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Group 6 - Coggle Diagram
Group 6
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Purpose and function of the data link layer in preparing communication for transmission on specific media.
Message Segmentation
- Large stream of data area divided into smaller and more manageable pieces to send over the network.
- By sending smaller pieces, this allowed many different conversations be interleaved on the network which is called MULTIPLEXING.
- Each pieces must be labeled and if any part of message is missing, only the part that is missing needs to be retransmitted.
Protocol Data Units
- As the application data passed down, the protocol stack and information is added to each level.
This is known as Encapsulation Process
- The data will take a form at each level and it is called Protocol Data Units(PDU).
- Protocol Data Units Level:
-Data= Application layer PDU
-Segment= Transport Layer PDU
-Packet= Network Layer PDU
-Frame= Data Link PDU
-Bits= Physical Layer PDU
ENCAPSULATION
The encapsulation work from top to bottom as the following: - Data is divided into segments.
-The TCP segment is encapsulated into the IP Packet.
-The IP Packet then is encapsulated into the Internet Frame.
DE-ENCAPSULATION
The de-encapsulation works from the bottom to top
De-encapsulation is use to remove one or more of the protocol header
-The data is de-encapsulated as it moves up from the stack toward the end-user application.
Network Addresses -is responsible for delivering the IP packet from original source to its final destinationSource IP address
- the IP address of the original source of the packet or the sending device.
Destination IP address
- the IP address of the receiving device or the final destination of the packet.
DATA LINK ADDRESS
-data link address deliver the data link frame from one network interface to another network interface on the same network.
- as the IP packet travels from source to destination it is encapsulated in a new data link frame when it is forwarded by each router.
DEVICES ON THE SAME NETWORK
- Network layer address or IP address show the original source and the final destination
- NETWORK PORTION: the left most part of the address that indicate which network is the IP part of
-HOST PORTION: The remaining part of the address that identifies specific devices on the network.
The Data Link Frame uses MAC addressing which send it directly to the receiving device.
DEVICE ON REMOTE NETWORK
-The source and the final destination IP addresses are represent host on different networks.
- The data link frame cannot ne send directly to the remote destination host. Therefore, the frame is sent to the default gateway which is the nearest to the router interface.
- The router remove the received Layer 2 information then adds a new data link information before forwarding to the exit interface.