Computers.. These “creatures” appeared on our planet relatively recently, and for many years they have been gathering thousands of people around them, attracting them with their capabilities. Someone is playing computer games, someone writes articles on them, and sometimes they can serve as your second TV or information storage device. While using your computer, have you ever asked yourself, “How the hell does this work?”? Even if they asked, they probably didn’t answer it, going online and wasting hours of their time. Actually, that's what I'm here for. I'll tell you briefly what exactly is in your computer and how it works.
Part 6. Network card
Probably, if it weren’t for today’s tendency to get all the information on the Internet, as well as use it for communication and playing games together (and a thousand other possibilities, to be honest), I would not have mentioned the network card. But almost the entire planet has now been taken over by the Internet, and now not a single computer can do without a network card. That is why I simply have to remind you of the existence of such a card as a network card.
Do you use a laptop? Then this article is just for your information, because now all laptop motherboards have a network card built into them. And not only in order to connect a patch cord (a wire consisting of 8 multi-colored fibers. It also has a latch), but also in order to be able to connect to the wireless Internet. Like the two previous cards, the network card looks like a small piece of the motherboard, filled with the same chips.
LAN card is very similar to the human mouth: it is the mouth that allows us to communicate with other people, and for this we do not have to connect to the interlocutor with some kind of wire. Because there are so many different channels inside. It is with the help of a network card that you can connect to the router using a wire, and if the card has wireless adapter- you can do it without wires.
Let's imagine that in your motherboard The network card is not integrated. Still, anything is possible, and it won’t hurt for overall development.
What does a network card consist of?
1. Processor or chip. A network card has a processor only if the card is needed for a server and not a desktop computer. Alas, unlike sound and video cards, ordinary network cards do not have their own processor, and therefore turn to the central one, and it, in turn, does its job: transmits frames from random access memory computer to the network. And in the opposite direction too.
2. RJ-45 connector. Designed for a patch cord that can come either from a workgroup switch (a thing that unites all computers in one office of some large company, for example), or from a router (in very small networks, like at my home).
3. Slot for BootRom. There is not always. What is this? You know, sometimes information in some companies is so confidential and protected that ordinary computers are simply not equipped with hard drives. BootRom, in turn, is a thing that helps connect to the server’s hard drive and allow to a regular computer work with him. This chip contains a code that allows you to connect to the network even without a hard drive.
Buying a network card
As a matter of fact, the purchase of a network card is justified by only one nuance: if the motherboard fails, then everything built into it will also fail. Spending once on separate equipment, on all the boards I listed, will reduce costs in the distant future. It is important.
1. Manufacturer. Look at it first, since the characteristics of the cards are always very similar, and choosing hardware based on one or more numbers simply won’t work. From good producers we can highlight D-Link, TP-Link and Cisco. It is entirely possible to experiment and buy products from other manufacturers, but do so at your own peril and risk.
2. Data transfer rate. Although the characteristics are the same almost everywhere (10/100 Mbit/s), sometimes the card is designed for really fast work. In this case, its transmission speed will be 10/100/1000 Mbit/s. Only in this case you will have to use a patch cord of category 5e, no less.
3. BootROM port. You don't need it unless you are a member of a well protected corporate network. And if you are, then they will give you a computer already assembled, and this component will be there.
Actually, there is nothing more to see. Honestly, the question of choosing a network card is entirely up to your aesthetic pleasure. The best thing to do would be to choose the right manufacturer, and the rest will come on its own. Moreover, Internet speed, first of all, depends not on the network card, but on the provider that supplies the Internet to you.
In small home networks, try to install exactly the network card that allows you to connect to the wireless Internet, and easily install Wi-Fi throughout the house. For laptops that do not have a wireless Internet connection, you can buy a small USB adapter that costs no more than 1,000 rubles.
Stay tuned to the site for updates and read more about computers and their little secrets.
Network card for computer- This is part of the PC hardware configuration. This device will allow you to connect a personal computer or laptop to networks of any size and ensure interaction with them. Network card for computer, usually called an Ethernet card, also has alternative name– network interface cards (“network interface cards” or NIC), network adapter or LAN adapter.
Standard Components
Network card for computer At first it was one of the components of an add-on, which can be purchased and installed on a computer not immediately with all the components, but after some time when the need arises. But today it has become obvious that network card for computer becomes one of the standard components that are installed in the absolute number of all produced desktop computers, laptops and NET-books. Network cards are integrated into a large number of modern motherboards and other devices during the initial manufacturing process. If network card for computer was installed into the system during assembly system unit, then when connected to local network it will reveal itself by small flickering indicators located near the network connector on the back wall of the system unit.
Network Card Identification
Absolutely every one network card for computer must be unique and for all this it is routinely equipped with a so-called “media access control” address, or otherwise known as a MAC, which helps identify each computer transmitting data packets through the network. This address is a 48-bit digital-character sequence that is installed using the firmware method into the chip's read-only memory (ROM) soldered onto the network board. The first row is the 24 bits of the MAC address and is called the group unique identifier “organizationally unique identifier” or OUI. Typically the MAC address is tied to the manufacturer of the network card. Subsequently, it can be replaced with another using MAC spoofing technology.
OSI model
The network card operates mutually at two levels of the open systems interaction model or another OSI. The first level, as a rule, is the physical level, which quite naturally determines the fact that network card for computer can provide physical access to the network. A network card for a computer can also operate at the second level of the OSI model, which is called the data link layer and is responsible for addressing. The main task of addressing using these two layers is to encode the MAC address into the data packets sent by each network card on any computer.
Types of network cards
Today, network cards can connect their computers both via a cable (physical) connection and via a wireless interface. When connecting via cable, a standard network port with an RJ-45 connector is usually used. A wireless network connection does not require the use of any physical ports or interfaces.
Characteristics and capabilities of network cards
Both types of network cards, wired and wireless, currently allow approximately the same data transfer speed. It typically ranges from 10 megabits per second to 1000 megabits per second (Mbps), depending on the manufacturer and model. Also, network card for computer serves to connect to the Internet, again via network protocols. , You can find out by following the link.
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Let's touch on a topic like the network card of our computer. Let's start with the fact that network cards are different and may differ both in the range of tasks they solve and in form factor ( appearance). The network card is also often called (Ethernet controller, network or NIC (Network Interface Card) adapter).
First of all, let's divide network cards into two large groups:
- External network cards
- Built-in or integrated (onboard)
Let's start with the external ones. From the name itself it follows that network cards of this type are installed additionally into the computer (with a separate expansion card) or as another external device.
First, let's talk about PCI network maps The abbreviation stands for (Peripheral Component Interconnect) - the interconnection of peripheral components or - an input-output bus for connecting peripheral devices to. These cards are called that because they are installed in one of the PCI slots (connectors). Here they are, in fact:
The PCI interface itself has a peak throughput for the 32-bit version, operating at a frequency of 33.33 MHz at 133 MB/s, the connector voltage consumption is 3.3 or 5V. Serves for installing additional expansion cards into the computer (old video cards, modems, network adapters, TV tuners, various video capture and video conversion cards, etc.).
So, what network cards are installed there? And here are the most common dollars for five or six:
There are adapters of another type - Wi-Fi (for organizing wireless networks).
As you can see, the connection interface is the same (PCI), but the operating principle is different.
Now, due to the gradual “withering away” of this interface, form factor network cards are being produced “ PC Express 1X".
This applies to external network cards. There are also built-in (integrated into the motherboard) cards. You can determine the presence of a built-in network by looking at the back wall of the system unit.
Here we can visually observe the output of the integrated network card. One or more information LEDs are installed next to the twisted pair connector, which can be used to indicate the presence of a connection and the general activity of the network.
By the way, using these LEDs you can indirectly get an idea of the performance of the device. Let me explain my point: when the computer is turned on and the network cable (twisted pair) is connected to the card, the LED on it blinks, as they say, in time with the reception (transmission) of information data packets by the adapter to the network.
If the network adapter is not working, the behavior of the indicators may be as follows:
- None of the LEDs light up at all
- The LED is constantly "on" (not blinking)
- The indicator blinks, but absolutely monotonously. The period and amplitude of this “blinking” are the same throughout the entire time
So, take note of such moments. Everything is in the details! :)
From the markings we see that this is an RTL chip (from Realtek) with number 8211BL.
Notes e: built-in solutions, unfortunately, are not reliable. In our organization, for example, failures of integrated network cards happen regularly. I can’t say that often, but consistently. By the way, my work computer (bought half a year ago) literally burned out the network card the other day, which once again strengthened my opinion about the unreliability of the integrated components. I had to install an external one.
I want you to take a close look at the following photo:
Here we look inside the network card connector. Do you notice the difference? One connector (on the right in the photo) has four contact pads, and the other (on the left) has eight. Moreover, both cards are designed for network transmission speeds of 100 megabits per second.
What's the catch here? And he, in any case, is present here :) Let's remember what the twisted pair cable itself looks like, with the help of which we laid networks in one of our free lessons.
It is correctly called UTP cable (Unshielded Twisted Pair - unshielded twisted pair). The fact that it is twisted (twisted) we can clearly see from the photo above. Its individual conductors are twisted around each other to improve the noise immunity of the entire cable as a whole.
The designation “unshielded” means that there is no additional protective shield (braid) made of foil or metal over the veins. Again - for better cable protection. And “pair” because the conductors in the cable are twisted in pairs and according to color (white-orange - orange, white-green - green, white-brown - brown, white-blue - blue).
Now - the most important: to ensure data transmission over a network at a speed of 100 megabits per second, you do not need to use all four pairs (eight conductor cores), two pairs (four cores) are enough! Moreover, strictly defined numbers are used: first, second, third And sixth postings
Directly from the RJ-45 connector it looks like this:
According to the above, to ensure a speed of 100 megabits, we use “veins” numbered 1, 2, 3 and 6. Look at the figure above. These are two pairs: orange and green.
Note: Naturally, it is up to us to decide which cores to use when terminating the cable. The main thing to remember is that these should be the 1st, 2nd, 3rd and 6th conductor (for networks with a transmission speed of 100 megabits/s).
Now look again at the photo, which shows a close-up of the computer’s network card connectors. In the right image there are only four contact pads: the first, second, third, the next two are skipped and then... which one? That's right - sixth! :)
When are all eight sites used? In networks with transmission speeds of one Gibabit per second (and higher). That's where all the guides are network cable used to the fullest :)
So, for some reason you and I (or rather, I alone :)) “veered” away from the main topic. What other network cards are there? Let's look at an external adapter for a laptop based on the PCMCIA standard. This - external board extension, which is inserted into the corresponding slot.
PCMCIA stands for Personal Computer Memory Card International Association. Initially, the standard was developed for memory expansion cards. After some time, the specification was expanded and it became possible to use “PCMCIA” to connect various peripheral devices. As a rule, network cards, modems or hard drives are connected through it.
Imagine an unpleasant picture: your laptop (to the left three times) the card built into it has failed. What to do? The solution is in the photo below:
There are, however, other solutions that are suitable not only for mobile computers, but also for stationary ones. These are USB network cards.
They can be made in different ways, but the principle of their operation does not change. Here, for example, are two such devices in the photo below:
Or even like this, more like a flash drive :)
I was about to end the article here, but... changed my mind! :) I also wanted to tell you about this type of external network cards, such as server network cards, which are used in high-performance systems and are more advanced (compared to regular adapters) networking capabilities.
Typically they have standard interface connections - PCI (or its extended version - PCI-X). Here, for example, is a server network card " D-Link DFE-580TX».
As you can see, these are essentially four network adapters combined into one physical device. Each of the four network ports (cards) has its own own MAC address (a unique 12-digit physical identifier of any card or other network device). At the same time, the entire group of ports can be assigned one logical identifier (IP address). For operating system a group of such cards looks like one virtual card.
Note: MAC (Media Access Control) address is also often called a physical or hardware address (Hardware Address). For example: the MAC address of my network adapter at work is 00-1B-11-B3-C8-82. There cannot be two identical hardware addresses on a network. You can find it out by entering command line: ipconfig /all or such a wonderful team using the utility of the same name, like getmac. Getmac will show you all MAC addresses of all network devices installed on the computer.
Let's continue. Combining several cards into one becomes possible using the “Port Aggregation” technology (aggregation or port consolidation). Port aggregation means combining several network segments into one with greater performance. When several network ports form one virtual one, then it throughput(theoretically) equals the performance of an individual port multiplied by their number.
Server network cards can operate in two main modes. Let's take a closer look at them. Using the software that comes with cards of this class, you can configure each port as “active” (load balancing mode) or reserve any ports to ensure fault tolerance (recovery mode).
The network load sharing (distribution) mode evenly passes network traffic (data flow) through active segments, reducing the overall load on the adapter, and the recovery mode (in the event of a physical connection failure) ensures uninterrupted communication between the network card and the network.
What else is good about a server network card on a computer? Depending on its “sophistication” :) it can implement computational functions (counting and generating checksums data frames transmitted over the network) in hardware, without additional load.
On such adapters specialized LSIs are installed (Large Integrated Circuits), which take on a significant part of the work (collision detection, assembly and disassembly of data packets, checking frame checksums and retransmitting damaged packets). Thus, as we have already said, a significant part of the load is removed from the processor, which server system there's plenty to do anyway :)
Moreover, expensive server network cards have their own processor installed. Such cards show very good performance, as they can effectively cope even with heavy loads. The presence of its own processor allows you to install up to one megabyte on them. And this already transfers these products from the category of just network cards to the category of communication network processors.
It should also be noted that useful function, as self-healing drivers for such devices. What it is? For example, after a network failure, the adapter can independently decide to restart the network card driver, enable a network connection integrity check, or even forcefully disable the failed port.
Select a network card suitable for your computer. Types of network cards: wired and wireless. MAC address of the network card. Operating principle of wireless cards.
A network card is a special hardware configuration of a computer.
This device allows you to connect your computer to networks of any size and ensure its very productive interaction with them.
As conceived, the network card was one of those additional devices that could be purchased and installed on a computer not immediately, but, if necessary, after a certain time.
True, it is now clear that the network card has already become a standard component that is installed in the vast majority of all PCs sold - it is integrated into motherboards and other devices at the production stage.
Types of network cards
Now network cards allow you to connect computers to the network not only using a cable, but also via a wireless interface.
For a cable connection, a regular network port with an RJ-45 connector is used. For wireless connection No physical interfaces or ports are needed to the network.
Now both of these types of network cards allow you to develop almost equal information transfer speeds. It varies in the range of 10-1000 megabits/sec, depending on the model.
Identification
Every network card must be unique - for this purpose it is equipped with a special MAC (media access control) address, which allows identifying each computer that transmits data over the network.
This address is a 48-bit digital and symbolic sequence that is flashed into ROM, a permanent memory chip mounted on the network board. The first 24 bits of the MAC address are called the group unique identifier OUI (organization unique identifier).
Usually, MAC address tied to the manufacturer of the network adapter, but then it can be changed to another using “MAC spoofing” technology.
What principles underlie the operation of a wireless network card?
In the era of high technology and mobility wireless internet becomes especially relevant.
A small wireless network card connects a PC to the network without using the capabilities of a conventional Ethernet cable connection or mobile phone. wireless communication GPRS.
The wireless card can be used in different versions. For example, in laptops, a wireless module is immediately integrated into the motherboard.
Often in desktop computers the card is installed as an additional expansion card for one of the PCI slots.
The principle of operation of wireless network cards is very simple. Such a wireless modem is responsible for the continuity of transmission and reception of information from the network.
The wireless router receives data from the provider on an external port, which is then converted into a radio signal broadcast via an antenna.
The wireless network card receives this signal and immediately converts it into an electronic signal adapted for a PC.
In general, setting up a wireless card is no different from setting up a regular card, and even more so - there is no need for physical contact with it.
How should you choose a wireless network card?
If you have several computers located in different rooms of the office or home, and they all need an Internet connection, then you should consider creating a wireless network.
To receive and transmit data in such a network, you need to equip everyone present desktop computers wireless network cards.
When choosing a card, be sure to take into account the fact that there is now a fairly large assortment of similar wireless modules, but with a different connecting interface and different functionality.
First, you should read the instructions for your PC (motherboards) in order to clarify which expansion slots they are equipped with.
If finding instructions is difficult, then disconnect all cables located behind the system unit and remove sidebar, having previously unscrewed the screws securing it.
Check for free slots on the motherboard and specify what they are (AGP, PCI or PCI-Express).
Having decided on a free slot, you should choose a network card in the store with an interface that matches the free slot on your PC.
If there is no free slot on your PC or if you do not want to use it, you should select external type wireless modem to connect it to USB port computer.
If your future plans include connecting to a cable network, then try to choose a card that is equipped with an additional Ethernet network port.
Be sure to check whether the card you choose can support the speeds provided by the access point. It is also important to make sure that the network card supports the 802.11a, 802.11b, as well as 802.11g and 802.11n standards.
The wireless card should be carefully inserted onto the motherboard into a free slot, the side panel should be returned to its place, and then you can connect all the network and interface cables to the required connectors.
After this, you can begin to configure the wireless network card.
Also known as a network card, network adapter, Ethernet adapter, NIC (network interface controller) - peripheral device, allowing the computer to communicate with other devices on the network.
Based on physical implementation, network cards are divided into:
1.internal- separate cards inserted into a PCI, ISA or PCI-E slot
2.external, connecting via USB or PCMCIA interface, mainly used in laptops.
3.built into the motherboard
Purpose of the network card
- preparing data coming from a computer for transmission via a network cable;
- transferring data to another computer;
- control the flow of data between the computer and the cable.
- takes data from the cable and translates it into a form that is understandable central processor computer
Network Card Settings
- hardware interrupt request line number IRQ
- DMA channel number (if supported)
- base I/O address
- RAM memory base address (if used)
- support for auto-negotiation duplex/half-duplex standards, speed
- support for tagged VLAN packets (801.q) with the ability to filter packets of a given VLAN I
- WON (Wakeup on LAN) parameters
Mechanism
1.Data preparation
Before data can be sent to the network, the network adapter card must convert it from a form that the computer can understand into a form in which it can be transmitted over the network cable.
Inside the computer, data is transferred via buses. A bus is several conductors located parallel to each other. Since there are several lines, data bits are transmitted along them in blocks, and not sequentially.
Firstly personal computers IBM used 8-bit buses: they could transfer blocks of 8 bits of data. The IBM PC/AT has a 16-bit bus, which means it can transfer 16 bits at once. Majority modern computers already equipped with a 32-bit bus. It is often said that data on a computer bus is transmitted in parallel because 16 bits or 32 bits move parallel to each other.
In a network cable, data must travel as a stream of bits. This is said to be a sequential transmission because the bits follow each other.
The network adapter card accepts parallel data and organizes it for serial, bit-by-bit transmission. This process is completed by converting the computer's digital data into electrical and optical signals transmitted over network cables. The transceiver (receiver) is responsible for this conversion.
2.Network address
The network adapter board, in addition to converting data, must indicate its location, or address, so that it can be distinguished from other boards.
Network addresses are administered by a committee of the IEEE (Institute of Electrical and Electronics Engineers, Inc). This IEEE committee assigns a certain range of addresses to each network adapter card manufacturer. Each manufacturer then writes its unique network address into the board's ROM.
When receiving data from a computer and preparing it for transmission over a network cable, the network adapter card also performs other actions:
- The computer and the network adapter card must be connected to each other in order to transfer data (from the computer to the card). If the board can use direct memory access, the computer allocates some area of its memory to it.
- The network adapter card requests data from the computer.
- The computer bus transfers data from its memory to the network adapter board.
Often data arrives faster than the network adapter card can transmit it, so it is temporarily buffered.
3.Data transfer and management
Before sending data to the network, the network adapter board conducts an electronic dialogue with the receiving board, during which they “discuss”:
- maximum block size of transmitted data;
- the amount of data transmitted without confirmation of receipt;
- intervals between transmissions of data blocks;
- the interval during which an acknowledgment must be sent;
- the amount of data that each card can receive without buffer overflow;
- transmission speed.
If the new (more complex and faster) board has to communicate with the old (slower) board, then they must find a common transfer rate for both of them. The circuitry of modern network adapter cards allows them to accommodate the slow speed of older cards.
Each board notifies the other about its parameters, accepting “other people’s” parameters and adapting to them. Once all the details are determined, the boards begin communicating.
4.Setting options
For proper operation The network adapter board must have its parameters set correctly:
- interrupt number (IRQ);
- base address of the I/O port;
- memory base address;
- transceiver type.
Network adapter board parameters are set in software and they must match the settings specified on the board by jumpers or DIP switches. Additional information You can learn how to configure the board using switches from its documentation.
5.Interrupt number
Interrupt request lines are physical lines through which various devices(such as I/O ports, keyboard, disk drives, and network adapter cards) can send a service request to the microprocessor.
Interrupt request lines are built into the computer hardware and have different priority levels, allowing the processor to determine the most important request.
By sending a request to the computer, the network adapter board organizes an interrupt - an electrical signal that is sent to the computer's central processor. All devices in the computer must use different interrupt request lines, or interrupts (IRQ). The interrupt request line is set when configuring the device.
In most cases, network adapter cards use the IRQ3, IRQ5, IRQ10, or IRQ11 interrupt. If you have a choice, it is recommended to give preference to IRQ10, especially since this value is set by default in many systems. To determine which interrupt values are set by default on your system, use diagnostic software utilities.
6. Selecting a transceiver
The network adapter card may have additional parameters - these also need to be specified during setup. For example, some boards come with an external and built-in transceiver. You need to specify the transceiver that will be used.
Transceiver selection is often made using jumpers - small connectors that, by connecting two pins, determine which circuit will operate.
7.Network cables and connectors
By coordinating the interaction between the network cable and the computer, the network adapter card performs three important functions:
- organizes physical connection with cable;
- generates electrical or light signals transmitted via cable;
- follows certain rules governing access to the network cable.
Before you select the right network adapter card for your network, you need to determine the type of cable and connectors you will use.
Each cable type has different physical characteristics that the board must meet. Therefore, the network adapter card is designed to work with a specific type of cable (coaxial, twisted pair or fiber optic).
Some network adapter cards have multiple types of connectors. For example, there are boards whose connectors are suitable for thin and thick coaxial cables, or for twisted pair and thick coaxial cable.
If the network adapter board has more than one interface connector, each of them is selected either using jumpers or DIP switches located on the board itself, or programmatically. To configure correctly network card, study its documentation. Below are typical connectors that can be found on a network adapter board.
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