Receiving
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... TCP is
actually transmitted the sending user indicates that it should be
pushed through to the receiving user. A push causes the TCPs to
promptly forward and deliver data up to that point to the receiver.
...
... promptly forward and deliver data up to that point to the receiver.
The exact push point might not be visible to the receiving user and
the push function does not supply a record boundary marker.
...
... transmitted, and requiring a positive acknowledgment (ACK) from the
receiving TCP. If the ACK is not received within a timeout
...
... TCP places the data from a segment
into the receiving user's buffer and notifies the receiving user. The
...
... into the receiving user's buffer and notifies the receiving user. The
TCPs include control information in the segments which they use to
...
... An acknowledgment by TCP does not guarantee that the data has been
delivered to the end user, but only that the receiving TCP has taken
the responsibility to do so.
...
... flow of data between TCPs, a flow control mechanism is
employed. The receiving TCP reports a "window" to the sending TCP.
...
... This window specifies the number of octets, starting with the
acknowledgment number, that the receiving TCP is currently prepared to
receive.
...
... SEND call whether the data
in that call (and any preceeding calls) should be immediately pushed
through to the receiving user by the setting of the PUSH flag.
...
... segments at its own convenience, until the push
function is signaled, then it must send all unsent data. When a
receiving TCP sees the PUSH flag, it must not wait for more data from
the sending TCP ...
... TCP sees the PUSH flag, it must not wait for more data from
the sending TCP before passing the data to the receiving process.
...
...
The purpose of push function and the PUSH flag is to push data through
from the sending user to the receiving user. It does not provide a
record service.
...
... TCP/user interface. Each time a PUSH flag is
associated with data placed into the receiving user's buffer, the
buffer ...
... TCP does not attempt to
define what the user specifically does upon being notified of pending
urgent data, but the general notion is that the receiving process will
take action to process the urgent data quickly.
...
...
SEG.ACK = acknowledgment from the receiving TCP (next sequence
number expected by the receiving ...
... TCP to
maintain a zero receive window while transmitting data and receiving
ACKs. However, even when the receive window is zero, a TCP ...
... synchronization using data-carrying
segments, this is perfectly legitimate, so long as the receiving TCP
doesn't deliver the data to the user until it is clear the data is
...
... this, a special control message, reset, has been devised. If the
receiving TCP is in a non-synchronized state (i.e., SYN ...
... SYN-SENT,
SYN-RECEIVED), it returns to LISTEN on receiving an acceptable reset.
If the TCP is in one of the synchronized states (ESTABLISHED,
...
... by the
user at site B to send any data on it will result in the site B TCP
receiving a reset control message. Such a message indicates to the
site B TCP ...
... subject to ambiguous
interpretation, of course, since it may not be obvious how to treat
the receiving side of the connection. We have chosen to treat CLOSE
in a simplex fashion. The user who CLOSEs may continue to RECEIVE
...
... can ACK this FIN. Note that a TCP receiving a FIN will ACK but not
send its own FIN until its user has CLOSED the connection ...
... elapsed time between sending a data octet with a
particular sequence number and receiving an acknowledgment that
covers that sequence number (segments ...
... The objective of the TCP urgent mechanism is to allow the sending user
to stimulate the receiving user to accept some urgent data and to
permit the receiving TCP ...
... to stimulate the receiving user to accept some urgent data and to
permit the receiving TCP to indicate to the receiving user when all
...
... permit the receiving TCP to indicate to the receiving user when all
the currently known urgent data has been received by the user.
...
... least one octet of new data even if the send window is zero. The
sending TCP must regularly retransmit to the receiving TCP even when
the window is zero. Two minutes is recommended for the retransmission ...
... destination TCP
will have the urgent pointer set. The receiving TCP will signal
the urgent condition to the receiving ...
... receiving TCP will signal
the urgent condition to the receiving process if the urgent
pointer indicates that data preceding the urgent pointer has not
been consumed by the receiving ...
... receiving process if the urgent
pointer indicates that data preceding the urgent pointer has not
been consumed by the receiving process. The purpose of urgent
is to stimulate the receiver to process the urgent data and to
...
... TCP signals urgent will not necessarily be equal to the number
of times the receiving user will be notified of the presence of
urgent data.
...
... If there is urgent data the user will have been informed as soon
as it arrived via a TCP-to-user signal. The receiving user
should thus be in "urgent mode". If the URGENT flag is on,
additional urgent data remains. If the URGENT flag is off, this
...
... This is the next sequence number to be acknowledged by the
data receiving TCP (or the lowest currently unacknowledged
sequence number ...
... This represents the sequence numbers the local (receiving) TCP
is willing to receive. Thus, the local TCP ...
... This represents the sequence numbers which the remote
(receiving) TCP is willing to receive. It is the value of the
window field specified in segments ...
... window field specified in segments from the remote (data
receiving) TCP. The range of new sequence numbers ...
... A control bit (urgent), occupying no sequence space, used to
indicate that the receiving user should be notified to do
urgent processing as long as there is data to be consumed with
sequence numbers ...