Network card hardware

What are the most basic components in the network? Not a vswitch or a vro, but a small but ubiquitous Nic. If the network adapter has nothing to do with you five years ago, but in today's Internet era, no matter whether surfing the internet or playing games online, you cannot do without the network adapter. What's more, even if you don't have to worry about it, most boards also integrate an onboard Nic for you. Therefore, for readers who want to enter the network door, first understanding the network card will make you more comfortable in various network applications.

　　I. MAIN FEATURES OF NICs

NetworkInterfaceCard (NIC), also known as a network adapter, is a device connecting a computer to a LAN. A network card is required to connect to a LAN, whether it is a common computer or a high-end server. If necessary, two or more NICs can be installed on one computer.

    Figure 1One 10/100 Mbps PCI Nic

When computers communicate with each other, data is transmitted in frames instead of streams. We can regard frame as a data packet, which not only contains data information, but also contains the data sending location, receiving location information and data validation information. An ENI consists of two layers of the OSI model: the physical layer and the data link layer. The physical layer defines the electrical and optical signals, line statuses, clock baselines, data encoding, and circuits required for data transmission and receiving, and provides standard interfaces to data link layer devices. The data link layer provides addressing mechanisms, data frame construction, data error check, transfer control, and standard data interfaces to the network layer.

Two main functions of the network adapter are as follows: first, the computer data is encapsulated into frames and data is sent to the network through the network cable (electromagnetic waves for wireless networks; the second is to receive frames transmitted by other devices on the network, recombine the frames into data, and send them to the computer. The network adapter can receive all signals transmitted over the network, but normally only accept frames and broadcast frames sent to the computer, and discard the remaining frames. Then, it is sent to the system CPU for further processing. When the computer sends data, the network adapter waits for the appropriate time to insert the group into the data stream. Whether the received system notifies the computer of the complete arrival of the message. If there is a problem, the recipient will be asked to resend the message.

　　2. Graphic Nic

Figure 2Graphical PCI Nic

Taking the most common PCI interface Nic as an example, a card consists of a PCB circuit board, a main chip, data mercury, and a golden finger (bus slot interface), bootrom, EEPROM, crystal oscillator, RJ45 interface, indicator light, fixed chip, and some diodes, resistance and capacitance. Next, let's take a look at the main components.

● Main chip

    Figure 3The most common 8139d Chip

The main control chip of the network card is the core component of the network card. The performance of a network card is good or bad, and the strength of the function is many, mainly depends on the quality of this chip. For example, the rtl8139c and rtl8139d launched by RealTek are slightly different in encapsulation. The former is 128pin.QFP/lqfp, while the latter is 100pin. Secondly, 8139c has more support for 93c56 than the latter, while 8139d is 93c46. However, 8139d is more powerful in terms of functionality, and it provides moreMulti-function and PCI-BridgeI/f Support, PCIMulti-function allows the rtl8139d chip and other functional chips (such as hardware modulation and demodulation chips) to work collaboratively on the same PCB to form different types of multi-function cards, among them, the role of 8139 is to identify the LAN signal or PCI bus signal; 8139d also enhances the power management function.

If the speed is determined by the speed of the main chip of the NIC, the common 10/100 M Adaptive Nic chip is RealTek.8139 series/810x series,Vt610 * series, Intel82550pm/82559 series, Broadcom44xx series, 3Com3c920 series, davicomDm9102, mxicMx98715 and so on.

Common 10/100/8254 M Adaptive Nic chips include Intel's * series, Broadcom's bcm57 ** series, and Marvell's 88e8001/88e8053/88e806 * series, realTek RTL8169S-32/64, RTL8110S-32/64 (LOM), rtl8169sb, rtl8110sb (LOM), rtl8168 (PCIExpress), rtl8111 (Lom, PCIExpress) series, via vt612 * series, and so on.

     Figure 4Vt6120 Gigabit chip of

Figure 5Marvell 88e8001 Gigabit Chip

It should be noted that the NIC chip also has the "soft and hardware", especially for Nic chips with motherboard board-mounted (LOM). What is the problem? As you know, Ethernet interfaces can be divided into the protocol layer and the physical layer.

The protocol layer is composedAccessA single module of the controller.

The physical layer consists of two parts:Layer, physical layer) and transmitter.

The common Nic chips integrate Mac and PHY into one chip. However, currently, many nanqiao chips on the Main Board contain Ethernet MAC control functions, but do not provide physical layer interfaces. Therefore, an external PHY chip is required to provide an Ethernet access channel. This type of PHY network chip is commonly known as the "soft Nic chip". The commonly used PHY function chips include rtl8201bl and vt6103.
 

    Figure 6Rtl8201blPhy Chip

"Soft network card" generally transfers the operation part of the network control chip to the processor or nanqiao chip to simplify the line design and reduce the cost, but it will occupy more system resources.

● Bootrom

Bootrom socket, also known as the diskless boot ROM interface, is used to construct a diskless workstation through the Remote Boot service. Remoteboot (RPL) allows you to use software on the server's hard disk to boot a workstation on the network instead of the workstation's hard disk. An RPL (remoteProgramThe ROM chip can be started without a disk.Rom chips are made for a specific type of network interface card and cannot be exchanged between them. A network interface card with RPL sends a broadcast of Boot Record requests (broadcasts), the server automatically establishes a connection to respond to it, and loads the MS-DOS boot file into the workstation's memory.
 

 Figure 7Bootrom socket and 93c46 in its centerEEPROM Chip

In addition, there is usually a 93c46, 93lc46 or 93c56 EEPROM chip in the bootrom slot Center (93c56 is 128 * 16bit EEPROM, while 93c46 is 64 * 16bit EEPROM ), it is equivalent to the BIOS of the NIC, which records the NIC chip supplier ID, subsystem supplier ID, Nic MAC address, Nic configurations, such as the PHY address on the bus and bootrom capacity, whether to enable content such as the bootrom boot system. The eeprom information of the motherboard Nic is generally integrated into the motherboard BIOS.

● LED indicator
 
  Figure 8

Generally, each Nic has more than one led (light)EmittingLEDs are used to indicate the different working states of the network card, so that we can check whether the network card works normally. Typical led indicators include link/Act, full, and power. Link/Act indicates the connection activity status, and full indicates whether full duplex (fullDuplex), while power is a power indicator (mainly used on a USB or PCMCIA Nic.

● Network wake-up Interface
 

    Figure 9Some Reserved interfaces of Wol are also visible to some NICs

Early NICs also had a dedicated 3-core Socket network wake-up (Wol) interface (pci2.1 standard Nic), wakeOnLAN (Network wake-up) provides the ability to remotely wake up computers. It is an advanced management alliance established by IBM and Intel in October 1996.ManageabilityAlliance) is a result that allows administrators to remotely wake up computers during non-work hours and enable them to automatically complete some management services, such as software updates or virus scans. It is also wiredForManagement Basic specification. The principle of network wake-up is that a management software package sends a magic-basedPacket standard wake-up frame. After receiving the wake-up frame, the network card can analyze it and determine whether the frame contains the MAC address of the network card. If the MAC address of the NIC is included, the computer system automatically enters the boot status.

Currently, mainstream independent NICs or motherboard onboard NICs comply with pci2.2 and later specifications. Therefore, you do not need this interface. To enable the network wake-up function, you only need to enable "Wake" in the BIOS of the motherboard.OnPCICard function.