers

connect to the Internet at a central point: a router

used by large companies to connect their office networks.

a network infrastructure that covers a wide geographic area

is a network infrastructure that covers a restricted geographical area.

It speeds up packet delivery

It makes protocol design easier

It prevents a technology deployed on one layer from affecting the others

It prevents devs from creating their own templates

It guarantees that a device on one of the layers will work on the next layer