CMTS configuration contents are: downlink frequency modulation down, down power equality. Downlink frequency in the specified frequency range can be set, but in order not to interfere with other channel signals, with reference to the selected cable TV channels specified by the table on the frequency. Consideration should be given the choice of modulation channel transmission quality. In addition, you must set the DHCP, TFTP server's IP address, CMTS's IP address. After the completion of the above, the middle of the line if no fault, the attenuation of the signal level to meet the requirements, then start the DHCP, TFTP server, and Cable Modem in the front-end communication channel between the establishment of normal.
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1 1 describes the status of network speed dial 1.PSTN: The earliest the most widely used means of access 2.ISDN dial-up: Call the Internet things correct 3.DDN line: for group companies 4.ADSL: Personal Broadband popular for 5.VDSL: more high-speed broadband access 6.Cable-modem: 7 for the cable network. passive optical network access: fiber to the home 8.LMDS access: Wireless Communications 9 . FTTX + LAN: mature technology and low cost of the resource potential of cable television network 2 3 Cable Modem 3.1 principles and the use of what is Cable Modem3.3 Cable Modem system configuration, use and management of a network speed of the status of an introduced today, the network development has provided us with more room for development and opportunities. But the network transmission speed is limited more and more obstacles to the development of the network itself. A series of new Internet services, including audio, streaming video, local information services (community information and services), video on demand and numerous other online services, are subject to network speed and not widely used. Even the WWW (World Wide Web, World Wide Web, literally meaning One word, but it reflects the frustration, needs and expectations. As a result, people began to study various competing Internet broadband access technology. Such as ISDN (Integrated Service Digital Network, Integrated Services Digital Network, commonly known as This article is another solution: the use of Cable Modem (cable modem) to access the computer cable network, network operations, including the nowadays popular Internet access: 1.PSTN Dial-up: the most widely used means of access early PSTN (Public Switched Telephone Network, Public Switched Telephone Network) 2.ISDN Dial-up: Call the Internet things correct ISDN (Integrated Service Digital Network, Integrated Services Digital Network) 3.DDN line: for group companies Digital Data Network DDN is the abbreviation of the English 4.ADSL: popular for personal broadband ADSL (Asymmetrical Digital Subscriber Line, Asymmetric Digital Subscriber Loop) 5.VDSL: higher-speed VDSL broadband access faster than ADSL. 6.Cable-modem: for cable TV network Cable-Modem (cable modem) 7. Passive optical network access: FTTH PON (passive optical network) technology is a multipoint optical transmission and access technology 8.LMDS access: Wireless communication is currently available for community broadband access, a wireless access technology 9.FTTX + LAN: mature technology and low cost way of FTTX + LAN access is the use of Ethernet technology, using fiber optic cable, twisted pair cabling communities way cable TV 2, the resource potential of our cable network though not by the national investment, but on their own developing. Than its coverage of the current telecommunication network is also extensive, has been completed 12989km national trunk cable networks have been built in many parts of the hybrid fiber and coaxial cable network, China Unicom in 22 provinces, municipalities and autonomous regions. As of the end of 1998, more than 70 million cable TV users. From the users perspective, China has the world's largest cable TV network. Currently there are two main advantages of cable networks: the last Telecommunications network formation, only to a business, that is called, the call requires only 64kHz bandwidth. Therefore, the design of the entire network will be limited to the 64kHz, including the home of the twisted pair. As a result, telecommunications networks, the Although telecommunications has taken IDSM, ADSL, the bandwidth can be done now 10MHz, 8MHz, 6MHz, but at current levels there is little room on the increase. To go any further, the cost will be very high. And CATV (cable TV) and the bandwidth of coaxial cable can easily be 800MHz, in terms of bandwidth requirements for now, CATV network's final Initially, it was used for the cable television network broadcast television transmission, that is, one-way, so to use the computer network, you must be between the existing active network equipment and front-end and the client to transform, so that it has two-way transmission capability. Overall, the cable network relative to the telecommunications network has the following advantages: - High transfer rate; - line is always smooth (do not dial-up, not busy); - multiple users of a line (including the complete TV signal) ; - do not take public telephone lines; - provides true multimedia capabilities. 3 Cable Modem 3.1 principles and use what is called the Cable Modem Cable Modem Cable Modem, also known as cable modems. It is applied in recent years as the network expanded and developed, mainly for analog signal conversion and data signals. (There is also a Power Cable Modem, is used in power cable network, not within the scope of our introduction.) Cable Modem Modem with previous data are in principle be modulated in the Cable (cable) in a frequency within the transmission, reception demodulation. The transmission mechanism and the same general Modem, the difference is that it is through a cable modem transmission frequency band of. Modem ordinary transmission medium between the user and the switch are independent, that is, the user exclusive communication medium. Cable Modem are shared media systems, other bands are still available for free cable TV signal transmission. Cable Modem solve the image due to the transmission of sound caused by obstruction, and its uplink transmission rate has reached 10Mbit / s over the downlink transmission rate higher. Modem Although the traditional transfer rate of development of 56Kbit / s products, but its theoretical transfer limit of 64Kbit / s, think of improving is unlikely. Metro Cable Modem is the key equipment set up, hybrid fiber coaxial network (HFC) backbone using optical fiber, optical node set in the district, the following optical node with a branch-type bus structure connected to the coaxial cable network users The transmission frequency of up to 550/860MHz. In the HFC network to transfer data to the terminal, the user at the need to use Cable Modem. We can see, Cable Modem is the future development of a fixture in the network, but Cable Modem is currently no international standards, the manufacturers of the product transfer rates are not the same, so the formation of high-speed broadband access is also MAN Cable Modem standards to be introduced. Note: Due to the time the editor of this term earlier, now has the appropriate international standards, the reader can check through other channels (the same). 3.2 Cable Modem Cable Modem technology principle of the analog signal from the draw down 6MHz band, the signal into a format consistent with the Ethernet protocol, and computer realization of communication. Computer users need to configure the Ethernet card and the corresponding network card driver. Coaxial cable in the 6MHz band used to provide data communications. TV and computer can be used independently of each other. RF signals between the user and the front end up or down along the coaxial cable. Sharing of uplink and downlink signal 6MHz band, but modulated at different carrier frequencies to avoid mutual interference. 3.2.1 Physical layer downstream channel in the frequency range 88MHz ~ 860MHz, the bandwidth of each channel is 6MHz, or 256QAM using 64QAM modulation, the corresponding data transfer rate of 30? 342Mbit / s or 42? 884Mbit / s. Uplink channel frequency range 5 ~ 65MHz, the bandwidth of each channel can be 200,400,800,1600,3200 kHz, using QPSK or 16QAM modulation, the corresponding data transfer rate of 320 ~ 5120Kbit / s or 640 ~ 10240Kbit / s. Bandwidth of the uplink channel according to the required data transfer rate setting. In the same bandwidth, QPSK modulation 16QAM modulation rate than low, but the anti-jamming performance, apply to the larger upstream channel noise, and 16QAM modulation for the channel quality is good and requires high-speed data transmission applications. CMTS equipment in order to reduce the interference of the uplink channel, a downlink frequency channel generally corresponds to a number of different upstream channel, CMTS device status according to the channel noise to interfere with the smaller auto hopping channel, and users have not seen the jump frequency process. 3.2.2 Media Access Control layer MAC (Media Access Control Layer) and logical link control layer LLC (Logical Link Control Layer) protocol layer provides two different signals and how users share a common bandwidth. Since there is currently no uniform industry standard, so different Cable Modem manufacturers using different protocols, the more common protocols are: the public for Ethernet CSMA / CD (Carrier Sense Multiple Access / Collision Detection, carrier multiplexing channel / collision detection) and advanced ATM (Asynchronous Transfer Mode, ATM) protocol. These agreements can effectively use the uplink channel, you can allocate bandwidth as needed to ensure the communication quality. ? 3.2.3 Cable TV front-end in the upstream direction, Cable Modem receives data packets from the computer, convert them into analog signals, transmitted to the network front-end equipment. The equipment used to separate the data signal, is converted to data packets, and send it to Internet network equipment. Meanwhile, the device can also be separated from voice (phone) signal, and transmitted to the telephone exchange. 3.3 Cable Modem system configuration, use and management of Cable Modem and the respective front-end equipment configuration is carried out. Cable Modem are used to configure the Consol interface,
paul smith shoes, can be super Win9x VT terminal or terminal program settings. Cable Modem power work, the first downlink frequency front end automatically search to find the downlink frequency, determined from the uplink downlink data channel, and front-end CMTS equipment to establish a connection and exchange of information, including the upstream level value, Dynamic Host Configuration Protocol ( DHCP) and small file transfer protocol (TFTP) server IP address. Cable Modem with online functionality, even if the user does not use, they do not cut off the power to remain with the front-end information exchange, the user may at any time on-line. Cable Modem with memory function, power on again after a power outage, the use of stored data before the power failure to exchange information with the front end, the search process can be completed quickly. Can be seen from the above, in actual use, Cable Modem generally does not require manual configuration and operation. If set, such as changing the value of the upstream level, the signal exchange process will be automatically set to the appropriate value specified on the CMTS. Cable Modem each before use, are required to register in the front, the formation of the TFTP server, a configuration file. A profile corresponding to a Cable Modem, which contains the hardware address of the device, used to identify different devices. Cable Modem hardware address indicated on the outside of the product, there are two RF and Ethernet address. TFTP server's configuration files need to address. Some products require the address of the interface by Consol be read online before. The products were labeled with an address, the address for the general address. Front-end CMTS Cable Modem is a management control device, its configuration can Consol interface or Ethernet interface. Consol interface configuration through the Cable Modem configuration similar to the way the command line one by one, and through the Ethernet interface configuration, use the special software provided by the manufacturer. Generally speaking, CMTS's downstream output level for the 110 ~ 121dBμV, received input level 44 ~ 86dBμV; Cable Modem received level range 45 ~ 75dBμV; uplink signal level is 68 ~ 118dBμV (QPSK) or 68 ~ 115dBμV (16QAM). Downlink signal transmission through the HFC network, the device port to reach the level value should meet these requirements. CMTS equipment in the uplink channel and downlink channel interface, the interface is separate from the subject to use for the high and low pass filter all the way mixed-signal, and through the mixer together with the cable TV signal into the HFC network. In actual use, can also be done simply using splitter mixed signals, but because of poor isolation of these devices, will CMTS equipment up and down within a certain line of interference between channels. CMTS and Cable Modem in the channel is established between, you can use Simple Network Management Protocol (SNMP) for network management. SNMP network management is a common procedure, for different vendors CMTS and Cable Modem equipment manufacturers need to provide management information base (MIB) file into the SNMP in order to manage the appropriate equipment. You can also use the command line approach to management, but the operation is not intuitive, prone to error. Atlas Atlas entries open more Category: Computer Technology
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