flow and error control techniques in computer networks pdf Panola Texas

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flow and error control techniques in computer networks pdf Panola, Texas

So if station wants to send the packet D, still it won’t send. Create a clipboard You just clipped your first slide! That is, sender sends at a speed on which the receiver can process and accept the data. CSMA/CD Carrier Sense Multiple Access/Collision Detection a technique for multiple access protocols.

ALOHA ALOHA is a simple communication scheme in which each source in a network sends its data whenever there is a frame to send without checking to see if any other When the frame is successfully transmitted, B sends ACK frame. In wireless LANs it is not possible to listen to the medium while transmitting. This enforces the sender to retransmit all the frames which are not acknowledged.

Problems[edit] Explain hidden station and exposed station problem. When the sender sends all the frames in window, it checks up to what sequence number it has received positive acknowledgement. Single point of failure (token), token overhead, latency are the concerns in token passing. There are several issues in this protocol Hidden Station Problem Exposed Station Problem 1.

Theoretically it is proved that maximum throughput for ALOHA is 18%. Go-back-n ARQ

  • Damaged acknowledgement
    • Receiver gets frame i and send acknowledgement ( i+1 ) which is lost
    • Acknowledgements are cumulative, so next acknowledgement ( i+n ) may arrive before transmitter times If an acknowledgement of a data-frame previously transmitted does not arrive before the timeout the sender retransmits the frame, thinking that the frame or it’s acknowledgement is lost in transit. The Communication channel is assumed to be error free.

      Receiver accepts the frames and sends acknowledgment to the sender and passes the frames to the network layer and increases the expected sequence number from 4 to 7. If the channel is too noisy, when A send the frame to B and a frame is too large then there are more possibilities of the frame getting damaged and so Data-Link layer ensures that an initial connection has been set up, divides output data into data frames, and handles the acknowledgements from a receiver that the data arrived successfully. Your cache administrator is webmaster.

      Multiple access protocols are explained in the MAC layer section. Then all segments are added together using 1’s complement. Checksum checker Receiver receives the data unit and divides into segments of equal size of segments. The Media Access Control (MAC) and logical Link Control (LLC).

      If the remainder result in this division process is zero then it is error free data, otherwise it is corrupted. With the error control process, we can be confident that the transmitted and received data are identical. If the frame successfully reaches the destination, next frame is sent. Approaches of Flow Control Feed back based Flow Control Rate based Flow Control Feed back based Flow Control is used in Data Link Layer and Rate based Flow Control is used

      This protocol applies to slotted channels. Error Control[edit] Network is responsible for transmission of data from one device to another device. Automatic Repeat Request (ARQ)

      • Automatic repeat request
        • Error detection
        • Positive acknowledgment
        • Retransmission after timeout
        • Negative acknowledgement and retransmission
      • Stop and wait ARQ
      • Sliding window ARQ
      • – Go back N
      • – Selective In PCF, as it is centralized, no collision will occur.

        Two CSMA/C stations are trying to transmit long files. In this case the receiver accepts the frames 0 to 5 (which are duplicated) and send it to the network layer. Data unit is composite by number of 0s, which is one less than the divisor. In the response, if B wants to grant the permission, it will send the CTS packet to A giving permission to A for sending the packet.

        If station senses the medium idle, it starts transmitting the packet. Two types of mechanisms can be deployed to control the flow: Stop and Wait This flow control mechanism forces the sender after transmitting a data frame to stop and wait until The system returned: (22) Invalid argument The remote host or network may be down. Text is available under the Creative Commons Attribution-ShareAlike License.; additional terms may apply.

        There are four interval defined. When A receives its frame it starts ACK timer. See our Privacy Policy and User Agreement for details. By this we can identify the perfect location of error occurrence.

        Parity checking Parity adds a single bit that indicates whether the number of 1 bits in the preceding data is even or odd. Error Control

        • Used to recover lost or damaged PDUs
        • Involves error detection and PDU retransmission
        • Implemented together with flow control in a single mechanism
        • Performed at various protocol levels
        University of And if the frame fails to be received at the destination it is sent again. Sequence of segments is called a fragmentation burst.

        So the time out will occur after the 8 packets, up to that it will not wait for the acknowledgment. PCF and DCF can coexist within one sell. Station D is within B’s range but not A’s range. The end to end transfer of data from a transmitting application to a receiving application involves many steps, each subject to error.