Onno W. Purbo, YC1DAV/VE3
yc1dav @ ve3euk.@swon.on.can.na
yc1dav @ w2xo.#wpa.pa.usa.na
Department of Electrical and Computer Engineering
University of Waterloo
Waterloo, Ontario
CANADA N2L 3G1
yc1dav @ w2xo.#wpa.pa.usa.na
Department of Electrical and Computer Engineering
University of Waterloo
Waterloo, Ontario
CANADA N2L 3G1
The working principle of the network protocol TCP / IP is described in outline. Some commonly used applications on a computer network TCP / IP will be presented. Possibility of developing a Wide Area Network (WAN) using TCP / IP in Indonesia will also be explained. For example, the author's experience running a PC in the amateur radio related to the network AMPRNet - Internet uses the TCP / IP in Canada will be explained.
Introduction.
Many computer communication protocols have been developed to form a computer network. Competition among computer companies such as DEC, IBM etc.. spawned a variety of standard computer network. This raises difficulties, especially if it will be the interconnection between different types of computers in a wide area.
Around the 70's the Department of Defense (DoD) in the United States pioneered the development of computer network protocols that did not bound to the type of computer or communications media used. The protocol was developed called Internet Protocol (at the network layer) [1] and Transmission Control Protocol (the transport layer) [2] or abbreviated TCP / IP. Various additional protocol was then developed to solve various problems in a TCP / IP. Computer networks using TCP / IP is now better known as the Internet network. It appears that the Internet evolved from the needs and implementation in the field so that these computer networks continue to be refined. Currently TCP / IP is the standard in the UNIX operating system with the included socket library for accessing UNIX programmers directly to the TCP socket. All the standard used on the network TCP / IP can be obtained for free from various computers on the Internet.
In addition to TCP / IP protocol family actually developed by OSI / ISO as X.25/X.75/X.400 also began to be used by some institutions. Unfortunately all the information about this protocol must be purchased by us to the ISO. This led to development of the ISO / OSI choked unlike TCP / IP. For the longer term, the possibility of TCP / IP will become the world standard computer network. In this article will explain the working principle of the TCP / IP.
Layer protocols in computer networks.
In general, the protocol layer in a computer network can be divided into seven layers. This layer can be seen in Figure 1. From lowest to highest layer of known physical layer, link layer, network layer, transport layer, session layer, presentation layer and application layer. Each layer has the function of each and do not depend on one another.
From the seventh layer is only a physical layer is the hardware that the rest is software. physical layer is a media liaison to transmit digital information from one computer to another that can physically see. Various forms of hardware have been developed for this purpose. One of them is quite widely used for local computer networks (LAN) in Indonesia is ARCnet is widely used to use Novell software. For the purposes of Wide Area Network (WAN) can we could connect the various LANs uses the medium of radio or telephone into one unit.
To regulate the relationship between the two computers through the existing physical layer link layer protocol used. In packet radio networks used in amateur AX.25 link layer (Amateur X.25) X.25 CCITT which is a derivative which is also used in Packet Data Communication System (SKDP) by PT. INDOSAT and PERUMTEL. In the previous article described about <xysical layer and link layer used on the Wide Area Network (WAN) using amateur packet radio technology.
IEEE organization for the electrical engineering profession has developed several standard physical layer protocol and link layer for the LAN. Based on the IEEE recommendation on the use of ARCnet LAN (IEEE 802.3) or Ethernet (IEEE 802.3) used link layer (IEEE 802.2). In use Token Ring LAN physical layer (IEEE 802.5). Another form of LAN is less known is the Token Bus (IEEE 802.4). For high-speed LAN also has developed a standard derived from the IEEE 802.3 that became known as the Fiber Distributed Data Interface (FDDI).
This article will focus the discussion on the protocol layer network layer and transport layer. Actually there are some other protocol families in the TCP / IP. Shown in Figure 2 in addition to the IP network layer is also known as ICMP (Internet Control Message Protocol) [3], ARP (Address Resolution Protocol) [4], and RARP (Reverse Address Resolution Protocol). At the transport layer used UDP (User Datagram Protocol) [5] other than TCP. For a while the discussion will be limited to the working principle of the IP protocols TCP damn. This is because TCP / IP is the protocol most often used in network operation, is a complement to other protocols that help these networks work. It should be noted that in computer networks using TCP / IP is generally done by the top three layers of the operating system of the computer being used. Especially for computers that use UNIX has been available for network programming library so that we can develop your own program with direct access to TCP sockets are available. Maybe on the other opportunity will be explained further on how the TCP socket programming in UNIX that can be accessed using the C language
The working principle of the Internet Protocol (IP).
The function of the Internet Protocol can be simply explained as the workings of the post office on mail delivery process. We input a letter to the mailbox will be taken by the postman and then be sent through a random route, without the sender and the recipients know the traveling path of the letter. Also if we send two letters to the same address on the same day, not necessarily because it may be up to the same letter that one would take a different route with another letter. In addition, there is no guarantee that the letter would reach the hands of destination, unless we send them using registered mail.
Above principle is used by Internet Protocol, "the letter" above is known as a datagram. Internet protocol (IP) functions deliver a datagram from one computer to another without depending on the medium used kompunikasi. The data transport layer is cut into datagram-datagram that can be carried by IP. Each datagram is removed in a computer network and will find themselves automatically route to be taken to the destination computer. This is known as connectionless transmission. In other words, the computer sending the datagram did not know whether the datagram will arrive or not.
To help reach the destination computer, each computer in a TCP / IP must be given an IP address. IP address must be unique for each computer, but not be an obstacle when a computer has multiple IP addresses. IP addresses consist of 8 bytes of data that has a value of 0-255 which is often written in the form [xx.xx.xx.xx] (xx has a value from 0-255).
In the Internet Protocol header in addition to the IP address of the destination computer and the computer sending the datagram there are also some other information. This information includes the type of transport protocol layer is superimposed over IP. Shown in figure 2 there are two types of protocol at the transport layer are TCP and UDP. Other important information is the Time-To-Live (TTL) which determines how long the IP can live on the network. TTL value will be reduced by one if the IP through a computer. This is important mainly because the IP is removed in a computer network. If for some reason could not find the IP address of the destination with the IP TTL will die by itself when the TTL is zero. Besides, also each given identification IP forwarding so that together with the IP address sending computer data and the destination computer, each IP in the network is unique.
Especially for users of computer networks are the most important thing to understand it really is the concept of an IP address. Institutions that set the IP address is the Network Information Center (NIC) in the Department of Defense in the U.S. located at hostmaster@nic.ddn.mil. IP address setting is important, especially when the routing automatically. As an example of a computer network in amateur radio have a class that has the IP address address [44.xx.xx.xx]. Especially for amateur radio in Indonesia the IP address used is [44.132.xx.xx]. While writers in Canada have an IP address [44.135.84.22]. This can be seen clearly that the IP address in the amateur radio geographical nature. From writer-readable IP addresses that machines on a network 44 writers on the Internet, known sabagai AMPRNet (ampr.org). 135 signifies that the author was in Canada. 84 tells us that the author was in the city of Waterloo in Ontario province, while 22 is the engine number writer. With the concept of IP addresses, IP traveled route in the network computer can be done automatically. For example, if a computer on the Internet will send the IP [44.135.84.22], first released in the IP network will try to find a way to network 44.135.84, after the machines that connect the IP network 44.135.84 achieved will try to contact 22 machines in the network. All this is done automatically by the program.
Surely it is difficult for humans to remember so many IP addresses. For ease, developed the Domain Name System (DNS). For example, authors in AMPRNet machine with the IP address [44.135.84.22], the authors give the name (hostname) ve3.yc1dav.ampr.org. Seen that the hostname used writer is very specific and very easy to learn that the author was in AMPRNet of ampr.org said. The machine was located in Canada and the provinces of Ontario currently YC1DAV ve3 is a writer himself. Another example of the DNS is sun1.vlsi.waterloo.edu which is a Sun SPARC workstation (sun1) in the VLSI research group at the University of Waterloo, Canada (waterloo.edu) where the author's work and learn. It should be noted that the current NIC domain not given to Indonesia. Hopefully with the development of computer network TCP / IP in Indonesia there are times when we in Indonesia have asked for a separate domain for Indonesia.
The working principle of the Transmission Control Protocol (TCP)
Unlike the Internet Protocol (IP), TCP has the working principle of such "virtual circuit" on the telephone network. TCP is more concerned with know-how and reliability in data transmission between two computers in the network. TCP does not care what is done by IP, which is important is the communication link between two computers running well. In this case, the TCP setting out how to open links of communication, what kind of applications will be done in such communications (eg sending e-mail, file transfer etc.). In addition, it also detects and corrects data errors if any. TCP governs the whole process of connection between one computer to another computer within a computer network.
In contrast to the connectionless IP mechanisms that rely on TCP is connection-oriented mechanism of the relationship. In this case, the logical relationships to be built by TCP from one computer to another computer. Within the specified computer that is connected to send data or acknowledge that the relationship continues. If this can not be done then it can be assumed that the computer is in contact with us disorders and logical relationship may be terminated.
TCP multiplexing set of data sent / received by a computer. The identification of the TCP header allows the multiplexing performed. This allows a computer to do some logical TCP connection. Form of relationship is full duplex, this allows two computers talk to each other at the same time without having to take turns using the channels of communication. To overcome the saturation (congestion) on the communication channel, the TCP header has information about flow control.
It is quite important to understand the TCP port number is. Port number to determine the services performed by the application program over TCP. These numbers have been determined by the Network Information Center in the Request For Comment (RFC) 1010 [10]. As an example for the application File Transfer Protocol (FTP) over TCP transport layer used port number 20 and many more.
The working principle of the TCP based client-server principle. Server is a program on a computer that will passively listen (listen) port number specified in the TCP. 're Client is a program that actively opens a TCP connection to the server computer to request the services needed.
Working TCP state diagram shown in Figure 3. In the state diagram of figure 3, the client will actively open a connection (active open) by sending a SYN signal (SYN Sent state) to a destination server computer. If the server receives the SYN signal the server when it is in LISTEN state will send a signal SYN and the two computers (client & server) going to the ESTAB state. If no response from the destination computer, then the program will return to the state CLOSE. After the service performed has been completed then the client will send the wrong signals FIN and client computers will be in state FIN FIN WAIT until the signal is received from the server. On receipt of the FIN signal, the server to the state CLOSE WAIT until the connection is disconnected. Finally, both computers will be back on the state CLOSE.
Some examples of applications of the Internet
Many applications are possible using a family of TCP / IP. Typical applications are the electronic delivery of news, known as electronic mail (e-mail). It developed a protocol for Simple Mail Transfer Protocol (SMTP) [6]. The protocol sets out procedures for transmitting messages from a user on a computer to another using a unique address. For example, e-mail me at AMPRNet are:
yc1dav@ve3.yc1dav.ampr.org
which means that the author YC1DAV was in (at, @) ve3.yc1dav.ampr.org machine. Certainly at the time of delivery of news, the IP will do the conversion of hostnames to IP addresses ve3.yc1dav.ampr.org author [44.135.84.22] to then send the information to be included in the SMTP protocol TCP.
Another application is the remote login to a remote computer. This is done by using the Telnet facility [7] run over the TCP transport layer. To perform file transfers use File Transfer Protocol (FTP) [8] which is also run over TCP. With the growing complexity of the network, network management becomes crucial. Currently developed a special protocol to be used to manage the network as Simple Network Management Protocol (SNMP) [9]. There are many other applications that run on top of TCP, such as NNTP, etc. RSPF. Each application has a unique TCP port number.
One thing is quite interesting with the use of TCP / IP is the possibility to connect multiple computer networks using different communication media. In other words, the computer connected to the network using ARCnet, Ethernet, Token Ring, SKDP, amateur packet radio, etc.. can talk to each other without knowing each other that communication media that are used physically different. This makes it possible to easily form a Wide Area Network in Indonesia. Currently UNINET pioneered by colleagues from PUSILKOM-UI was faltering mainly because of the high cost that must be spent for communication. In addition, the protocol used in networks today is the UUCP UNINET which is basically a very simple protocol. It is not possible UNINET to do things that are possible only by the TCP / IP such as automated network management using SNMP and relationships as it is done using a connectionless IP.
To further clarify, it's good real world examples the authors put forward by the author in amateur packet radio network (AMPRNet) in Canada. Broadly speaking, computer network topology packet radio amateurs in Waterloo shown in Figure 4. Currently the network AMPRNet in Waterloo working on The frequency of 145.09MHz at 1200bps speed. We plan for upgrading the network TCP / IP available to the speed of 9600bps. In the picture's written some of the machines of friends and writers such as at.ve3euk.ampr.org home.ve3rks.ampr.org.
Here we have a gateway at.ve3uow.ampr.org's University of Waterloo - Amateur Radio Club (ARC UoW), which the authors are also members, is the gateway connecting networks AMPRNet with Token Ring LAN PC network at the University of Waterloo. Through a gateway that is in a Token Ring network, the IP sent by the machine in AMPRNet may be associated with the Unix machines in the Ethernet network at UoW or with other machines on the Internet. There is not much between AMPRNet and Internet gateways that operate in the world today. It can be seen in the previous article writers on the author's experience working in amateur packet radio networks abroad.
At Waterloo we use sunee.waterloo.edu AMPRNet and watserv1.waterloo.edu as domain name server (DNS). In other words, using the protocol UDP / IP machines AMPRNet at Waterloo if it will relate to other machines on the Internet that hostnamenya AMPRNet or known to ask for the IP address of the destination machine to the DNS. All this is done automatically without the need for machine operators know the process occurs.
With the technology in the world of amateur radio amateur packet radio. The possibility of developing low-cost WAN in Indonesia became possible. UNINET AMPRNet because it is not possible using amateur packet radio is not familiar with UUCP. Even if forced amateur radio must develop the necessary software from scratch. The use of TCP / IP will make it easier internetwoking with various networks like AMPRNet thereby opening the possibility of developing cost WAN easy, but with a much better facility than the UUCP.
Cover
General working principle of using the family computer network protocol TCP / IP has been described in outline. Some examples of usage and the possibility to form a WAN using TCP / IP has been described. Some articles / books that might provide a fairly in-depth information about the working principle of the network using TCP / IP can be obtained in RFC 1122 [12] and RFC 1123 [13]. Copies of RFCs can be obtained from the Network Information Center (NIC) located at:
DDN Network Information Center
SRI International
333 Ravenswood Avenue
Menlo Park, CA 94025
U.S.A.
tel: 800-235-3155
For those of us who are overseas, simply copy the RFC can we get for free by doing an FTP to NIC.DDN.MIL. Several copies of the RFC in the form of a compressed file on a diskette has the writer sent to Indonesia. Currently the files in a diskette containing the RFC on TCP / IP, the program KA9Q TCP / IP and source code that I use for my work in the network AMPRNet, most likely can be obtained from Dr. Kusmayanto Kadiman (chairman PIKSI-ITB), Ir. A. Mas'ud (PAU Microelectronics ITB), Dr. S. Nasserie (Department of Electrical Engineering ITB), magazine editor and ITB Electron Amateur Radio Club. The author hopes this article will give general overview of computer networks TCP / IP and the possibility of its development in Indonesia.
REFERENCES
[1] J. Postel, "RFC 791: Internet Protocol (IP)," Internet Network Working Group, September 1981.
[2] J. Postel, "RFC 793: Transmission Control Protocol," Internet Network Working Group, September 1981.
[3] J. Postel, "RFC 792: Internet Control Message Protocol," Internet Network Working Group, September 1981.
[4] D.C. Plummer, "RFC 826: An Ethernet Address Resolution Protocol," Internet Network Working Group, November 1982.
[5] J. Postel, "RFC 768: User Datagram Protocol," Internet Network Working Group, August 1980.
[6] J. Postel, "RFC 821: Simple Mail Transfer Protocol," Internet Network Working Group, August 1982.
[7] J. Postel and J. Reynolds, "RFC 854: Telnet Protocol Specification," Internet Network Working Group, May 1983.
[8] J. Postel and J. Reynolds, "RFC 959: File Transfer Protocol (FTP)," Internet Network Working Group, October 1985.
[9] J. Case, M. Fedor, M. Schoffstall and C. Davin, "RFC 1098: A Simple Network Management Protocol," Internet Network Working Group, April 1989.
[10] J. Reynolds and J. Postel, "RFC 1010: Assigned Numbers," Internet Network Working Group, May 1987.
[12] R. Braden, "RFC 1122: Requirements for Internet Hosts - Communication Layers," Internet Network Working Group, October 1989.
[13] R. Barden, "RFC 1123: Requirements for Internet Hosts - Application and Support," Internet Network Working Group, October 1989.
DESCRIPTION OF FIGURES
Figure 1 The seven layer protocol used in a computer network in accordance with recommendations issued by the OSI / ISO.
Figure 2 family of protocols in computer networks using TCP / IP. It appears that in addition to TCP / IP is also used some of the additional protocol. It should be noted that the protocol presented above is only a part of the protocol known.
Figure 3 State diagram simply of the Transmission Control Protocol (TCP). The principle used in client-server interaction, two computers using TCP.
Figure 4 Example of network topology AMPRNet in Waterloo, Canada linked via at.ve3uow.ampr.org to Token Ring PC network and then through the Ethernet network and the machine watmath.waterloo.edu related to the Internet computer network.
Introduction.
Many computer communication protocols have been developed to form a computer network. Competition among computer companies such as DEC, IBM etc.. spawned a variety of standard computer network. This raises difficulties, especially if it will be the interconnection between different types of computers in a wide area.
Around the 70's the Department of Defense (DoD) in the United States pioneered the development of computer network protocols that did not bound to the type of computer or communications media used. The protocol was developed called Internet Protocol (at the network layer) [1] and Transmission Control Protocol (the transport layer) [2] or abbreviated TCP / IP. Various additional protocol was then developed to solve various problems in a TCP / IP. Computer networks using TCP / IP is now better known as the Internet network. It appears that the Internet evolved from the needs and implementation in the field so that these computer networks continue to be refined. Currently TCP / IP is the standard in the UNIX operating system with the included socket library for accessing UNIX programmers directly to the TCP socket. All the standard used on the network TCP / IP can be obtained for free from various computers on the Internet.
In addition to TCP / IP protocol family actually developed by OSI / ISO as X.25/X.75/X.400 also began to be used by some institutions. Unfortunately all the information about this protocol must be purchased by us to the ISO. This led to development of the ISO / OSI choked unlike TCP / IP. For the longer term, the possibility of TCP / IP will become the world standard computer network. In this article will explain the working principle of the TCP / IP.
Layer protocols in computer networks.
In general, the protocol layer in a computer network can be divided into seven layers. This layer can be seen in Figure 1. From lowest to highest layer of known physical layer, link layer, network layer, transport layer, session layer, presentation layer and application layer. Each layer has the function of each and do not depend on one another.
From the seventh layer is only a physical layer is the hardware that the rest is software. physical layer is a media liaison to transmit digital information from one computer to another that can physically see. Various forms of hardware have been developed for this purpose. One of them is quite widely used for local computer networks (LAN) in Indonesia is ARCnet is widely used to use Novell software. For the purposes of Wide Area Network (WAN) can we could connect the various LANs uses the medium of radio or telephone into one unit.
To regulate the relationship between the two computers through the existing physical layer link layer protocol used. In packet radio networks used in amateur AX.25 link layer (Amateur X.25) X.25 CCITT which is a derivative which is also used in Packet Data Communication System (SKDP) by PT. INDOSAT and PERUMTEL. In the previous article described about <xysical layer and link layer used on the Wide Area Network (WAN) using amateur packet radio technology.
IEEE organization for the electrical engineering profession has developed several standard physical layer protocol and link layer for the LAN. Based on the IEEE recommendation on the use of ARCnet LAN (IEEE 802.3) or Ethernet (IEEE 802.3) used link layer (IEEE 802.2). In use Token Ring LAN physical layer (IEEE 802.5). Another form of LAN is less known is the Token Bus (IEEE 802.4). For high-speed LAN also has developed a standard derived from the IEEE 802.3 that became known as the Fiber Distributed Data Interface (FDDI).
This article will focus the discussion on the protocol layer network layer and transport layer. Actually there are some other protocol families in the TCP / IP. Shown in Figure 2 in addition to the IP network layer is also known as ICMP (Internet Control Message Protocol) [3], ARP (Address Resolution Protocol) [4], and RARP (Reverse Address Resolution Protocol). At the transport layer used UDP (User Datagram Protocol) [5] other than TCP. For a while the discussion will be limited to the working principle of the IP protocols TCP damn. This is because TCP / IP is the protocol most often used in network operation, is a complement to other protocols that help these networks work. It should be noted that in computer networks using TCP / IP is generally done by the top three layers of the operating system of the computer being used. Especially for computers that use UNIX has been available for network programming library so that we can develop your own program with direct access to TCP sockets are available. Maybe on the other opportunity will be explained further on how the TCP socket programming in UNIX that can be accessed using the C language
The working principle of the Internet Protocol (IP).
The function of the Internet Protocol can be simply explained as the workings of the post office on mail delivery process. We input a letter to the mailbox will be taken by the postman and then be sent through a random route, without the sender and the recipients know the traveling path of the letter. Also if we send two letters to the same address on the same day, not necessarily because it may be up to the same letter that one would take a different route with another letter. In addition, there is no guarantee that the letter would reach the hands of destination, unless we send them using registered mail.
Above principle is used by Internet Protocol, "the letter" above is known as a datagram. Internet protocol (IP) functions deliver a datagram from one computer to another without depending on the medium used kompunikasi. The data transport layer is cut into datagram-datagram that can be carried by IP. Each datagram is removed in a computer network and will find themselves automatically route to be taken to the destination computer. This is known as connectionless transmission. In other words, the computer sending the datagram did not know whether the datagram will arrive or not.
To help reach the destination computer, each computer in a TCP / IP must be given an IP address. IP address must be unique for each computer, but not be an obstacle when a computer has multiple IP addresses. IP addresses consist of 8 bytes of data that has a value of 0-255 which is often written in the form [xx.xx.xx.xx] (xx has a value from 0-255).
In the Internet Protocol header in addition to the IP address of the destination computer and the computer sending the datagram there are also some other information. This information includes the type of transport protocol layer is superimposed over IP. Shown in figure 2 there are two types of protocol at the transport layer are TCP and UDP. Other important information is the Time-To-Live (TTL) which determines how long the IP can live on the network. TTL value will be reduced by one if the IP through a computer. This is important mainly because the IP is removed in a computer network. If for some reason could not find the IP address of the destination with the IP TTL will die by itself when the TTL is zero. Besides, also each given identification IP forwarding so that together with the IP address sending computer data and the destination computer, each IP in the network is unique.
Especially for users of computer networks are the most important thing to understand it really is the concept of an IP address. Institutions that set the IP address is the Network Information Center (NIC) in the Department of Defense in the U.S. located at hostmaster@nic.ddn.mil. IP address setting is important, especially when the routing automatically. As an example of a computer network in amateur radio have a class that has the IP address address [44.xx.xx.xx]. Especially for amateur radio in Indonesia the IP address used is [44.132.xx.xx]. While writers in Canada have an IP address [44.135.84.22]. This can be seen clearly that the IP address in the amateur radio geographical nature. From writer-readable IP addresses that machines on a network 44 writers on the Internet, known sabagai AMPRNet (ampr.org). 135 signifies that the author was in Canada. 84 tells us that the author was in the city of Waterloo in Ontario province, while 22 is the engine number writer. With the concept of IP addresses, IP traveled route in the network computer can be done automatically. For example, if a computer on the Internet will send the IP [44.135.84.22], first released in the IP network will try to find a way to network 44.135.84, after the machines that connect the IP network 44.135.84 achieved will try to contact 22 machines in the network. All this is done automatically by the program.
Surely it is difficult for humans to remember so many IP addresses. For ease, developed the Domain Name System (DNS). For example, authors in AMPRNet machine with the IP address [44.135.84.22], the authors give the name (hostname) ve3.yc1dav.ampr.org. Seen that the hostname used writer is very specific and very easy to learn that the author was in AMPRNet of ampr.org said. The machine was located in Canada and the provinces of Ontario currently YC1DAV ve3 is a writer himself. Another example of the DNS is sun1.vlsi.waterloo.edu which is a Sun SPARC workstation (sun1) in the VLSI research group at the University of Waterloo, Canada (waterloo.edu) where the author's work and learn. It should be noted that the current NIC domain not given to Indonesia. Hopefully with the development of computer network TCP / IP in Indonesia there are times when we in Indonesia have asked for a separate domain for Indonesia.
The working principle of the Transmission Control Protocol (TCP)
Unlike the Internet Protocol (IP), TCP has the working principle of such "virtual circuit" on the telephone network. TCP is more concerned with know-how and reliability in data transmission between two computers in the network. TCP does not care what is done by IP, which is important is the communication link between two computers running well. In this case, the TCP setting out how to open links of communication, what kind of applications will be done in such communications (eg sending e-mail, file transfer etc.). In addition, it also detects and corrects data errors if any. TCP governs the whole process of connection between one computer to another computer within a computer network.
In contrast to the connectionless IP mechanisms that rely on TCP is connection-oriented mechanism of the relationship. In this case, the logical relationships to be built by TCP from one computer to another computer. Within the specified computer that is connected to send data or acknowledge that the relationship continues. If this can not be done then it can be assumed that the computer is in contact with us disorders and logical relationship may be terminated.
TCP multiplexing set of data sent / received by a computer. The identification of the TCP header allows the multiplexing performed. This allows a computer to do some logical TCP connection. Form of relationship is full duplex, this allows two computers talk to each other at the same time without having to take turns using the channels of communication. To overcome the saturation (congestion) on the communication channel, the TCP header has information about flow control.
It is quite important to understand the TCP port number is. Port number to determine the services performed by the application program over TCP. These numbers have been determined by the Network Information Center in the Request For Comment (RFC) 1010 [10]. As an example for the application File Transfer Protocol (FTP) over TCP transport layer used port number 20 and many more.
The working principle of the TCP based client-server principle. Server is a program on a computer that will passively listen (listen) port number specified in the TCP. 're Client is a program that actively opens a TCP connection to the server computer to request the services needed.
Working TCP state diagram shown in Figure 3. In the state diagram of figure 3, the client will actively open a connection (active open) by sending a SYN signal (SYN Sent state) to a destination server computer. If the server receives the SYN signal the server when it is in LISTEN state will send a signal SYN and the two computers (client & server) going to the ESTAB state. If no response from the destination computer, then the program will return to the state CLOSE. After the service performed has been completed then the client will send the wrong signals FIN and client computers will be in state FIN FIN WAIT until the signal is received from the server. On receipt of the FIN signal, the server to the state CLOSE WAIT until the connection is disconnected. Finally, both computers will be back on the state CLOSE.
Some examples of applications of the Internet
Many applications are possible using a family of TCP / IP. Typical applications are the electronic delivery of news, known as electronic mail (e-mail). It developed a protocol for Simple Mail Transfer Protocol (SMTP) [6]. The protocol sets out procedures for transmitting messages from a user on a computer to another using a unique address. For example, e-mail me at AMPRNet are:
yc1dav@ve3.yc1dav.ampr.org
which means that the author YC1DAV was in (at, @) ve3.yc1dav.ampr.org machine. Certainly at the time of delivery of news, the IP will do the conversion of hostnames to IP addresses ve3.yc1dav.ampr.org author [44.135.84.22] to then send the information to be included in the SMTP protocol TCP.
Another application is the remote login to a remote computer. This is done by using the Telnet facility [7] run over the TCP transport layer. To perform file transfers use File Transfer Protocol (FTP) [8] which is also run over TCP. With the growing complexity of the network, network management becomes crucial. Currently developed a special protocol to be used to manage the network as Simple Network Management Protocol (SNMP) [9]. There are many other applications that run on top of TCP, such as NNTP, etc. RSPF. Each application has a unique TCP port number.
One thing is quite interesting with the use of TCP / IP is the possibility to connect multiple computer networks using different communication media. In other words, the computer connected to the network using ARCnet, Ethernet, Token Ring, SKDP, amateur packet radio, etc.. can talk to each other without knowing each other that communication media that are used physically different. This makes it possible to easily form a Wide Area Network in Indonesia. Currently UNINET pioneered by colleagues from PUSILKOM-UI was faltering mainly because of the high cost that must be spent for communication. In addition, the protocol used in networks today is the UUCP UNINET which is basically a very simple protocol. It is not possible UNINET to do things that are possible only by the TCP / IP such as automated network management using SNMP and relationships as it is done using a connectionless IP.
To further clarify, it's good real world examples the authors put forward by the author in amateur packet radio network (AMPRNet) in Canada. Broadly speaking, computer network topology packet radio amateurs in Waterloo shown in Figure 4. Currently the network AMPRNet in Waterloo working on The frequency of 145.09MHz at 1200bps speed. We plan for upgrading the network TCP / IP available to the speed of 9600bps. In the picture's written some of the machines of friends and writers such as at.ve3euk.ampr.org home.ve3rks.ampr.org.
Here we have a gateway at.ve3uow.ampr.org's University of Waterloo - Amateur Radio Club (ARC UoW), which the authors are also members, is the gateway connecting networks AMPRNet with Token Ring LAN PC network at the University of Waterloo. Through a gateway that is in a Token Ring network, the IP sent by the machine in AMPRNet may be associated with the Unix machines in the Ethernet network at UoW or with other machines on the Internet. There is not much between AMPRNet and Internet gateways that operate in the world today. It can be seen in the previous article writers on the author's experience working in amateur packet radio networks abroad.
At Waterloo we use sunee.waterloo.edu AMPRNet and watserv1.waterloo.edu as domain name server (DNS). In other words, using the protocol UDP / IP machines AMPRNet at Waterloo if it will relate to other machines on the Internet that hostnamenya AMPRNet or known to ask for the IP address of the destination machine to the DNS. All this is done automatically without the need for machine operators know the process occurs.
With the technology in the world of amateur radio amateur packet radio. The possibility of developing low-cost WAN in Indonesia became possible. UNINET AMPRNet because it is not possible using amateur packet radio is not familiar with UUCP. Even if forced amateur radio must develop the necessary software from scratch. The use of TCP / IP will make it easier internetwoking with various networks like AMPRNet thereby opening the possibility of developing cost WAN easy, but with a much better facility than the UUCP.
Cover
General working principle of using the family computer network protocol TCP / IP has been described in outline. Some examples of usage and the possibility to form a WAN using TCP / IP has been described. Some articles / books that might provide a fairly in-depth information about the working principle of the network using TCP / IP can be obtained in RFC 1122 [12] and RFC 1123 [13]. Copies of RFCs can be obtained from the Network Information Center (NIC) located at:
DDN Network Information Center
SRI International
333 Ravenswood Avenue
Menlo Park, CA 94025
U.S.A.
tel: 800-235-3155
For those of us who are overseas, simply copy the RFC can we get for free by doing an FTP to NIC.DDN.MIL. Several copies of the RFC in the form of a compressed file on a diskette has the writer sent to Indonesia. Currently the files in a diskette containing the RFC on TCP / IP, the program KA9Q TCP / IP and source code that I use for my work in the network AMPRNet, most likely can be obtained from Dr. Kusmayanto Kadiman (chairman PIKSI-ITB), Ir. A. Mas'ud (PAU Microelectronics ITB), Dr. S. Nasserie (Department of Electrical Engineering ITB), magazine editor and ITB Electron Amateur Radio Club. The author hopes this article will give general overview of computer networks TCP / IP and the possibility of its development in Indonesia.
REFERENCES
[1] J. Postel, "RFC 791: Internet Protocol (IP)," Internet Network Working Group, September 1981.
[2] J. Postel, "RFC 793: Transmission Control Protocol," Internet Network Working Group, September 1981.
[3] J. Postel, "RFC 792: Internet Control Message Protocol," Internet Network Working Group, September 1981.
[4] D.C. Plummer, "RFC 826: An Ethernet Address Resolution Protocol," Internet Network Working Group, November 1982.
[5] J. Postel, "RFC 768: User Datagram Protocol," Internet Network Working Group, August 1980.
[6] J. Postel, "RFC 821: Simple Mail Transfer Protocol," Internet Network Working Group, August 1982.
[7] J. Postel and J. Reynolds, "RFC 854: Telnet Protocol Specification," Internet Network Working Group, May 1983.
[8] J. Postel and J. Reynolds, "RFC 959: File Transfer Protocol (FTP)," Internet Network Working Group, October 1985.
[9] J. Case, M. Fedor, M. Schoffstall and C. Davin, "RFC 1098: A Simple Network Management Protocol," Internet Network Working Group, April 1989.
[10] J. Reynolds and J. Postel, "RFC 1010: Assigned Numbers," Internet Network Working Group, May 1987.
[12] R. Braden, "RFC 1122: Requirements for Internet Hosts - Communication Layers," Internet Network Working Group, October 1989.
[13] R. Barden, "RFC 1123: Requirements for Internet Hosts - Application and Support," Internet Network Working Group, October 1989.
DESCRIPTION OF FIGURES
Figure 1 The seven layer protocol used in a computer network in accordance with recommendations issued by the OSI / ISO.
Figure 2 family of protocols in computer networks using TCP / IP. It appears that in addition to TCP / IP is also used some of the additional protocol. It should be noted that the protocol presented above is only a part of the protocol known.
Figure 3 State diagram simply of the Transmission Control Protocol (TCP). The principle used in client-server interaction, two computers using TCP.
Figure 4 Example of network topology AMPRNet in Waterloo, Canada linked via at.ve3uow.ampr.org to Token Ring PC network and then through the Ethernet network and the machine watmath.waterloo.edu related to the Internet computer network.
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