Start slowly with some rough understanding of computer networks, no longer dazzled before.
address:
Communication transmission, the transmitter and receiver may be considered as the main communication. They can be identified by the information out as a source of "address". When people use the phone, the phone number is equivalent to "address when people choose to write a letter, mailing address, plus the name is equivalent to" address. "
Among the real-life "address" it is easier to understand, but in computer communications among concepts such address appears to be more complicated. Because the actual network communication among the address of each layer of the protocol used are different.
Address is unique, the address must be a clear indication of a principal object in the same communication network, the communication is not allowed in the same address exist two main body.
Address hierarchy:
In the case where the total number of addresses is not a lot, with the unique address can locate the body communicate with each other.
However, when the total number of addresses growing for a long time, how to efficiently find out the target address of the communication will be an important issue. For this reason it was discovered that in addition to address unique needs are hierarchical. In fact, in the process of using the telephone and mail communication, already have a hierarchical address this concept. For example, the phone number including the country code and the national area code, mailing address include the country name, province name, city name and region names. It was with this level of classification in order to locate a particular address more quickly.
MAC address (a physical layer, the data is converted to a voltage and 0,1 pulsed light transmitted to the physical transmission medium, the address used to realize transmission between devices connected to each other directly. This is called address MAC address, also known as physical address or hardware address) and IP address identifies a communication when the same subject though are unique, but among them only the IP addresses are hierarchical.
MAC address "specified by the manufacturer of the device for each card separately, people can manufacturer identification number, manufacturer part number and product inside a serial number to ensure uniqueness of the MAC address, however, one can not determine which manufacturer which which places the card is used.
Although the MAC address of manufacturer identification number, product number and a serial number and other information has also to some extent a certain hierarchy, but to find the address and did not play any role, it is not counted as hierarchical address. For this reason, although the MAC address is the real address of the ultimate responsible for communication, but in the actual process of addressing, IP addresses, an essential part.
Then the IP address is how to achieve a layered it? On the one hand, IP address consists of a network ID and a host ID. Different IP addresses even if the main communication if the number of different hosts, the same network number, indicating that they are on the same network segment. Typically, a network of host at the same department also belong to the same group or organization. On the other hand, the same number of hosts in the network are more focused on the organizational structure, provider type and geographical distribution, but also brought great convenience for IP addressing. This is also the reason why the IP address has a hierarchical nature.
Components of the network:
Data link communication medium:
It refers to a computer network and a computer connected to the computer network of. Then the computer between reality and how is it connected?
Interconnected between the computer through a cable. Cables can be divided into many, including twisted-pair cable, fiber optic cable, coaxial cable, serial cable and the like. The data link "Selection of different cable types are not the same, while the medium itself may be divided into different types of radio, microwave and other electromagnetic waves.
Transmission rate and throughput:
During data transmission, the speed of data flow between two physical devices called a transmission rate. Units of bps (Bits Per Second, the number of bits per second). Strictly speaking, the flow rate of the various transmission media signals is constant. Thus, even if the transmission rate of the data link is not the same, the transmission speed is not the case unsteadiness occurs. It means a high transmission rate is not how fast the speed of the flow of data units, but the amount of data transmitted per unit time number.
With our lives in road traffic, for example, low speed data link would not make a lot less like the lane while cars passing situations. In contrast, high-speed data link is equivalent to multiple lanes, allowing more time the vehicle is traveling on the road. Also referred to as the bandwidth of the transmission rate (Bandwidth).
The stronger the greater the bandwidth network transmission capacity.
Furthermore, the actual transfer rate between the host is called throughput. Which is the same bandwidth units are bps (Bits Per Second). The word is not only a measure of bandwidth, throughput, but also a measure of CPU processing capability of the host, the degree of congestion of the network.
NIC:
Any computer connecting to the network, you must use the card (called the network interface card). Township network interface card (NIC) sometimes called network adapters, network cards, LAN cards.
Recently, many have joined the catalog parameter "built-in LAN port", indicating that more and more computers in the factory setting to have the Ethernet (Ethernet) 1000BASE-T or 100BASE-TX port. "
Repeater:
A first layer of the OSI model - a network device to extend the physical level; wave passed over by the cable or optical signals, via a repeater and amplified and then passed to a waveform adjusting cable twenty-one
Under normal circumstances, both ends of the repeater is connected to the same communication medium, but some repeater may also work to complete the transfer between different media. For example, the adjustment signal between the coaxial cable and fiber optic cable. However, in this case, the repeater can simply replace the signal charge of between 0 and 1 bit stream, it is not responsible for determining whether the data has an error. Meanwhile, it is responsible for converting electrical signals to optical signals, and therefore can not be forwarded between different transmission speeds medium.
Performed by the network relay extension, which distance is not unlimited expansion. For example, up to four repeaters may be connected to a 10Mbps Ethernet segment, and a maximum of 100Mbps Ethernet is connected two repeaters.
Some repeaters can provide multiple port services. This is referred to as a repeater or hub repeater hub.
Thus, the hub "can also be seen as a multiport repeater, each port can become a repeater.
Gateway:
Gateway is the OSI reference model for data from the application layer and the transport layer to convert forwarding device. Responsible for forwarding protocol conversion and data.
It is the transport layer and processing the data above, but is also responsible for forwarding data gateway only converts data, which would normally use a presentation layer or application layer gateways translate between the two protocols can not communicate directly, and ultimately communication between the two.
A very typical example is the conversion between the Internet service e-mail and mobile phone messages. Mobile e-mail can sometimes be incompatible with the Internet e-mail, since they are different from each other in the presentation layer and application layer "e-mail protocol" caused.
So, why even between computers and mobile phones to the Internet can send each other e-mail it? Set up a gateway between the Internet and mobile phones. The gateway is responsible for a variety of protocols has been read, one by one they reasonable conversion, and then forwards corresponding data out. As a result, even if the application is between different e-mail protocols, computers and mobile phones can also send messages to each other.