The literacy of Ethernet knowledge is mainly to introduce the interface.
1. Introduction to Ethernet
Ethernet is a computer local area network technology. The IEEE 802.3 standard of the IEEE organization has established the technical standard of Ethernet, which stipulates the content of the connection, electronic signal and medium access layer protocol including the physical layer. Ethernet is the most widely used LAN technology, replacing other LAN technologies such as Token Ring, FDDI, and ARCNET.
Classic Ethernet:
A long cable snakes around the building, and this cable connects all the computers.
Switched Ethernet :
Different computers are connected using a device called a switch
Two, network card
Network Interface Card (NIC for short), also known as a network adapter, is a device that connects a computer to a local area network.
A network card mainly includes the bottom two layers of OSI, the physical layer and the data link layer
1. The physical layer defines the electrical and optical signals, line status, clock reference, data encoding and circuits required for data transmission and reception, and provides standard interfaces to data link layer devices. The physical layer chip is called PHY
2. The data link layer provides functions such as addressing mechanism, data frame construction, data error checking, transmission control, and standard data interface to the network layer. The data link layer chip is called the MAC controller
PHY integrates a large number of analog hardware, and MAC is a typical all-digital device. The chip area and analog/digital hybrid architecture are the reasons why MAC is first integrated into the microcontroller and PHY is left off-chip. More flexible and denser chip technology has enabled single-chip integration of MAC and PHY
3. Ethernet interface
SC fiber optic interface
The SC optical fiber interface is mainly used in the LAN switching environment. This interface is provided on some high-performance Ethernet switches and routers. It looks similar to the RJ-45 interface, but the SC interface is flatter. The obvious difference is the inside If it is 8 thin copper contacts, it is the RJ-45 interface, if it is a copper column, it is the SC optical fiber interface
RJ-45 interface
This kind of interface is our most common network equipment interface, commonly known as "crystal head", the technical term is RJ-45 connector, which belongs to the twisted pair Ethernet interface type. The RJ-45 plug can only be inserted in a fixed direction, and there is a plastic shrapnel stuck with the RJ-45 slot to prevent it from falling off. This interface can be used in 10Base-T Ethernet, 100Base-TX Ethernet, and 1000Base-TX Ethernet. When connecting to TX Gigabit Ethernet, at least Category 5e cables must be used, and Category 6 cables must be used to ensure stable high speed.
FDDI interface
Fiber Distributed Data Interface (FDDI) is a set of protocols developed by the American National Standards Institute (ANSI) for sending digital signals over optical cables. FDDI interface is more common on network backbone switches. With the popularity of Gigabit, some high-end Gigabit switches have also begun to use this interface.
AUI interface
The AUI interface is specially used to connect thick coaxial cables. Early network cards have such interfaces connected to hubs and switches to form a network, which is generally not used. The AUI interface is a "D" type 15-pin interface, which was previously used in the token ring network or bus network. It can be connected with the 10Base-T Ethernet network with the help of an external transceiver (AUI-to-RJ-45). Connection
BNC interface
BNC is an interface specially used to connect with thin coaxial cables. Thin coaxial cables are what we often call "thin cables". Its most common application is a separate display signal interface, which uses red, green, blue and horizontal , The vertical scanning frequency is separated from the interface of the input display, and the interference between signals is smaller. BNC is basically no longer used in switches, only some early RJ-45 Ethernet switches and hubs still provide a few BNC interfaces
Console interface
Ethernet switches capable of network management generally have a "Console" port, which is specially used to configure and manage the switches. Connecting and configuring the switch through the Console port is a necessary step for configuring and managing the switch
Four, MII, RMII, GMII, RGMII connector
MII: 100M Ethernet interface, single-edge sampling.
RMII: 100M Ethernet interface, a simplified version of MII, double-edge sampling.
GMII: Gigabit Ethernet interface, single-edge sampling.
RGMII: Gigabit Ethernet interface, simplified version of GMII line, double edge sampling.
MII
(Media Independent interface) is a media-independent interface, which is an industry standard defined by IEEE-802.3, and is an interface between MAC and PHY. MII data interface contains 16 signals and 2 management interface signals
RMII
RMII (Reduced Media Independant Interface), simplifies the MII interface, saving half of the data lines. RMII transmit and receive uses 2-bit data for transmission, and both transmit and receive clocks use a 50MHz clock source
WWII
GMII (Gigabit Media Independant Interface), gigabit MII interface. GMII uses 8-bit interface data, and the working clock is 125MHz, so the transmission rate can reach 1000Mbps. At the same time, it is compatible with the 10/100 Mbps working method stipulated by MII. The data structure of the GMII interface conforms to the IEEE Ethernet standard, and the interface definition is defined in IEEE 802.3-2000. The signal is defined as follows:
RGMII
RGMII (Reduced Gigabit Media Independant Interface), streamlined GMII interface. Compared with GMII, RGMII has the following characteristics:
Send/receive data lines changed from 8 to 4
TX_ER and TX_EN are multiplexed and transmitted through TX_CTL
RX_ER and RX_DV are multiplexed and transmitted through RX_CTL
At 1 Gbit/s rate, the clock frequency is 125MHz
At 100 Mbit/s, the clock frequency is 25MHz
At 10 Mbit/s rate, the clock frequency is 2.5MHz
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