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2-5-1 Special Application
Some applications require multiple connections, such as Internet gaming,
video conferencing, Internet telephony and others. These applications
cannot work when Network Address Translation (NAT) is enabled. When
users send this type of request to your network via the Internet, the Router
will forward those requests to the appropriate PC. If you need to run
applications that require multiple connections, specify the port normally
associated with an application in the "Trigger Port" field, select the
protocol type as TCP or UDP, then enter the public ports associated with
the trigger port to open them for inbound traffic.
• TCP (Transmission Control Protocol) - A communications method
(protocol) used along with the Internet Protocol (Internet Protocol) to
send data in the form of message units between computers over the
Internet. While IP takes care of handling the actual delivery of the
data, TCP takes care of keeping track of the individual units of data
(called packets) that a message is divided into for efficient routing
through the Internet.
• UDP (User Datagram Protocol) - A communications method
(protocol) that offers a limited amount of service when messages are
exchanged between computers in a network that uses the Internet
Protocol (IP). UDP is an alternative to TCP and, together with IP, is
sometimes referred to as UDP/IP. Like the Transmission Control
Protocol, UDP uses the Internet Protocol to actually send a data unit
(called a datagram) from one computer to another. Unlike TCP,
however, UDP does not provide the service of dividing a message
into packets and reassembling it at the other end. Specifically, UDP
doesn't provide sequencing of the packets that the data arrives in.
This means that the application program that uses UDP must be able
to make sure that the entire message has arrived and is in the right
order. Network applications that want to save processing time
because they have very small data units to exchange (and therefore
very little message reassembling to do) may prefer UDP to TCP.