TCP?UDP????

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TCP?UDP????

• ? 22 ?
• b91902049 ??? b91902064 ???
• b91902067 ??? b91902077 ???

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TCP Overview (1/2)

• TCP creates "segments" or "user datagrams" by
  taking the information from the Application layer
  and adding a header to it. Since TCP is
  responsible for Port to Port addressing, it uses
  a 16bit process port to identify who it wants to
  talk to. This means that TCP deals with program
  to program, not machine to machine.

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TCP Overview (2/2)

• It works by opening up a stream or virtual
  circuit between the two ports, which begins by
  alerting the receiver to expect information and
  ends by an explicit termination signal. Since
  every segment received is answered with an
  acknowledge, TCP is a reliable stream delivery
  service. This just means that the information is
  "guaranteed" to arrive, or an error will be
  returned.

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TCP Header (1/9)
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TCP Header (2/9)

• Source Port Address (16)-The address of the
  application that is generating the segment.
• Destination Port Address (16)-The address of the
  application that will receive the segment.

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TCP Header (3/9)

• Sequence Number (32)-Position of data in the
  original data stream (if it has been split).
• Acknowledge Number (32)-Acknowledges the
  acceptance of data from the other device.

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TCP Header(4/9)

• H Len (4)-Header Length. Number of 4 byte words
  used in header (0-60 bytes).
• reserved (6)---reserved for future use--

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TCP Header (5/9)

• CONTROL URG (1)-Urgent Bit validates the
  Urgent Pointer field.
• CONTROL ACK (1)-Acknowledge Bit, set if the
  Acknowledge Number field is being used.

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TCP Header (6/9)

• CONTROL PSH (1)-Push Bit tells the sender that
  a higher throughput is required.
• CONTROL RST (1)-Reset Bit resets the
  connection when there's conflicting sequence
  numbers.

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TCP Header (7/9)

• CONTROL SYN (1)-Sequence Number
  Synchronization. Used in 3 types of segments
  connection request, connection confirmations
  (with ACK) and confirmation termination (with
  FIN) in 3 types of segments terminal request,
  terminal confirmation (with ACK) and
  acknowledgement of terminal confirmation (with
  ACK).

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TCP Header (8/9)

• CONTROL FIN (1)-Used with SYN to confirm
  termination of connections.
• Window Size (16)-Defines the size of the "sliding
  window.
• Checksum (16)-Error checking and correction.

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TCP Header (9/9)

• Urgent Pointer (16)-Valid if URG is set, it
  defines the end of the urgent data.
• Options and Padding (variable)-Additional
  information for alignment purposes (see below).

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TCP connection
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TCP Disconnection
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TCP Functionality (1/2)

• Streams. TCP data is organized as a stream of
  bytes, much like a file. The datagram nature of
  the network is concealed.
• Reliable delivery. TCP will arrange for
  retransmission if it determines that data has
  been lost.

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TCP Functionality (2/2)

• Network adaptation. TCP will dynamically learn
  the delay characteristics of a network and adjust
  its operation to maximize throughput without
  overloading the network.
• Flow control. TCP manages data buffers, and
  coordinates traffic so its buffers will never
  overflow. Fast senders will be stopped
  periodically to keep up with slower receivers