AUTHOR: SMITH SOLACE
The Transmission Control Protocol (TCP) and the Internet Protocol (IP) together form the basis for TCP/IP, a low-level driver that lets computers talk to each other using a network of almost any size. The Internet is connected using TCP/IP as its foundation.
TCP/IP was proposed in 1973. Nine years later, in 1983, a standardized version of the protocol was developed and adopted for wide-area use. In 1983, it also became mandatory that all connections to ARPAnet, the Department of Defense’s predecessor to today’s Internet, be made with TCP/IP.
TCP/IP was developed to solve several problems in moving data from point A to point B. The most important requirement was to guarantee delivery of data on a network that might be under attack from a foreign power. Because the Department of Defense (DoD) developed the Internet, this requirement was paramount and fairly predictable. If an enemy were to attack the military’s computer systems and networks, data must continue to flow, secure and unhampered. The other established requirements were that data be moved efficiently and that its arrival be verified - yet the sending machine might not have any of the same operating characteristics as the receiving machine. TCP and IP both perform unique and vital functions that solve all the problems in moving data between machines over networks.
Transmission Control Protocol
TCP is the transmission layer of the protocol. Its primary function is to ensure reliable and verifiable data exchange between different hosts across a network. TCP performs its tasks by breaking data into manageable pieces and then wrapping the pieces with information called a header that routes the data to its final destination. TCP on the receiving machine then puts all the pieces back together, just as they were before the data was sent. The wrapped and bundled pieces are called datagrams.
The primary pieces of information in the TCP header are the source and destination port numbers, a sequence number for the datagram, and a checksum. Port numbers allow the data to be sent back and forth to the correct process running on each computer. (We cover ports in more detail later in this chapter.) The sequence number lets TCP reassemble the datagrams in the correct order. The checksum lets the protocol determine whether the data received is the data that was sent. The checksum calculates a number by adding all the octets of a datagram; this number is then inserted into the datagram’s header. The receiving computer performs the same calculation, and if the two calculations do not match, an error occurred somewhere along the line, and the datagram is resent.
After the TCP header is inserted into the datagram, TCP passes the datagram to the IP protocol to be routed to its final destinationshows the layout of a datagram with its TCP header structure.
Internet Protocol
IP is the network layer portion of TCP/IP. IP actually moves data from point A to point B across a network. This movement of data is called routing, and that’s really all IP does. (We cover routing in a bit more detail later in this chapter.) IP is typically considered unreliable, meaning that nothing guarantees that the data it routes will even arrive at its destination, much less in the order it was sent. IP relies on TCP to determine whether the data arrived successfully at its destination and to retransmit the data if it hasn’t.
To route data, IP inserts its own header into the datagram after it receives it from TCP. The contents of the IP header are the source and destination addresses, another checksum, and the protocol number. The header informs routers (or gateways) along the way of the datagram’s final destination. for a layout of a datagram complete with its TCP and IP headers. The IP header portion has a gray background.
The Transmission Control Protocol (TCP) and the Internet Protocol (IP) together form the basis for TCP/IP, a low-level driver that lets computers talk to each other using a network of almost any size. The Internet is connected using TCP/IP as its foundation.
TCP/IP was proposed in 1973. Nine years later, in 1983, a standardized version of the protocol was developed and adopted for wide-area use. In 1983, it also became mandatory that all connections to ARPAnet, the Department of Defense’s predecessor to today’s Internet, be made with TCP/IP.
TCP/IP was developed to solve several problems in moving data from point A to point B. The most important requirement was to guarantee delivery of data on a network that might be under attack from a foreign power. Because the Department of Defense (DoD) developed the Internet, this requirement was paramount and fairly predictable. If an enemy were to attack the military’s computer systems and networks, data must continue to flow, secure and unhampered. The other established requirements were that data be moved efficiently and that its arrival be verified - yet the sending machine might not have any of the same operating characteristics as the receiving machine. TCP and IP both perform unique and vital functions that solve all the problems in moving data between machines over networks.
Transmission Control Protocol
TCP is the transmission layer of the protocol. Its primary function is to ensure reliable and verifiable data exchange between different hosts across a network. TCP performs its tasks by breaking data into manageable pieces and then wrapping the pieces with information called a header that routes the data to its final destination. TCP on the receiving machine then puts all the pieces back together, just as they were before the data was sent. The wrapped and bundled pieces are called datagrams.
The primary pieces of information in the TCP header are the source and destination port numbers, a sequence number for the datagram, and a checksum. Port numbers allow the data to be sent back and forth to the correct process running on each computer. (We cover ports in more detail later in this chapter.) The sequence number lets TCP reassemble the datagrams in the correct order. The checksum lets the protocol determine whether the data received is the data that was sent. The checksum calculates a number by adding all the octets of a datagram; this number is then inserted into the datagram’s header. The receiving computer performs the same calculation, and if the two calculations do not match, an error occurred somewhere along the line, and the datagram is resent.
After the TCP header is inserted into the datagram, TCP passes the datagram to the IP protocol to be routed to its final destinationshows the layout of a datagram with its TCP header structure.
Internet Protocol
IP is the network layer portion of TCP/IP. IP actually moves data from point A to point B across a network. This movement of data is called routing, and that’s really all IP does. (We cover routing in a bit more detail later in this chapter.) IP is typically considered unreliable, meaning that nothing guarantees that the data it routes will even arrive at its destination, much less in the order it was sent. IP relies on TCP to determine whether the data arrived successfully at its destination and to retransmit the data if it hasn’t.
To route data, IP inserts its own header into the datagram after it receives it from TCP. The contents of the IP header are the source and destination addresses, another checksum, and the protocol number. The header informs routers (or gateways) along the way of the datagram’s final destination. for a layout of a datagram complete with its TCP and IP headers. The IP header portion has a gray background.
No comments:
Post a Comment