CCNA基础必学篇,入门教程,热点VIP

1、knowledge of the web is boring, and there is no strong foundation for it.good finishthe three basic elements of the network:what role does the agreement play in network cormectivity?what are the main transmission media? what are the functions?network services (what is the concept of web services?)th

2、e function of the computer network:1, the shared resourcenetwork communication between usersdistributed processing (what is distributed processing)centralized management (how to manage centrally?)load balancing (the role of load balancing)the concept of network protocol:network protocol is to contro

3、l the computer network and orderly, correct the terms of the commonly known as data transmission and network protocol is embodied in the operating system andsome applications in the process of writing, know the network protocol for network transmission control mechanism of the process, will help to

4、understand the causes of network fault, more rapid troubleshootingcomputer network classification:according topological type: total linear network, star network, loop network, networkthe way it provides services: peer-to-peer networks, server/client networksdivide by distributed distance: lan, city

5、wan, wanunderstand the internet from a macro perspectiveon the macro level, the network can be divided into three levels: the access layer, the aggregation layer, the core layerwe have a micro understanding of the webthe osi seven layer model:physical layer, data link layer, network layer, transport

6、 layer, session layer, presentation layer, application layerapplication layer: where the application is locatedpresentation layer: data compression and decompression, encryption and decryption, encoding and decodingsession layer: the location of the operating systemtransport layer: provides the loca

7、tion where the end is locatedtransport layer: provides end-to-end connectivitynetwork layer: ip address, where the routing protocol is locateddata link layer: the location of the mac addressphysical layer: bitstream, bandwidththe process of adding "headers" to the original data is called e

8、ncapsulation, and the process of reducing the bit str earn to the original data is called unpackingpdu: the protocol data unit, each layer of pdu has its own name, 4 is called segment, 3 layer is called package, 2 second is framenetwork devices:common network equipment: repeaters, hubs, bridges, rou

9、ters, firewalls, wireless devicestransmission medium:copper medium, light ring, wirelessthe router firstthe main internal components of a router and its featuresrandom memory (ram) : store routing tablesaddress resolution (arp) cachefast switchingpacket buffer (shared ram)group hold (packer - hold)

10、queueafter the router is energized, the router is responsible for providing the temporary kernet s memory for the router configuration f订eafter the router is restarted or closed, the contents of the ram are lostnon-volatile random access memory (nvram) : the content remains after the backup/launch p

11、rofile of the storage router restarts or closes the routerflash memory (flash) : erase, programmable read-only memory (eprom) has operating system image and microcodea chip that allows the software to be upgraded without changing the processorafter the router is restarted or closed, the content rema

12、insstore multiple versions of cisco ios software in flash memoryread-only memory (rom) : store the instructions required for a self-test (post) diagnosisholds the bootstrap and operating system softwaresoftware updates in rom need to replace pluggable chips in the cpuinterface: for network connectio

13、n, grouping through interface entry and leaving router can be on the motherboard, or in a separate interface modulerouter functionphysical interconnection, logic interconnection, router computing and maintenance, securitythe interface typethe router interfacelan interface: aui interface: rj-45 port:

14、 sc portwan interface: high-speed synchronous serial port:router operating system:ios (internet option system) internet processing systemios features: 1, which provides a user interface to cisco devicesa dedicated operating system that cannot be grafted and cannot be developed and installed based on

15、 ittext manipulation mode, unlike most graphical operation modes nowa single system file, which is a fileit can be found that there are various types of interfaces, and the system contains the drivers of various modulesthe boot process of a routerstep one: self-checkpart 2: load system files, iospar

16、t 3: load configuration informationstep 4: implement network communicationthe router's basic configuration (1)three ways to configure your router:sonsole mouthaux: a secondary inlerface that enables remote dial-up accesstenet of httpthe super terminal login routerper second digits: 9600data bits

17、; 8parity check: 1.data flow control: noa router startupvisible start process, memory size, ios version, interface andhardware deviceethernet basedethernet history:in september 1980, the dix ethernet 1.0 specification, theethernet blue book was published1982 the dix ethernet 2. 0 specificationin 198

18、3, the ieee802. 3 came out in 10base-5in 1983, the 10base-2 cable ethernet became the officialstandardethernet was born: 1973traditional ethernet: 1983fast ethernet: 1995gigabit ethernet: 1998gigabit ethernet: 2003the reason ethernet can continue to growopen standards and receive support from numero

19、us service providerssimple structure, convenient management and low pricecontinuous technical improvement to meet the needs of usersthe network can be smooth and upgraded to protect user investmentethernet naming rulesieee 802.3 x type - y namex is the rate of transmission10 say 10 mbps100 said 100

20、mbps1000 said 1000 mbpstype represents the way the signal is transmittedbase refers to baseband transmissionbroad refers to broadband transmissiony is the transmission mediumthe coaxial cable is 500 meters awayfinger coaxial cable distance of 200 metersf:optical fibert:l;the twisted pairlong waves:s

21、hort wavec:x；coaxial cablefull duplexname represents the name of the lanethernet, etherneti* m going to go to the fastest ethernetgigaehternet, gigabit ethernetfor example, ieee 802.3 lobaset ethernet, usually abbreviated to lobasetsimplex duplex modefull duplex: transfer data to both parties at any

22、 timehalf duplex: a single direction of transmission can be achieved at a certain time, but can be transmitted by both sides in different time periodssimplex: only allows single direction of transmission at any time.ethernet classification:traditional ethernet:shared ethernetswitching ethernetfast e

23、thernetgigabit ethernetwan zhao ethernetmac (media access control) addressthe physical address on the network card so 48 bits, and then we're going to see that we're going to see a 16-digit number that's 12the mac addressin ethernet, if a device hope to send data to another device, it ca

24、n be through the use of its own mac address to open a route to the device when data from a source device to the network, the data also is bearing the weight of the mac address of purpose, once the data spread along the network media, the nic in each device on the network will check whether data fram

25、e contains the physical address of the match with its own mac address, if don，t match the nic discarding the data frame if the match is matched, the nic makes a copy of it and takes the data from the envelope to the computer, which is processed by a high-level protocol such as ip and tcpcisco equipm

26、ent first and network wiring1, cables and proceduresthe process of the double stranded wire is as followsopen the line in line and line in linecarefully pinch the end of the thread and put it into the 8 grooves of the crystal head. press tight3, tighten the line of the crystal head with a special cl

27、ampnetwork topologymesh typeany device in the network has a separate connection to all other devicesset the linear (hub)hub，s characteristics: the hub is simply a data sent to all ports that is received by a port, without filtering or logical processing of the addressswitchesfeatures: switch port and node through the principle of matching, guarantee the validity of the connection between each port, so as to limit the conflict between the two, so as to solve the first layer equipment conflict problemthe router manages the broadcast domain through its own port, thereby enabl