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hello what happens when one of packets (of a particular file)is discarded by the intermediate router my doubt is, who will send the acknowlege about the lost packet , either ...
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  1. #1
    Linux Newbie
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    Oct 2006
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    connection oriented service


    hello

    what happens when one of packets (of a particular file)is discarded by the intermediate router

    my doubt is, who will send the acknowlege about the lost packet , either corresponding router / final reciever host, when the conection stream is "SOCK_STREAM"

    pls help me...........

    Thanks

  2. #2
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    SOCK_STREAM means you are using TCP. TCP is designed to retransmit lost packets. When a packet is lost, nobody does anything. After a timeout the server will re-transmit to lost packet.

    It will keep retransmitting until the client acknowledges the packet or it gives up and throws an error. The ack from the client will refer to the sequence number of the packet it has been sent in response to so the server can keep track of what has been received correctly.

    Does that answer your question?

    Chris...
    To be good, you must first be bad. "Newbie" is a rank, not a slight.

  3. #3
    Linux Newbie
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    connection oriented service

    hello,

    thanks for your answer.

    As you said that server only only will take care of lost packets.

    And one more doubt is there, please clarify this one tooo..

    After the connection establishment take place between client and server, do all the packets travell in the same path as the connection was?
    can the packets take the same route or they may take several routes depending on traffic..etc..

    Thanks

  4. #4
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    Quote Originally Posted by mallik
    After the connection establishment take place between client and server, do all the packets travell in the same path as the connection was?
    can the packets take the same route or they may take several routes depending on traffic..etc..
    I would say they should, and most of the time they will, but it is not a rquirement. The networking equipment (routers and so forth) between the client and the server ought to be set up to find the best path for the packets being sent. However that best path may change with time, power cuts, taiwanese earthquakes or, as you suggest, traffic loading.

    Network nodes can be configured to automatically route around damage to the network by dynamically altering routing tables. This can happen during a connection and nobody will ever notice (although it would be detectable). In fact I once investigated getting an arrangement with a neighbour so if my ISP failed my router would switch to routing my traffic through my neighbour's wireless network but he was non-techy so it didn't work out.

    It's also worth noting that the path from the client to the server doesn't need to match the path from the server to the client. That is one of the reasons for the three way handshake to set up connections; it verifies to both ends that the link works in both directions.

    Finally, the path the packet takes can be determined via source routing, but I've never seen it used and I'm pretty sure lots of people disallow it because it can be used to cause problems.

    I hope that helps,

    Chris...
    To be good, you must first be bad. "Newbie" is a rank, not a slight.

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