Skip to main content

computer Networking- CCNA part 8 of Segment 1- Data Link Layer of OSI Model

OSI Model - Data Link Layer 

Hello friends once again i am vasu birla for discussing about second and most overloaded layer of OSI model  it is Data link Layer

Data Link Layer -  It is the second layer from the bottom of OSI layer. Some Important functions of data link are following -

Framing
Error Detection
Physical Addressing
Flow Control   .

  • Framing -  in the physical layer PDU (protocol data unit) is bit  it means in the physical layer data comes in form of bit or 0,1 form.  but later these different bits is converted in the frames combination of some 0s and 1s  the reason behind the framing is  easy error detection , so framing of data takes place in the data link layer.  

  • Error Detection - When each layer of OSI pass data to other layer so it include header also ,, but the only data link layer attach header and as well as trailer . There is value in this Trailer  that is known as FCS or Frame check sequence.  FCS value is a calculated value of our frame which helps for error detection.                                                                                                                                      Now the question is how FCS helps for error detection -  When Receiver receive data , it check this frame and compare it to FCS value and if both values (frame and FCS value) it means data is 100 % correct received and it is error free  and if values are not equal it means frame is corrupted.  so this function of data link layer is known as error detection. 

  • Physical Addressing -  Physcial address is identity of your physical system or computer and it is inbuilt on NIC (Network interface card) or on LAN card  . it never changed this is fixed and unique address of your system.  example of physical address is  MAC address which is made of 48 bits or 6 byes or 12 hexadecimal numbers.  

  • Flow control -  It means when there is too much data flowing over network so it may cause of slow connetion of huge data traffic problem  this may make network shut down  for solution of this problem Data link devices control flow of data in the network.  Devices which works on data link layer is bridges and traditional switches and these devices ensure us to deliver data successfully by dividing domains (we will discuss in details about devices and their working.)
Flow control by stop and wait  using acknowledgment of frames
     
Flow control using Switch  a data link layer Device






DATA Link Layer is further divided in Two SUB layers 
  • LLC (Logical Link Control) Layer
  • MAC(Media Access Control ) Layer 

WE will discuss these two sublayer in next part.... hare krishna ,.,



#ccna #cisco  #Networking 
Location Detected  

Sanawad Coordinates
22.1800° N, 76.0700° E
Labels:

Comments

Post a Comment

Popular posts from this blog

Part 15- What is Repeater (Networking Devices)- Computer Networking- CCNA

Repeater  hello friends i am Vasu Birla and today i am starting new segment of CCNA computer networking  its a Networking Devices. we will discuss every important Devices used in networks. Repeater is a first networking devices. What is Repeater  Repeater is a device that receives signals and re-transmits by amplifying or regenerating signals. Repeater has two port one is for receive signals from previous network and second port is for retransmit signals to the next extended network. Two Port Repeater Repeater is a device which is used to Regenerate or replicate signal (Pichhe se aa rahe signal ko regenerate karke ya amplify karke aage strong signals bhej sakte he) Analog and digital both type of signals can be retransmitted by repeater. Here there is difference between regeneration and amplifying.  Amplification means , received signals will be amplified as it is , whether there are impurities in signals  and Regeneration means repeate...
Post a Comment
Read more

How to Kill the Process: ( Port Process )

If you are seeing a Error like  -   Error: listen EADDRINUSE: address already in use :::3000   then you can easily kill it by running these commands  Find the Process Using Port 3006 : On Windows   netstat -ano | findstr :3000 On Linux/macOS lsof -i :3000       Terminate the Process :       On Windows taskkill /PID <PID> /F    means       taskkill /PID 17780 /F On Linux/macOS kill -9 <PID>     means kill -9 17780                ==============END ==========  
Post a Comment
Read more

Part 19- Router (Networking Devices)- Computer Networking- CCNA

Hello friends...i am Vasu Birla and today will discuss about the most important Networking Device ..Router.  so let's start... ROUTER Router is a device which connect two or more networks together, which is why router is also known is Inter-networking device also. Inter-networking means two or more networks are connected together with the help of router. one more thing router is just like a computer  but it is designed for routing only, our computer can be router also but that are software router while hardware router which are specialize for routing is more efficient and fast than software router.  There is a Operating System installed on router which get moves data from one network to another network with the help of routing table.  Router does work on Network layer or Layer 3 of the OSI model.  Cisco Router There many companies which manufacture Router but main companies are - Cisco , Juniper , HP, 3com and Nortel  ...
1 comment
Read more