Computer Network

Question

What is the difference between broadcasting at Data Link Layer and broadcasting at Network Layer? Broadcasting at Data Link Layer is done via MAC address FF:FF:FF:FF:FF:FF while broadcasting at Network Layer is done using broadcast IP address 255.255.255.255 but they essentially do the same thing, sending a packet to every other node in the network.

Comments

What is the difference between broadcasting at Data Link Layer and broadcasting at Network Layer? 

here both are same ....during broadcast....we set ip ..255.255.255.255 then it comes to DLL then in next process it doesn't make a ARP request ....like unicast...it set MAC field  FF:FF:FF:FF:FF:FF and transfer on the corresponding link....

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broadcasting at dll, means you can able to send broadcast msg to any of the active node in your network(only in your network).

broadcasting at nl, means you can able to send the broadcast msg within your network as well as outside of your network.

generally broadcast msg of dll is discarded by the router itself, thus it can not able to propagate outside of it's home network.

Answer 1

1. In the case of Limited Broadcasting(Broadcasting within same network)
   Even though broadcasting is done at the Network layer, we can’t implement it without the support of the broadcasting feature of the Data Link layer.
   So, we can say the internet layer doesn’t have the broadcasting concept, Only the Data Link layer has.

2. In the case of Directed Broadcasting(Broadcasting in another network)
   Network layer sets Destination IP as Directed broadcast address, Correspond to DLL will set Directed broadcast MAC address, Router will forward this packet ahead, the network in which we want to send a broadcasting message, exactly ahead of it, Router will set that Directed broadcast MAC address to Limited broadcast MAC address and then it will send it the network, now due Limited broadcast MAC address even if this network is connected with some other network then still packet will not be forwarded ahead.

 

Comments

what is directed broadcast mac address ?