first, the basic concept of LAN networking
A local area network (LAN) is a computer network that is distributed within a relatively small distance range.
(1) LAN standard: IEEE802 standard
The IEEE802 standard includes the local area network reference model and each layer protocol, which describes the relationship between the local area network reference Model and the OSI reference Model.
The comparison chart looks like this:
(2) Basic concept of switched LAN
The switched LAN is relative to the shared LAN. It is characterized by low switching latency, support for different transfer rates and operating modes, and the ability to support virtual LAN services.
traditional shared media LAN, all nodes share a transmission medium, because of the inevitable conflict of wealth.
The core of the switched LAN is the LAN switch. A LAN switch can establish multiple concurrent connections between its multiple ports. It mainly adopts two kinds of conversion modes: Fast switching mode and storage and forwarding Exchange Mode.
A typical switched LAN is switched Ethernet, and its core component is the Ethernet switch. An Ethernet switch can have multiple ports, each of which can be connected separately to one node or to a shared media Ethernet hub.
(3) Basic concept of virtual local area network
1) Virtual local area network (Lan,vlan) is based on the exchange technology, it is a software approach to the network nodes according to the nature of the work and the need to divide into a number of "logical Workgroup", each logical workgroup is a virtual network.
IEEE1999 released the ieee802.1q standard for VLANs. Nodes of a logical workgroup can be distributed across different physical network segments, but they communicate as if they were on the same physical network segment. They can be organized according to such factors as function or application, and communicate with each other as if they were in the same network segment.
2) There are typically four ways to define a virtual LAN network:
A) port-based virtual local area network
b) Virtual local area network based on MAC address definition
c) Virtual LAN based on network layer address definition
d) Virtual local area network based on IP broadcast Group
The physical structure and logical structure of a typical virtual network are:
Second, the concept of integrated cabling
(1) Integrated cabling is a modular, highly flexible information transmission channel between buildings or buildings. It can be both voice, data, image devices and switching devices that are connected to other information management systems and can be connected to external devices. It also includes all the cables and associated connection parts between the connection point of the building's external network or telecommunication line and the application equipment.
(2) The integrated wiring consists of different series and specifications of the components, including: transmission media, related connected hardware (such as wiring racks, connectors, sockets, plugs, adapters), as well as electrical protection equipment. These components can be used to build subsystems that have their own specific purpose, are easy to implement, and can be upgraded smoothly as demand changes.
(3) Characteristics of the integrated cabling
The characteristics of the integrated cabling are mainly manifested in its compatibility, openness, flexibility, reliability, advanced nature and economic performance. And in the design, construction and maintenance of people also bring a lot of convenience.
(4) The composition of the Integrated Cabling system:
A) Work area subsystem.
b) wiring (horizontal) subsystem
c) Trunk (vertical) subsystem
d) Inter-device subsystem
e) Management Subsystem
f) Complex subsystems
subsystem composition diagram of the Integrated cabling system:
(5) Integrated cabling system design level
Depending on the actual needs, the following three types of integrated cabling systems can be selected:
A) Basic type
The basic integrated cabling system is a cost-effective cabling scheme. It features 1 information sockets per work area, 1 horizontal cabling in each workspace 4 pairs of unshielded twisted pair. Clamp-on handover hardware is fully used. There are at least 1 pairs of twisted pairs in the trunk cable for each work area.
It is suitable for the low configuration standard in the integrated cabling system, with the copper core twisted wire cable network.
b) Enhanced Type
Enhanced integrated cabling System not only supports voice and data applications, but also supports images, videos, movies, video conferencing
And so on, it is characterized by: each work area has more than 2 information sockets. The wiring cable for each work area is 2 4 pair unshielded twisted pair. Use clamp-on or plug-in transfer hardware. There are at least 2 pairs of twisted pairs in the trunk cable for each work area.
It is suitable for the medium configuration standard in the general wiring system, with the copper core twisted wire cable network.
c) Integrated type
The integrated cabling system is a system that incorporates twisted-pair and optical cables into the building's cabling, characterized by:
An optical fiber cable system is added on the basis of basic and enhanced integrated cabling system. There are at least 2 pairs of twisted pairs in the trunk of each basic work area. There are at least 3 pairs of twisted pairs in the trunk cable for each enhanced work area.
It is suitable for the high configuration standard in the integrated cabling system, and the hybrid network of the copper core twisted-pair cable with optical cable.
(6) Integrated Cabling System standard
Now, the general wiring in the reference system cabling standards, generally from the following standard system start: the Americas standards, European standards, international standards and application standards.
A) North American standard Ansi/tia/eia568-b.
b) ansi/tia/eia568-b.1,ansi/tia/eia568-b.2,ansi/tia/eia568-b.3.
c) International standard ISO/IEC 11801
d) China standard gb/t50311-2000 and gb/t50312-2000
Three, the basic method of Ethernet networking
(1) The method of naming the physical layer standard of Ethernet
It is named by the various physical layer standards of Ethernet, and its name consists of three parts.
Traditional Ethernet physical Layer standard naming method:
where x is the rate at which the Ethernet data is transmitted, the unit is mb/s;type for transmission, baseband or band; Y is the maximum length of the network, and the unit is 100m,;name is the name of the LAN.
(2) Design method of 10BASE-T standard Ethernet Networking
Standard (Traditional) Ethernet can choose one or several combinations of 10base-5,10base-2 or 10base-t. The current standard design is based on the 10BASE-T standard, using hubs, unshielded twisted-pair and RJ-45 interfaces.
10BASE-T Network consists of network card, hub, switch, twisted pair and other equipment. Nodes are connected to a hub via a twisted pair, and when one of the nodes sends the data, any node can receive a message, the hub works in the physical layer, and all nodes connected to a hub belong to the same conflict domain. In any one time period, only one node can send the data frame, while the other nodes can only be in the receive State.
Ethernet diagram for connecting multiple nodes with a hub:
(3) According to the way of using the hub, the twisted pair network method can be:
A) 10base-t network with single hub
b) for ethrenet of stacked hubs
c) Multi-hub Cascade Ethernet
(4) Design method of Fast Ethernet networking
1) basic features of Fast Ethernet:
A) The Fast Ethernet protocol standard is 802.3u protocol.
b) Keep the traditional Ethernet frame structure and media access control method unchanged.
c) Use the IEEE802.3 Standard in the LLC Sublayer and use the CSMA/CD method in the Mav sublayer.
d) data transfer rate increased to 100Mbps.
E) provides 10Mbps and 100Mbps rate auto-negotiation function.
IEEE802.3U Architecture Diagram:
2) Fast Ethernet media Dedicated interface Mii
To mask the different physical details of the lower layers, 100BASE-T provides a common transparent interface for Mac and high-level protocols with a 100M transfer rate, with the same functionality as the Ethernet AUI interface. The Mii interface provides a signal for carrier interception and collision detection up to the pretext of the Mac sub-layer, which supports 10mb/s and 100mb/s, while the hub can exchange control information with it.
Fast Ethernet Media Dedicated interface Mii main features:
A) Mii separates the Mac sub-layer from the physical layer
b) Mii up-up through the interface with the MAC sub-layer to provide carrier interception signal and collision detection (CSMA/CD) signal, down support 10Mbps and 100Mbps speed of the interface, as well as with the hub to exchange control information functions.
3) physical layer standard for Fast Ethernet
A) 100base-tx: using the 5 class unshielded twisted pair or shielded twisted pair Fast Ethernet technology, it uses two pairs of twisted pair, a pair for sending, a pair for receiving data, using 4B/5B encoding method in the transmission. It has an Ethernet segment length of 100m. It supports full-duplex data transfer.
b) 100base-fx: The use of 2 fiber, the maximum length of 415m, one fiber for transmission, the other for acceptance, data transmission using 4b/5b-nrzi encoding method, the use of full duplex operation.
c) 100BASE-T4: It uses 4 pairs of 3 unshielded twisted pairs, 3 pairs for transmitting data, and 1 pairs for detecting conflicting signals. Using the 8B/6T encoding method in the transmission, it uses the same RJ-45 connector as 100BASE-T, with a maximum segment length of 100m and half-duplex operation.
Comparison table of three physical layer standards:
4) Full-duplex and half-duplex operation mode
Full duplex refers to the presence of a-to-B and B-to-a bidirectional signal transmission on the line at any point in the communication. In full duplex mode, each segment of the communication system is set up with transmitters and receivers. As a result, the data can be controlled in two directions simultaneously.
Half-duplex refers to the communication process at any time, the information can be from a to B, but also from B to a, but only one direction of transmission exists.
is different from the traditional Ethernet connection mode. The full-duplex operation is the mid-point connection mode, and the topology of the Fast Ethernet that supports full-duplex mode must be star-shaped.
Traditional Ethernet has many hosts connected to a shared coaxial cable, the host need to fight for shared transmission media, so there is a CSMA/CD media access control method. Point-to-point connection method There is a problem. Therefore, the media access control method is not required.
5) Auto-negotiation function of 100mb/s and 10mb/s rate
A) automatic determination of unshielded twisted pair New Year's Day the connecting device uses a half-duplex (CSMA/CD) 10Mbps operating mode, or a full-duplex 100Mbps operating mode.
b) Publish the operating mode of the remote connection device to other nodes.
c) Exchange working mode parameters with the remote connection device, negotiate and determine the working mode of the two sides.
d) Auto-negotiation function automatically selects common high-performance working mode.
The autonegotiation process can only be used with twisted-pair Ethernet, and the fixed auto-negotiation process needs to be done within 100ms.
According to the performance from high to low, the network protocol priority ranking from high to first ranked as:
100base-tx or 100BASE-FX full duplex mode
100base-t4 Half Duplex mode
100base-tx Half Duplex mode
10base-t Full Duplex mode
10base-t Half Duplex mode
Four, LAN interconnection device type
(1) Repeater
A repeater is a connection device above the physical layer of a network. It is suitable for the identical two kinds of network interconnection, the main function is to enlarge the distance of network transmission by re-transmitting or forwarding the data signal.
Repeater Connection diagram:
A repeater is a device that connects network lines and is often used for two-way forwarding of physical signals between two network nodes. Repeater is the simplest network interconnection equipment, mainly to complete the physical layer function, responsible for the two nodes in the physical layer of the bit to transmit information, complete information replication, adjustment and amplification function, in order to extend the length of the network.
The repeater works in the physical layer, and its work is to send the attenuated signal after receiving, amplifying, shaping and then connecting to another cable segment. The purpose of the repeater is to increase the length of the transmission medium, and the nodes it connects to still share a conflict domain, so the repeater is not part of the network Interconnect device.
How the Repeater works:
543 rule: Is the Ethernet standard specifies that the Ethernet only allow 5 network segments, up to 4 repeaters, and only 3 of them can be connected to the computer terminal. That's why we call it the 543 rule.
(2) Hub
A hub is a multiport relay that differs only in that the repeater only connects two network segments, and the hub can provide more port services. The CSMA/CD media access control method is still used. All nodes connected to a hub share a conflict domain.
You can listen for packets in the link by stringing a hub in the network link. Multiple nodes connected to a hub cannot send data frames at the same time, and can accept data frames simultaneously.
Hub in English is called "hub", that is, the meaning of "center", the main function of the hub is to connect the received signal to re-shape and enlarge, in order to enlarge the transmission distance of the network, at the same time, all the nodes concentrated in its central node, the establishment of a physical star network structure. Its working physical layer adopts CSMA/CD media access control mode.
The hub works with the following two features:
A) The hub is just a multi-port signal amplification device that only acts as a signal amplification and transmission in the network.
b) The hub communicates only with its up-and-down devices, and the ports on the same layer do not communicate directly, but through the upper devices on all the ports of the spoke information broadcast channel.
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LAN Technology (i)
