Graphic network card hardware-what is the hardware and software network card, what is the meaning of the PHY, etc.

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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
Network cards are indispensable for surfing the internet or playing games online. What's more, even if you don't eat fireworks, most boards will also integrate an onboard network card for you. Therefore, readers who want to step into the network should first recognize
Network Card recognition will make you more comfortable with various network applications.
I. MAIN FEATURES OF NICs
Network Interface Card (NIC), also known as Network adapter, is a device connecting a computer and 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 1 A 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 data
Verification Information of the sending and receiving locations and data. 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 and line shapes required for data transmission and reception.
Formats, clock benchmarks, data encoding, and circuits, 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 standards for the network layer.
.
Two main functions of the network adapter are as follows: one is to encapsulate computer data into frames and send data to the network through a network cable (electromagnetic waves for wireless networks); the other is
Receives frames from other devices on the network, reassembles the frames into data, and sends them to the computer. The network adapter can receive all signals transmitted over the network, but normally only accept frames and
Play the frames 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 computer message received by the system is complete
If a problem occurs, the recipient is requested to resend the request.
2. Graphic Nic

Figure 2 graphic 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 3 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. Launched by common Realtek companies
For example, RTL8139C and RTL8139D are slightly different in encapsulation. The former is 128pin QFP/LQFP, and the latter is 100pin.
On the EEPROM, 8139C has more support for 93c56 than the latter, while 8139D is 93C46. However, in terms of functions, the 8139D is more powerful and provides more
PCI Multi-function and PCI-bridge I/F Support, PCI Multi-function allows the RTL8139D chip and other
Functional chips (such as hardware modulation and demodulation chips) are designed to work collaboratively on the same PCB Board to form different types of multi-function cards. Among them, 8139 of them are used to identify the LAN signal or PCI bus signal.
And the power management function is also enhanced.
If the speed is determined by the speed of the main chip of the NIC, the common 10/100 M Adaptive Nic chip includes the Realtek 8139 series.
/810X series, VIA VT610 * series, Intel 82550PM/82559 series, Broadcom 44xx series, 3COM 3C920 series,
Davicom DM9102, Mxic MX98715, etc.
Common 10/100/8254 M Adaptive Nic chips include Intel's * Series
Column, Broadcom BCM57 ** series, Marvell 88E8001/88E8053/88E806 * series, Realtek RTL8169S-
32/64, RTL8110S-32/64 (LOM), RTL8169SB, RTL8110SB (LOM), RTL8168 (PCI Express ),
RTL8111 (LOM, PCI Express) series, VIA VT612 * series and so on.

Figure 4 VT6120 Gigabit chip of

Figure 5 Marvell 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 implemented by a single module called the MAC (Media Access Layer) controller.
The Physical Layer consists of two parts: the Physical Layer and the 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 connection is required.
The PHY chip is used to provide Ethernet access channels. 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 6 RTL8201BL PHY 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) makes it possible to use software on the server hard disk to boot a workstation on the network instead of the workstation hard disk. A
RPL (Remote Program Load Remote initial Program loading) ROM chip can achieve diskless startup, each rpl rom chip is for a specific type of network interface card
They cannot be exchanged. The network interface card with RPL sends a broadcast (broadcasts) of the boot record request, the server automatically establishes a connection to respond to it, and loads the MS-
The DOS boot file is stored in the memory of the workstation.

Figure 7 BOOTROM socket and 93C46 EEPROM chip in its center
　
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*16 bit EEPROM), which is equivalent to the BIOS of the NIC, which records the ID of the supplier of the NIC chip, the ID of the subsystem supplier, and the ID of the NIC
MAC address and nic configurations, such as the PHY address on the bus, BOOTROM capacity, and whether to enable the BOOTROM boot system. General information about the eeprom of the board Nic on the motherboard
Integrated into the motherboard BIOS.
● LED indicator

Figure 8
　
Generally, each Nic has more than one LED (Light Emitting Diode) indicator, which indicates the different working states of the NIC for us to check
Check whether the NIC is working properly. Typical LED indicators include Link/Act, Full, and Power. Link/Act indicates the connection activity status. Full indicates whether the connection is Full.
(Full Duplex), while Power is a Power indicator (mainly used on a USB or PCMCIA Nic.
● Network wake-up Interface

Figure 9 reserved WOL interfaces on some NICs
　
Early NICs also had a dedicated 3-core Socket network Wake-up (WOL) interface (PCI2.1 standard Nic). Wake On LAN (Network Wake-up) provides the function of Remote Wake-up computers,
It is an achievement of the Advanced management Alliance established in October 1996 by IBM and Intel.
As a result, administrators can remotely wake up computers during non-work hours and automatically complete some management services, such as software updates or virus scanning. It is also
Part of the Wired for Management basic specification. The principle of network wake-up is that a management software Packet-based wake-up is first triggered by a management software Packet.
Frame. The network wake-up Nic analyzes the wake-up frame after receiving it and determines whether the frame contains the MAC address of the NIC. If the MAC address of the network card is included, the computer system automatically enters the boot status.
Status.
Currently, mainstream independent NICs or motherboard onboard NICs comply with PCI2.2 and later specifications. Therefore, you do not need this interface and need to enable the network wake-up function, you only need to enable the "Wake on PCI Card" function in the BIOS of the motherboard.
● Data Mercury

Figure 10 Data Mercury
　
Data mercury is a device on the consumption-level PCI Nic. Data mercury is also called a Network Transformer or a network isolation transformer. It plays two main roles on one network card. One is to transmit data and
The differential signals sent by PHY are filtered by the difference-mode coupling coil to enhance the signal, and are coupled to the other end of the connected network cable at different levels through the electromagnetic field conversion; first, isolate different network devices connected by network cables
Different levels to prevent the device from being damaged by transmission of different voltages over the network cable. In addition, data mercury can also protect the equipment against lightning.
● Crystal Oscillator

Figure 11
　
Crystal oscillator is short for Z oscillator, and its English name is Crystal. It is the most important component in the clock circuit, and its function is to provide the reference frequency to each part of the video card, Nic, motherboard and other accessories, it is like a tag.
If the operating frequency is unstable, the operation frequency of the related equipment is unstable. As the manufacturing process continues to improve, the frequency deviation, temperature stability, aging rate, sealing and other important technologies of the crystal oscillator are now
Indicators are good and it is no longer prone to faults, but you can still pay attention to the quality of the Crystal Oscillator when selecting.
For example, the clock circuit of a network card uses a high-precision sko25 MHz crystal oscillator, which ensures reliability.
This proves the precise synchronization of data transmission, greatly reducing the possibility of packet loss. In addition, the design of the line is as close as possible to the main chip, which greatly shortens the signal line length and further increases the reliability. If inferior crystals are used
Vibration, although this can reduce the cost of a nic, but because of the accuracy of the frequency, it is easy to cause data packet loss during transmission.
● Network cable Interface
Consumption on the desktop
Level network interfaces in the common Nic interfaces BNC interface and RJ-45 interface (similar to the phone interface), there are two interfaces are dual-port Nic. The interface selection is related to the network cabling mode.
In, BNC port Nic connected directly to other computers and servers through coaxial cable; RJ-45 port Nic connected to the HUB (HUB) or switch through twisted pair wire, and then connected to other meter through the HUB or switch
Computing machines and servers.
Currently, interfaces such as BNC interfaces are rarely seen. This is mainly because the number of networks using a fine coaxial cable as the transmission medium is relatively small and there are many problems related to the networking mode.
RJ-45 is 8-core line, while the telephone line interface is 4-core, usually only 2-core line (ISDN telephone line connected to 4-core line); but you can take a closer look, in fact, 10 m Nic RJ-45 plug-in is only used
The first, two, three, six four needles, and m or M Nic is the eight needles are full, this is also a way to distinguish between 10 M and M NICs (see figure 8 ).
● Transmission media type
Speaking of NICs, let's talk about the twisted pair wires connected to NICs.

Figure 12
Twisted Pair wires are a data transmission line consisting of many pairs of cables in an Insulating Coat. They are characterized by low prices. Currently, most network adapters use twisted pair wires as transmission cables. Twisted pair wire is generally used for star network cabling, the two ends of the installation of a RJ-45 (crystal head), the connection network card and the hub, the maximum length of the network cable is about 100.
　
Twisted Pair wires are STP (shielded twisted pair wires) and UTP (unshielded twisted pair wires. STP twisted pair wires have a metal isolation film, which can reduce electromagnetic interference during data transmission, so it has high stability. While
UTP does not have this layer of metal film, so it has poor stability, but its advantage is its low price. Among them, STP (shielded twisted pair wires) is mainly divided into 3 categories and 5 categories, UTP (unshielded twisted pair wires) is mainly
There are three categories, four categories, five categories, over five categories, and six categories. Generally, the network mainly uses Category 5 twisted pair wires and Category 5 twisted pair wires with thick outer protection rubber, mark "CAT5" on the rubber cover. Category 5 twisted pair wires are non-Screen
Compared with common category 5 twisted pair wires, over 5 twisted pair wires have lower attenuation and stronger anti-interference capabilities during signal transmission. In a m network, the interference level of a user's device is only 1/4 of that of a common category 5 cable,
It is also the mainstream application.
● Bus Interface
The NIC must be connected to the computer before it can be used normally, and various interfaces on the computer emerge one after another, which also leads to the type of bus interface used by the NIC.
Brilliant. In addition, when it comes to bus interfaces, it should be noted that people generally call these interfaces "golden finger". Why is it called a golden finger? This is because the pin of this plug-in card uses titanium plating (or other metals ),
It proves the reliable contact during repeated plugging, which increases the anti-interference capability and reduces interference on other devices.
For your convenience, we will illustrate the network interfaces of common interface types.
① ISA interface Nic

Figure 13
　
ISA is a bus interface used by early NICs. The ISA Nic communicates with the CPU by program request I/O. In this mode, the network transmission rate is low, and CPU resources are greatly occupied, mostly 10 M
Nic, at present in the market basically do not see ISA Bus Type Nic, I found several ISA Nic from the old parts heap, D-LINK products, actually use a eraser to clean the Gold finger after the machine can
.
② PCI interface Nic

Figure 14
　
The PCI (peripheral component interconnect) bus slot is still the most basic interface on the motherboard. It is based on a 32-Bit Data Bus and can be expanded
It operates at 33 MHz/66 MHz. The data transmission rate is 132 MB per second (32*33 MHz/8 ). At present, the PCI interface Nic is still the absolute master in the household consumption market
Stream.
③ PCI-X interface Nic

Figure 15
　
PCI-X is an extended architecture of the PCI bus. Unlike the PCI bus, the PCI bus must frequently exchange data between the target device and the bus, while the PCI-X allows the target device to only
A single PCI-X device looks exchange, and if the PCI-X device does not have any data transfer, the bus automatically removes the PCI-X device to reduce the wait cycle between PCI devices. Therefore
At the same frequency, the PCI-X will provide 14-35% higher performance than PCI. Currently, the server Nic often uses this type of interface Nic.
PCI-E Interface Card

Figure 16
　
The PCI Express 1X interface has become a required interface for mainstream mainboards. Different from parallel transmission, the PCI Express interface uses point-to-point serial connection
The PCI Express interface varies according to the bus interface's requirements for Bit Width. It is divided into PCI Express 1X (Standard 250 MB/s, bidirectional 500 MB
/S), 2X (Standard 500 MB/s), 4X (1 GB/s), 8X (2 GB/s), 16X (4 GB/s), 32X (8 GB/s ). Nic with PCI-E Interface
Most are Gigabit NICs.
⑤ USB interface Nic

Figure 17
　
It is difficult to find the USB interface (Universal Serial Bus) on the current computer. The USB Bus is divided into USB and USB
Accurate. The theoretical value of the USB 480 standard transmission rate is 12 Mbps, while the USB standard transmission rate can be up to Mbps. Currently, most USB cable NICs are USB standard
Accurate.
⑥ PCMCIA Interface Nic

Figure 18
The PCMCIA Interface is a dedicated interface for laptops. The PCMCIA bus is divided into two types: one is a 16-bit PCMCIA Interface and the other is a 32-bit cartana interface. The maximum throughput of the carw.nic is close to 90 Mbps, it is currently the mainstream commercial laptop network card.
7. Mini-PCI interface Nic

Figure 19
The MiniPCI interface is an interface standard extended based on the desktop PCI interface for laptops. Its speed is equivalent to the PCI standard, and many such products are wireless NICs.
In addition, there are network cards for interfaces such as AMR on the market, which will not be described in this article due to the limited length and popularity.