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The
protocol provides reliable, flow-controlled, two-way transmission of data.
It is a byte-stream protocol used to support the abstraction. TCP uses
the standard Internet address format and, in addition, provides a per-host
collection of Thus, each address is composed of an Internet address specifying
the host and network, with a specific port on the host identifying the
peer entity. Sockets utilizing the tcp protocol are either or Active
sockets initiate connections to passive sockets. By default sockets are
created active; to create a passive socket the system call must be used
after binding the socket with the system call. Only passive sockets may
use the call to accept incoming connections. Only active sockets may
use the call to initiate connections. Passive sockets may their location
to match incoming connection requests from multiple networks. This technique,
termed allows a single server to provide service to clients on multiple
networks. To create a socket which listens on all networks, the Internet
address must be bound. The port may still be specified at this time;
if the port is not specified the system will assign one. Once a connection
has been established the socket’s address is fixed by the peer entity’s location.
The address assigned the socket is the address associated with the network
interface through which packets are being transmitted and received. Normally
this address corresponds to the peer entity’s network. supports one socket
option which is set with and tested with Under most circumstances, sends
data when it is presented; when outstanding data has not yet been acknowledged,
it gathers small amounts of output to be sent in a single packet once an
acknowledgement is received. For a small number of clients, such as window
systems that send a stream of mouse events which receive no replies, this
packetization may cause significant delays. Therefore, provides a boolean
option, (from to defeat this algorithm. The option level for the call
is the protocol number for available from Options at the transport
level may be used with see Incoming connection requests that are source-routed
are noted, and the reverse source route is used in responding.
A
socket operation may fail with one of the following errors returned:
when trying to establish a connection on a socket which already has one;
when the system runs out of memory for an internal data structure; when
a connection was dropped due to excessive retransmissions; when the remote
peer forces the connection to be closed; when the remote peer actively
refuses connection establishment (usually because no process is listening
to the port); when an attempt is made to create a socket with a port which
has already been allocated; when an attempt is made to create a socket
with a network address for which no network interface exists.
The protocol stack appeared in
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