TCP / IP protocol layering Comments
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TCP / IP and ISO / OSI
ISO / OSI model, i.e., Open Systems Interconnection Reference Model (Open System Interconnection Reference Model), the International Organization for Standardization (ISO) made of a variety of computer trying to make a standard framework for the interconnect network in the world, referred to as OSI .
TCP / IP protocol model (Transmission Control Protocol / Internet Protocol) , consists of a series of network protocols constitute the foundation of the Internet is the Internet's core protocols, through 20 years of development has become more mature, and is widely used in local area networks and wide area networks, It has become the de facto international standard. TCP / IP protocol suite is a combination of a plurality of protocols on different levels of a group, generally considered to be a four-layer protocol system, and corresponds to the OSI seven-layer model.
TCP / IP hierarchical model
- Application layer
The application layer determines the communication activities of providing application services to users. || The application layer is responsible for handling specific application details.
TCP / IP protocol suite stored within a variety of common application services. For example, FTP (File Transfer Protocol, File Transfer Protocol) and DNS (Domain Name System, the domain name system) service is one of the two categories. Also in the HTTP protocol layer.
- Transport Layer
Transport upper application layer, data transmission is provided between the two computers in a network connection.
In a different transport layer protocols of two properties: TCP (Transmission Control Protocol, Transmission Control Protocol) and UDP (User Data Protocol, User Datagram Protocol).
Main-end communications for application on both hosts. In the TCP / IP protocol suite, there are two different transmission protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
TCP provides a highly reliable data communication to two hosts. All it does it comprises the application to the appropriate data into small blocks to the network layer below, acknowledgment packets received, provided the final confirmation packet transmission timeout clock or the like. Since the end of the transport layer provides a highly reliable communication, the application layer can ignore all these details. In order to provide reliable service, TCP retransmission timeout mechanism uses a transmission and reception end acknowledgment packet or the like.
UDP was the application layer provides a very simple service. It just transmitted packet is called datagrams from one host to another host, but does not guarantee that the packets reach the other end. It refers to a datagram one information unit (e.g., a certain number of bytes of information specified by the sender) transmitted from the sender to the recipient. Any necessary reliability of the UDP protocol layer must be provided by the application.
- Network layer
Network layer for processing data packets flowing on the network. Packet is a minimum data unit transmission network. This layer defines how to reach the other side of a path through a computer (a so-called transmission line), and transmits the data packets to each other.
When transmission by a plurality of computers or other network device between the computer, the network layer is to choose the role of a transmission path in many options.
Also referred to as Internet layer (Internet layer as a first drawing), processes the packet in the network, for example, routing of the packet. In the TCP / IP protocol suite, network layer protocols such as IP protocol (Internet Protocol), ICMP protocol (Internet Internet Control Message Protocol), and IGMP protocol (Internet Group Management Protocol).
IP is a network layer protocol, provides an unreliable service, it is only as fast as the packet from the source node to the destination node, but does not provide any guarantee reliability. It is also used by TCP and UDP. Each TCP and UDP data are transmitted via the Internet in the terminal and IP layers of each intermediate router.
ICMP protocol IP protocol is a subsidiary. IP layer it with other hosts or routers to exchange error messages and other important information.
IGMP is the Internet Group Management Protocol. It is used to a UDP datagram multicasting to multiple hosts.
- Link layer
Hardware processing section is connected to the network. It comprises a control operating system, hardware, device drivers, NIC (Network Interface Card, a network adapter, i.e. NIC), and the visible portion of the optical fiber and other physical (including all further connected to transmission media, etc.). It is visible on the hardware within the scope of the link layer.
Also known as data link layer or the network interface layer (in the figure as a first network interface layer and hardware layer), typically includes an operating system, device drivers and a corresponding computer network interface card. They are processed together with details of the physical interface cable (or any other transmission medium) is. ARP (Address Resolution Protocol) and the RARP (Reverse Address Resolution Protocol) protocol is a certain special network interface (such as Ethernet and Token Ring) used for converting the IP layer address and network interface layer used.
Package and sub-data by
When an application using TCP to transfer data, the data is sent to the protocol stack, through each layer then one by one until it is fed into the network as a series of bit streams. Wherein each layer of the received data must add header information (sometimes increase trailer information), the process shown in FIG.
TCP IP data unit is referred to pass TCP segment or segments referred to as TCP (TCP segment); UDP data consistent with the TCP data. The only difference is the UDP IP passed information unit called a UDP datagram (UDP datagram), and UDP header length is 8 bytes. IP network interface layer to pass data units called IP datagram (IP datagram). Called a frame (Frame) Ethernet transmission of a bitstream.
When the destination host receives an Ethernet data frame, the data from the protocol stack begins to increase, at the same time remove the packet header plus the protocol layers from substrates. Cassette have to check each protocol packet protocol identification in the header to determine the upper layer protocol of the received data. This process is called demultiplexing (Demultiplexing). Protocol is unpacked by the destination port number, source IP address and source port number.
Other related concepts
- The port number
Servers are generally identified by the well-known port number. For example, for each TCP / IP is implemented, the TCP port number 21 is the FTP server, each server Telnet TCP port numbers are 23, each of the TFTP (Trivial File Transfer Protocol) server UDP port numbers are 69. Service of any TCP / IP implementations are provided with well-known port numbers between 1 to 1023. These well-known port numbers are managed by the Internet Assigned Numbers Authority (Internet Assigned Numbers Authority, IANA). Known port number is between 1 to 255; port number from 256 to 1023 are usually occupied by the Unix system, a Unix to provide a specific service; 1024 to 5000 for the port number assigned to the client ephemeral port number; greater than port number 5000 is reserved for other servers.
- DNS
DNS is an acronym for Computer Domain Name System (Domain Name System or Domain Name Service), which is by the parser and domain name servers. It refers to a domain name server in the network stores the corresponding IP address and the domain name, the domain name and having to convert to IP addresses of all hosts function server.
TCP / IP communications transport stream
When network communication using TCP / IP protocol family, it will be communicated with each other through a hierarchical order. Go down from the transmitting side application layer, the receiving end to go up to the application layer.
We use HTTP To illustrate, first as the sender's client sends an HTTP request to a Web page to see the application layer (HTTP protocol).
Next, in order to facilitate transport, the transport layer (TCP protocol) received from the data at the application layer (HTTP request message) is divided, and marked with the tag ID and the port number forwarded to the network layer in each packet.
Forwarded to the link layer is the network layer (IP protocol), increase as the communication destination MAC address. Thus, the communication request sent to the network to complete the preparation.
Receiving end server receiving the data link layer, sequentially transmitted to the upper layer until the application layer. When the transmission to the application layer, can be considered actually received by the client sent from the HTTP request.
When transmission data is transmitted between the terminal layers, each layer passes must be marked with a header information of the layer belongs. Conversely, at the receiving end when transmission of the data layers, the first unit will erase the corresponding elapsed time of each layer.
This information is packaged data is called encapsulation approach (encapsulate).
Responsible for IP transport protocol
By sub-level, IP (Internet Protocol) Internet protocol at the network layer. Internet Protocol The name may sound a bit exaggerated, but the fact is the case, because almost all use of the network system will be used IP protocol. TCP / IP protocol suite IP refers to the Internet Protocol, protocol names accounted for half position, its importance is evident. Some people will "IP" and "IP address" confused, "IP" is actually the name of a protocol.
An IP protocol is to transmit various data packets to each other. And to ensure that there is indeed sent to the other party, you will need to meet all kinds of conditions. Two of the important conditions is the IP address and MAC address (Media Access Control Address).
Indicates the IP address is assigned to the node address, MAC address refers to a fixed address belongs to the network card. IP address and MAC address pair. IP address conversion, but does not substantially change the MAC address.
Using the ARP protocol to communicate with the MAC address
Communication between the MAC address-dependent IP. On the network, the communication of both sides in the same local area network (LAN) is very small, usually after multiple computers and network devices to connect to each other transit. During the transfer, the MAC address will use the next relay device to search for a next relay destination. At this time, we will use ARP protocol (Address Resolution Protocol). ARP is a protocol for address resolution, it can be isolated anti MAC address corresponding to the IP address of the communication party.
text
TCP / IP and ISO / OSI
ISO / OSI model, i.e., Open Systems Interconnection Reference Model (Open System Interconnection Reference Model), the International Organization for Standardization (ISO) made of a variety of computer trying to make a standard framework for the interconnect network in the world, referred to as OSI .
TCP / IP protocol model (Transmission Control Protocol / Internet Protocol) , consists of a series of network protocols constitute the foundation of the Internet is the Internet's core protocols, through 20 years of development has become more mature, and is widely used in local area networks and wide area networks, It has become the de facto international standard. TCP / IP protocol suite is a combination of a plurality of protocols on different levels of a group, generally considered to be a four-layer protocol system, and corresponds to the OSI seven-layer model.
TCP / IP hierarchical model
- Application layer
The application layer determines the communication activities of providing application services to users. || The application layer is responsible for handling specific application details.
TCP / IP protocol suite stored within a variety of common application services. For example, FTP (File Transfer Protocol, File Transfer Protocol) and DNS (Domain Name System, the domain name system) service is one of the two categories. Also in the HTTP protocol layer.
- Transport Layer
Transport upper application layer, data transmission is provided between the two computers in a network connection.
In a different transport layer protocols of two properties: TCP (Transmission Control Protocol, Transmission Control Protocol) and UDP (User Data Protocol, User Datagram Protocol).
Main-end communications for application on both hosts. In the TCP / IP protocol suite, there are two different transmission protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
TCP provides a highly reliable data communication to two hosts. All it does it comprises the application to the appropriate data into small blocks to the network layer below, acknowledgment packets received, provided the final confirmation packet transmission timeout clock or the like. Since the end of the transport layer provides a highly reliable communication, the application layer can ignore all these details. In order to provide reliable service, TCP retransmission timeout mechanism uses a transmission and reception end acknowledgment packet or the like.
UDP was the application layer provides a very simple service. It just transmitted packet is called datagrams from one host to another host, but does not guarantee that the packets reach the other end. It refers to a datagram one information unit (e.g., a certain number of bytes of information specified by the sender) transmitted from the sender to the recipient. Any necessary reliability of the UDP protocol layer must be provided by the application.
- Network layer
Network layer for processing data packets flowing on the network. Packet is a minimum data unit transmission network. This layer defines how to reach the other side of a path through a computer (a so-called transmission line), and transmits the data packets to each other.
When transmission by a plurality of computers or other network device between the computer, the network layer is to choose the role of a transmission path in many options.
Also referred to as Internet layer (Internet layer as a first drawing), processes the packet in the network, for example, routing of the packet. In the TCP / IP protocol suite, network layer protocols such as IP protocol (Internet Protocol), ICMP protocol (Internet Internet Control Message Protocol), and IGMP protocol (Internet Group Management Protocol).
IP is a network layer protocol, provides an unreliable service, it is only as fast as the packet from the source node to the destination node, but does not provide any guarantee reliability. It is also used by TCP and UDP. Each TCP and UDP data are transmitted via the Internet in the terminal and IP layers of each intermediate router.
ICMP protocol IP protocol is a subsidiary. IP layer it with other hosts or routers to exchange error messages and other important information.
IGMP is the Internet Group Management Protocol. It is used to a UDP datagram multicasting to multiple hosts.
- Link layer
Hardware processing section is connected to the network. It comprises a control operating system, hardware, device drivers, NIC (Network Interface Card, a network adapter, i.e. NIC), and the visible portion of the optical fiber and other physical (including all further connected to transmission media, etc.). It is visible on the hardware within the scope of the link layer.
Also known as data link layer or the network interface layer (in the figure as a first network interface layer and hardware layer), typically includes an operating system, device drivers and a corresponding computer network interface card. They are processed together with details of the physical interface cable (or any other transmission medium) is. ARP (Address Resolution Protocol) and the RARP (Reverse Address Resolution Protocol) protocol is a certain special network interface (such as Ethernet and Token Ring) used for converting the IP layer address and network interface layer used.
Package and sub-data by
When an application using TCP to transfer data, the data is sent to the protocol stack, through each layer then one by one until it is fed into the network as a series of bit streams. Wherein each layer of the received data must add header information (sometimes increase trailer information), the process shown in FIG.
TCP IP data unit is referred to pass TCP segment or segments referred to as TCP (TCP segment); UDP data consistent with the TCP data. The only difference is the UDP IP passed information unit called a UDP datagram (UDP datagram), and UDP header length is 8 bytes. IP network interface layer to pass data units called IP datagram (IP datagram). Called a frame (Frame) Ethernet transmission of a bitstream.
When the destination host receives an Ethernet data frame, the data from the protocol stack begins to increase, at the same time remove the packet header plus the protocol layers from substrates. Cassette have to check each protocol packet protocol identification in the header to determine the upper layer protocol of the received data. This process is called demultiplexing (Demultiplexing). Protocol is unpacked by the destination port number, source IP address and source port number.
Other related concepts
- The port number
Servers are generally identified by the well-known port number. For example, for each TCP / IP is implemented, the TCP port number 21 is the FTP server, each server Telnet TCP port numbers are 23, each of the TFTP (Trivial File Transfer Protocol) server UDP port numbers are 69. Service of any TCP / IP implementations are provided with well-known port numbers between 1 to 1023. These well-known port numbers are managed by the Internet Assigned Numbers Authority (Internet Assigned Numbers Authority, IANA). Known port number is between 1 to 255; port number from 256 to 1023 are usually occupied by the Unix system, a Unix to provide a specific service; 1024 to 5000 for the port number assigned to the client ephemeral port number; greater than port number 5000 is reserved for other servers.
- DNS
DNS is an acronym for Computer Domain Name System (Domain Name System or Domain Name Service), which is by the parser and domain name servers. It refers to a domain name server in the network stores the corresponding IP address and the domain name, the domain name and having to convert to IP addresses of all hosts function server.
TCP / IP communications transport stream
When network communication using TCP / IP protocol family, it will be communicated with each other through a hierarchical order. Go down from the transmitting side application layer, the receiving end to go up to the application layer.
We use HTTP To illustrate, first as the sender's client sends an HTTP request to a Web page to see the application layer (HTTP protocol).
Next, in order to facilitate transport, the transport layer (TCP protocol) received from the data at the application layer (HTTP request message) is divided, and marked with the tag ID and the port number forwarded to the network layer in each packet.
Forwarded to the link layer is the network layer (IP protocol), increase as the communication destination MAC address. Thus, the communication request sent to the network to complete the preparation.
Receiving end server receiving the data link layer, sequentially transmitted to the upper layer until the application layer. When the transmission to the application layer, can be considered actually received by the client sent from the HTTP request.
When transmission data is transmitted between the terminal layers, each layer passes must be marked with a header information of the layer belongs. Conversely, at the receiving end when transmission of the data layers, the first unit will erase the corresponding elapsed time of each layer.
This information is packaged data is called encapsulation approach (encapsulate).
Responsible for IP transport protocol
By sub-level, IP (Internet Protocol) Internet protocol at the network layer. Internet Protocol The name may sound a bit exaggerated, but the fact is the case, because almost all use of the network system will be used IP protocol. TCP / IP protocol suite IP refers to the Internet Protocol, protocol names accounted for half position, its importance is evident. Some people will "IP" and "IP address" confused, "IP" is actually the name of a protocol.
An IP protocol is to transmit various data packets to each other. And to ensure that there is indeed sent to the other party, you will need to meet all kinds of conditions. Two of the important conditions is the IP address and MAC address (Media Access Control Address).
Indicates the IP address is assigned to the node address, MAC address refers to a fixed address belongs to the network card. IP address and MAC address pair. IP address conversion, but does not substantially change the MAC address.
Using the ARP protocol to communicate with the MAC address
Communication between the MAC address-dependent IP. On the network, the communication of both sides in the same local area network (LAN) is very small, usually after multiple computers and network devices to connect to each other transit. During the transfer, the MAC address will use the next relay device to search for a next relay destination. At this time, we will use ARP protocol (Address Resolution Protocol). ARP is a protocol for address resolution, it can be isolated anti MAC address corresponding to the IP address of the communication party.