Ethernet and OSI Model

Question

I have a dumb question, first of all sorry for that. i am learning now 7 OSI Layer models and i stumble across one thing. The Ethernet which is in the second Data Link Layer provides the end-to-end connection via LANs, right? Does it mean that even if i connect to Internet thru WiFi, somewhere my connection is running thru LANs?

Thanks

Answer 1

I am going to break my answer into points:

1.Lan is not necessary to connect to internet. You can have cable internet or internet through DSL connection etc. in which though the wire that comes and connect to your pc is the same cat5(for example) cable, there is no lan involved.

2.Internet through wireless router an be accessed in two ways:

(a)The ethernet cable from (say) a cable modem connects to your wireless router WAN port and then wireless router sends out radio waves which your laptop catches.

(b)There are many wireless routers and one cable internet connection. So the WAN port of one of the routers will connect to the cable modem(same as (a)) and from that router's ethernet ports(usually there are 4 ethernet ports on a wireless router ), ethernet cables will connect to other routers' ethernet ports and now these routers will send out radio waves which your pc catches.

3.Ethernet is one of the IEEE protocols(IEEE 802.3) for the data link layer. The wifi uses IEEE 802.11 standards to communicate through wireless media.

Answer 2

Short answer is: most likely

In your case, you only know your direct connectivity is made possible thru WiFi. From your perspective, it's just a WiFi network. But behind WiFi network, it could be Ethernet, DSL, Cable, etc. And behind those, it could be T1, frame relay, ATM, 10G or maybe 100G Ethernet, etc.

For example, I can have a small LAN at my home while my company office building can have a much bigger enterprise LAN. And both can provide me with the same kind of WiFi access.

Answer 3

Your connection to the nearest router is using a wifi data link protocol (in the IEEE 802.11 family). But the connections to other routers and (eventually) hosts will use other data link protocols, likely including ethernet at least at the far end.