Where is data link layer used?

[nigosawa]

hi
i want to ask is data link layer only used on LANs?....as i read in a book that when a packet is transfered from one router to another it is in network packet format. and when it reaches a LAN on which the destination computer is attached, the router encapsulates it in a data link layer frame


please elaborate

 

[manish12]

Re: data link layer

it is used in any network.

 

[Enhancer]

Re: data link layer

The meaning is come from a fact that:
Switch, can encapsulate the data up to layer 2 "DATA Link Layer"
Router, can encapsulate the data up to layer 3 "Network Layer"

and so,
on the level of the LAN, the only needed is "switch", which means that the devices in the LAN will read from Layer 1 up to only Layer 2. which yields to usage only of the first two layers in the OSI model in the LAN.

 

[III]

data link layer

The data link is the second layer in ISO-OSI (Open System Interconect) and egsists in every communication systems, not just 802.3 lans.
Actualy not all of the 7 layers of the osi have to egzist in a communication system but the lower layers allmost allways egzist.