User`s guide

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TCP/IP Network Basics
TCP/IP Protocols
As each packet is sent from the source host, an acknowledgement of
receipt is sent by the destination host within a specified time. If the
acknowledgement is not sent within this time, the sender re-sends the
packet.
If the receiver gets the packet in a damaged condition, the packet is
discarded and the receiver sends no acknowledgement. In this case, since
an acknowledgement was not received in the specified time, the sender re-
sends the packet. This figure shows a network in which the source and
destination are using TCP and summarizes the steps to use TCP for
communication between hosts.
User Datagram
Protocol (UDP)
User Datagram Protocol (UDP) is used for connectionless, non-guaranteed
communication. Unlike TDP, UDP does not set up a connection and does
not use acknowledgements. Instead, UDP sends out packets without waiting
for acknowledgement from the destination.
Router
Source Destination
Steps
1. Source sends a packet to destination to set up communication.
2. Destination sends acknowledgement to establish communication.
3. Source sends another packet that confirms connection.
4. Source sends a data packet and waits for destination acknowledgement.
5. If acknowledgement is not received, source re-sends the packet.
If acknowledgement is received, source sends the next packet.
TCP Communication