- Jan 19, 2019-


Ethernet refers to the baseband LAN specification created by Xerox and jointly developed by Xerox, Intel and DEC. The universal Ethernet standard was released on September 30, 1980, which is the most common in today's existing LANs. Communication protocol standard. The Ethernet network uses CSMA/CD (Carrier Sense Multiple Access and Collision Detection) technology and runs on multiple types of cables at 10M/S. Ethernet is similar to the IEEE802.3 family of standards. Includes standard Ethernet (10Mbit/s), Fast Ethernet (100Mbit/s) and 10G (10Gbit/s) Ethernet. They are all compliant with IEEE 802.3.



Starting Ethernet with only 10 Mbps throughput, the access control method with carrier sense multiple access (CSMA/CD, Carrier Sense Multiple Access/Collision Detection) with collision detection is used. This early 10 Mbps Ethernet is called standard Ethernet, and Ethernet can be connected using a variety of transmission media such as thick coaxial cable, thin coaxial cable, unshielded twisted pair, shielded twisted pair, and fiber. And in the IEEE 802.3 standard, different physical layer standards are defined for different transmission media. In these standards, the first digit indicates the transmission speed in units of "Mbps", and the last digit indicates the length of the single segment cable (the reference unit is 100m), Base means "baseband" and Broad means "broadband."

10Base-5 uses a 0.4-inch diameter, 50Ω thick coaxial cable, also known as thick Ethernet, with a maximum segment length of 500m. Baseband transmission method, the topology is bus type. The main hardware devices of the 10Base-5 network include: thick coaxial cable, Ethernet card with AUI socket, repeater, transceiver, transceiver cable, and terminator.

10Base-2 uses a 0.2-inch diameter, 50Ω thin coaxial cable, also known as thin cable Ethernet, the maximum network segment length is 185m, baseband transmission method, topology is bus type; 10Base-2 network main hardware equipment Available: thin coaxial cable, Ethernet card with BNC socket, repeater, T-connector, terminator, etc.

10Base-T uses a twisted pair cable with a maximum segment length of 100m. The topology is star-shaped; the main hardware devices of the 10Base-T network are: Category 3 or Category 5 unshielded twisted pair cable, Ethernet card with RJ-45 socket, hub, switch, RJ-45 plug, etc.

1Base-5 uses twisted pair cable, the maximum segment length is 500m, and the transmission speed is 1Mbps.

10Broad-36 uses coaxial cable (RG-59/U CATV), the maximum span of the network is 3600m, and the network segment length is up to 1800m, which is a broadband transmission mode;

10Base-F uses fiber optic transmission media at a transmission rate of 10Mbps.

Fast ether

Ethernet With the development of the network, traditional standard Ethernet technology has been difficult to meet the increasing demand for network data traffic. Prior to October 1993, only the Fiber Distributed Data Interface (FDDI) was available for LAN applications requiring data traffic above 10 Mbps, but it was a very expensive LAN based on 100 Mbps fiber optic cable. In October 1993, Grand Junction introduced the world's first Fast Ethernet hub Fastch 1080 and the network interface card FastNIC 100. The Fast Ethernet technology was officially applied. Then Intel, SynOptics, 3COM, BayNetworks and other companies have also launched their own Fast Ethernet devices. At the same time, the IEEE 802 engineering group also studied various standards of 100Mbps Ethernet, such as 100BASE-TX, 100BASE-T4, MII, repeater, full duplex and other standards. In March 1995, the IEEE announced the IEEE802.3u 100BASE-T Fast Ethernet standard, which began the era of Fast Ethernet.

Fast Ethernet has many advantages compared with FDDI, which was originally operated at 100Mbps bandwidth. The main reason is that Fast Ethernet technology can effectively protect users' investment in wiring infrastructure implementation. It supports 3, 4, and 5 pairs of dual The connection of the stranded wire and the optical fiber enables efficient use of existing facilities. The lack of Fast Ethernet is also a drawback of Ethernet technology. That is, Fast Ethernet is still based on CSMA/CD technology. When the network load is heavy, it will cause efficiency reduction. Of course, this can be compensated by switching technology. The 100Mbps Fast Ethernet standard is further divided into three subclasses: 100BASE-TX, 100BASE-FX, and 100BASE-T4.

· 100BASE-TX: A Fast Ethernet technology that uses Category 5 data-level unshielded twisted pair or shielded twisted pair. It uses two pairs of twisted pairs, one for sending and one for receiving data. The 4B/5B encoding method is used in the transmission, and the signal frequency is 125 MHz. Meets EIA586's Category 5 cabling standard and IBM's SPT Class 1 cabling standard. Use the same RJ-45 connector as 10BASE-T. Its maximum network segment length is 100 meters. It supports full-duplex data transfer.

· 100BASE-FX: A fast Ethernet technology that uses fiber optic cable to use both single-mode and multimode fiber (62.5 and 125um). The maximum distance for multimode fiber connections is 550 meters. The maximum distance for single mode fiber connections is 3000 meters. The 4B/5B encoding method is used in the transmission, and the signal frequency is 125 MHz. It uses a MIC/FDDI connector, an ST connector or an SC connector. Its maximum network segment length is 150m, 412m, 2000m or longer to 10km, which is related to the type of fiber used and the mode of operation. It supports full-duplex data transmission. 100BASE-FX is especially suitable for applications with electrical interference, large distance connections, or high security environments.

· 100BASE-T4: is a Fast Ethernet technology that can be used with Category 3, 4, and 5 unshielded twisted pair or shielded twisted pair. The 100Base-T4 uses four pairs of twisted pairs, three of which are used to transmit data at a frequency of 33 MHz, each pair operating in half-duplex mode. The fourth pair is used for CSMA/CD collision detection. The 8B/6T encoding method is used in the transmission, and the signal frequency is 25MHz, which conforms to the EIA586 structured wiring standard. It uses the same RJ-45 connector as 10BASE-T with a maximum segment length of 100 meters.

Gigabit ether

As the latest high-speed Ethernet technology, Gigabit Ethernet technology provides users with an effective solution to improve the core network. The biggest advantage of this solution is the inheritance of the advantages of traditional Ethernet technology. Gigabit technology is still Ethernet technology, it uses the same frame format, frame structure, network protocol, full/half duplex mode, flow control mode and wiring system as 10M Ethernet. Because this technology does not change the desktop applications and operating systems of traditional Ethernet, it works well with 10M or 100M Ethernet. Upgrading to Gigabit Ethernet does not require changes to network applications, network management components, and network operating systems to maximize investment protection. In addition, the IEEE standard will support multimode fiber with a maximum distance of 550 meters, single mode fiber with a maximum distance of 70 kilometers, and coaxial cable with a maximum distance of 100 meters. Gigabit Ethernet fills the gap in the 802.3 Ethernet/Fast Ethernet standard.

In order to be able to detect collisions of 64 Bytes data frames, Gigabit Ethernet supports shorter distances. The network types supported by Gigabit Ethernet are as follows:

Transmission medium distance

1000Base-CX Copper STP 25m

1000Base-T Copper Cat 5 UTP 100m

1000Base-SX Multi-mode Fiber 500m

1000Base-LX Single-mode Fiber 3000m

Gigabit Ethernet technology has two standards: IEEE 802.3z and IEEE 802.3ab. IEEE 802.3z sets the standard for fiber and short-range copper wire connections. IEEE 802.3ab sets the standard for a five-way twisted pair long-haul connection scheme.

1. IEEE 802.3z

The IEEE 802.3z working group is responsible for the development of full-duplex link standards for fiber (single mode or multimode) and coaxial cable. IEEE 802.3z defines 1000Base-X based on fiber optic and short-distance copper cables. It uses 8B/10B encoding technology, and the channel transmission speed is 1.25Gbit/s. After decoupling, it achieves 1000Mbit/s transmission speed. IEEE 802.3z has the following Gigabit Ethernet standards:

· 1000Base-SX only supports multimode fiber. It can use multimode fiber with diameter of 62.5um or 50um. It has a working wavelength of 770-860nm and a transmission distance of 220-550m.

· 1000Base-LX single-mode fiber: It can support single-mode fiber with a diameter of 9um or 10um. The operating wavelength range is 1270-1355nm and the transmission distance is about 5km.

· 1000Base-CX uses 150 ohm shielded twisted pair (STP) with a transmission distance of 25m.

2. IEEE802.3ab

The IEEE 802.3ab Working Group is responsible for the development of the Gigabit Ethernet standard for UTP-based half-duplex links, resulting in the IEEE 802.3ab standard and protocol. IEEE 802.3ab defines the 1000Base-T standard based on Category 5 UTP, which aims to transmit 100m at a rate of 1000 Mbit/s over Category 5 UTP. The IEEE802.3ab standard has two main points:

(1) Protect users' investment in Category 5 UTP cabling systems.

(2) 1000Base-T is a 100Base-T natural extension, fully compatible with 10Base-T and 100Base-T. However, achieving a transmission rate of 1000 Mbit/s on Category 5 UTP requires solving the crosstalk and attenuation problems of Category 5 UTP. Therefore, the development task of the IEEE802.3ab working group is more complicated than IEEE802.3z.

10 Gigabit Ethernet

The 10 Gigabit Ethernet specification is included in the IEEE 802.3ae supplemental standard IEEE 802.3ae, which extends the IEEE 802.3 protocol and MAC specification to support 10Gb/s transmission rates. In addition, through the WAN interface sublayer (WIS: WAN interfacesublayer), 10 Gigabit Ethernet can also be adjusted to a lower transmission rate, such as 9.584440 Gb/s (OC-192), which allows 10 thousand Megabit Ethernet devices are compatible with the Synchronous Optical Network (SONET) STS-192c transport format.

· 10GBASE-SR and 10GBASE-SW mainly support short-wave (850 nm) multimode fiber (MMF) with fiber distances from 2m to 300m.

10GBASE-SR mainly supports "dark fiber", which is a fiber that does not have light propagation and is not connected to any device.

10GBASE-SW is primarily used to connect SONET devices for remote data communication.

· 10GBASE-LR and 10GBASE-LW mainly support long-wave (1310nm) single-mode fiber (SMF) with a fiber distance of 2m to 10km (about 32,808 feet).

When 10GBASE-LW is mainly used to connect SONET devices,

10GBASE-LR is used to support "dark fiber".

· 10GBASE-ER and 10GBASE-EW mainly support ultra long wave (1550nm) single mode fiber (SMF) with a fiber distance of 2m to 40km (about 131233 feet).

10GBASE-EW is mainly used to connect SONET devices.

10GBASE-ER is used to support "dark fiber".

· 10GBASE-LX4 uses wavelength division multiplexing technology to transmit signals at four times the wavelength of light on a single pair of cables. The system operates in a 1310nm multimode or singlemode dark fiber mode. The system is designed for multimode fiber mode from 2m to 300m or single mode fiber mode from 2m to 10km.