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CATV Broadband Integrated Information network based on 3COM company CATV Access Network platform is a successful implementation of cable TV, data communication and network telephone "three nets in one" on the 750MHz bandwidth fiber-optic coaxial hybrid network (HFC). The open television, telephone, computer line of the public Information network, the main technical indicators to reach the world's advanced level. Now, there are 35 sets of TV programs delivered on the Internet every day, which can be used for information browsing, email, internet telephony, video-on-demand, ftp file downloading, online conferencing and other service business.
1, network goals and characteristics
The overall goal of-----network system is to build a modern communication network that covers the whole area and connects with Internet network. Taking into account the advantages of cable technology value-added benefit, which can effectively reduce the total cost of the society, lower the cost of installation and transformation of the client and the technology has been basically mature, it is decided to make use of cable modem technology to realize the "triple net integration" based on the original CATV network, and to build a unified The network can carry a variety of service types, flexible user interface and wide spectrum of access bandwidth from narrowband to broadband, and take advantage of the existing equipment and unique advantages of CATV network, by providing high speed Internet access method and appropriately developing local service in accordance with national conditions as the entry point of entering into the communication Service market, The formation of operating characteristics and create market impact, and gradually carry out a variety of communication types of integrated services, with a good performance price ratio and a variety of business integration as the characteristics of the market.
----as an operating network, it should have the following characteristics: The backbone of the network has enough bandwidth and good upgrade capability, and has the ability to carry a variety of service types, with high reliability. The access layer of the network should be highly flexible and easy to use, providing a wide range of service access capabilities. From the network management level, the network should have perfect control ability and network security, and provide flexible billing method.
Policy-based network management and performance measurement and fault monitoring based on physical, link, and network layers, and provides remote configuration and troubleshooting capabilities. In a cable modem solution, products should be in line with the MCNs standard, the head-end equipment should have flexible expansion capacity and low starting price, so as to gradually increase the network size; The client device should be user-friendly, strong cableplant adaptable and price appropriate, with good market distribution channels, In order to gradually encourage subscribers to purchase their own client devices.
2. General Design Idea
-----based on the above considerations, the construction of broadband integrated information network is carried out according to the general design idea of "three kinds of models, three layers structure, six functions and nine websites". Three modes are broadband IP network, fiber-optic coaxial hybrid network (HFC), dial-up access to three kinds of access mode. High-speed broadband IP metropolitan area Network is constructed by using single mode fiber for the units with large data flow and high degree of data requirement. The office environment is more dispersed, the data flow is not large units, as well as ordinary home users using HFC network through the cable modem one-to-one or a one-to-many way to access the network. The three-tier structure refers to the Internet, the local metropolitan area network, and the local area network. Six features are web browsing, e-mail, IP telephony, video-on-demand, FTP, and online conferencing. The nine websites include the main platform of the information port, the Government public network, the economic Info Network, the news network, the tourism network, the Civic network, the medical network, the Education Network and the Legal Service network. At the same time, as a commercial operation of the cable TV two-way network, it can not only support the traditional telephone upload mode, but also has the ability of coaxial cable duplex transmission.
-----in the face of such a complex and advanced network construction tasks, in the product selection and construction of the comparison of the project has been carefully considered. After many comparisons and actual investigation, finally chose the product performance, at home and abroad enjoy a good reputation of the 3Com company to complete the network design work and provide products. They believe that 3Com products have many important advantages, in addition to the broad product line, the rich range of products, cost-effective, technology-leading, in line with industry standards is no one can compare. 3Com u.s.robotics Cable Modem RSP is a dual-mode cable modem that can be configured by software to work in an RF reply or phone reply mode. It is designed to conform to the MCNS specification and provides a RS-232 serial port that can connect to an external dial-up modem. Since the 3Com cable solution is designed for the All-weather application of cable business operators, the average failure interval (MTBF) of the total control access platform exceeds 75,000 hours, with an average failure rate exceeding 99.98%, Fully able to meet the user's reliability requirements. In addition to these basic conditions, the total control platform strong local access capability and its high availability of telecommunications and the user-side flexible, stable 3Com built-in cable modem with the cooperation is to make users praise. The leader points out that the best combination of the total Control access platform and the 3Com built-in/external cable modem is an important reason for us to select the 3Com solution.
3, the network system design principle
----According to user needs analysis and design experience, network design ideas based on the following 4 starting point: The system in the high reliability, high-performance, highly scalable, advanced network platform to achieve unified management. The network system must be transparent, the network complexity work is borne by the information system management personnel, for the user only needs to master users ' application interface, but to the information system management personnel to provide sufficient tool support, simplifies its work, strengthens its to the network control ability. With good scalability. Always adhere to the point of view of the operation, make full use of the characteristics of cable TV station and the advantages of existing equipment, so that it transformed into a market win, fully consider the overall goal of a high starting point, multiple services, and take into account the actual characteristics of the market, so that the scheme is easy to implement
-----Specifically, the system will follow the following basic principles in the overall design:
-----1. The openness of the system
-----The wide range of CATV Information Network, the coverage, the technology and products involved, so it is very important to ensure the openness of the system. Especially in the CATV information network, the standard Cable System will be adopted. At present, cable modem technology has not been widely popularized. In this context, the emphasis on openness needs to pay attention to the following issues:
-----(1) Whether the products selected by the programme conform to existing international standards
-----(2) whether the product selected by the scheme is upgradeable and can be upgraded to the new standard after the new standard is available.
-----(3) The manufacturer's position in the corresponding product and technology field and its ability to participate in standardization.
-----2. Scalability and strategic flexibility
-----The network scale and information application are developing at an unprecedented speed, so the integration should be considered from two aspects, firstly, the expansion of scale, the increase of users and the increase of speed, which require a considerable increase in bandwidth of backbone networks, and secondly, the ability to support new applications. The further development of Internet networks will change the many lifestyles we have become accustomed to. The main conditions to achieve a unified network of multiple applications are bandwidth, strategy, end-to-end control capability and price. And these are the advantages of 3Com: Because from the edge of the network to the network core, 3CCM to provide a full range of network products and end-to-end control capabilities and network strategy; 3Com in ASIC, DSP and other chip technology advantage position makes the related equipment performance and price unification becomes possible.
----3. System security
-----to enhance the security of the system by dividing the VLAN, combining the filters, firewall functions, user authentication and VPN technology using the center, the boundary switch and the router.
-----4. Integrated network Management
----with the expansion of network scale and the increase of system complexity, network management and troubleshooting becomes more and more difficult. This program will provide advanced and complete network management tools.
-----5. Advanced and mature of equipment
----The world today, the development of communication technology and computer technology is changing rapidly. The design plan should be adapted to the trend of new technology development, both the technical maturity and the advanced nature of the system.
4. Network design Scheme
----1. Backbone Network
-----make use of existing optical fiber network, HFC network and supporting telephone network to build a metropolitan area network connecting all units of the city (including Campus network), stand-alone and home users. For each unit of LAN, can be used in two-way HFC network cable modulation and demodulation technology to achieve the interconnection of the local network. Single/bidirectional HFC network is used as far as possible for single or home users to obtain high bandwidth and low cost Internet connection. For a one-way HFC network users must be connected to the Internet using the telephone uplink. For remote LANs that cannot be connected via fibre or HFC, access can be achieved through routers and telecommunications department DDN, X.25, or Frame Relay networks.
The core of the-----backbone is the 3Com corebuilder 3500 third-layer high function switch. It dramatically improves the performance and performance/price ratios of high-end switching and routing devices. Relies on sophisticated third-generation ASIC technology, which provides the second and third-tier communication capabilities of the wire speed. At the same time, because of the use of the most advanced policy-based service mechanism, the switch can support real-time multimedia network communication. Coupled with support for VLANs, multicast, multi-protocol routing, and Network management (including Rmon and roaming analysis ports), Corebuilder 3500 provides a reliable and flexible network infrastructure that can be used as a backbone network to provide a third-tier forwarding capability by devices, Instead of a traditional router in the LAN, it can also be used as an edge device to access Gigabit Ethernet or ATM networks.
----2. Connection to the Internet
The-----is connected to the Internet via a 3Com superstack II netbuilder si router with high-performance, secure, support for virtual private networks and built-in firewalls.
----3.Cable Modem Access System
----(1). Headend (head end) system
The key points of the-----access layer are configuration flexibility, better performance price ratio, scalability, manageability, especially access policy management and access control capabilities management, and remote configuration and troubleshooting capabilities.
The main transmission medium of the-----cable system is a bidirectional HFC network, which is mainly composed of two-way amplifier modules such as the positive and negative optical transceiver of the optical fiber network and the coaxial cable network.
-----in the first phase, it is planned to configure the head-end devices (CMTS) of the 2 cable access systems at the hub node. Each device provides 1-channel downlink and 2-way channel, 2 CMTS can provide 2-channel downlink and 4-way channel. The highest data rate for each downlink channel is 38Mbps, and each uplink channel has a maximum speed of 10Mbps. The initial downlink transmission frequency setting is considered far away from the TV channel, for example in 650-750mhz, and the uplink transmission frequency is set at 5-65mhz (actually used in 20-42mhz).
-----selection of 3Com cable access products CMTS is based on the world's most popular remote access Concentrator brand total control. This telecom-grade product can serve as a unified platform for both the CMTS and TRAC systems (phone-back systems), providing a complete two-way and phone-response system solution for users on a single, compact and reliable platform.
----Modular structure allows users to easily expand the total control function, only to the chassis to add a board card. And by separating the CMTS from the TRAC function in a large device, it is easy to scale the system without causing a loss of performance.
The-----head-end device is 16 slots and can be configured with 4 to 6 downlink and 8-way channels, and can be grouped according to the different needs of the number of channels based on flexible modular design.
-----Each cable modem front-end connects to the backbone via a 100Mbps port connected to the Corebuilder 3500 LAN switch 100Mbps port in the edge switch.
-----Business opened, with the increase in the number of users, you can consider adding data channels, or in each of the optical transceiver to configure the head of the device, the head of the device through the 100Mbps Ethernet dedicated fiber to connect to the backbone node.
-----3COM Cable Modem termination System (CMTS) provides a high-speed modular architecture with a backplane capacity exceeding 1Gbps. CMTS allows cable operators to establish high-density and highly adjustable termination systems for their data-over-cable (DoC) services. The core module of CMTS is cable Access Router, which provides routing connections from the Internet or from the internal backbone data network to the RF (CATV) network. By working in conjunction with the QAM modulator (downlink module), if output can be provided in a 6MHz and MCNS compatible cable data channel. Dual Mode (64/256) QAM modulation makes the downlink data transfer rate up to 38Mbps. The uplink channel is provided by the QPSK/QAM Demodulator card (uplink module) and each uplink channel supports a maximum 10Mbps rate (depending on the encoding method). Connections to the local area network are provided by one or more 10/100base-t Ethernet ports.
-----Users can integrate dial-up access in CMTS devices and provide richer Internet services and secure services such as DHCP address assignment and user authentication through the Edge Server Pro module based on NT systems.
-----(2). Client Side
-----User Cable Modem choice, in addition to meet the MCNS standard, client devices should be user-friendly, strong adaptability, and the price is appropriate, with good market distribution channels, so that subscribers can gradually encourage their own purchase of client equipment.
----in the scheme, 3COM's external cable modem (Cable modem RSP) was selected. This product can be connected to any cable system, either in a radio-frequency response (bidirectional) or in conjunction with a stand-alone dial-up modem to work on a telephone reply. Built-in security features and protocol filtering ensure the confidentiality of user data, while tiered service levels (including delegated information ratings) enable differentiated services.
-----4. Network System Management
-----Run such a large and complex network, must adopt advanced management system. To reduce the growing burden of central management consoles, LAN and WAN links, and management information system personnel, the traditional centralized network management model must have a fundamental change. The 3Com solution is to provide distributed information and intelligence across the network, making network management more automatic, and making basic decisions at or near the source of the fault. In the broadband Integrated information Network, the 3Com new generation of management software transcend Enterprise Manager is adopted, and the software has realized the distributed network management mode.
-----As the industry's leading network management tool, 3Com transcend Enterprise Manager has the following features: the integration of the most advanced network administration capabilities in the most advanced network equipment, All 3Com network equipment has advanced Smartagent network Management Intelligent Agent, its unique design makes network management will not degrade the performance of the network almost. and smartagent can continuously expand the management intelligence of the equipment through the software upgrade, and extend the inherent capability of the industrial standard management platform, transcend Enterprise Manager is built on the industrial standard management platform, including Sun Netmanager, HP OpenView, IBM NetView, Novell NMS and Microsoft Windows and NT. Provides a series of integrated management application tools, focusing on providing solutions to practical problems, transcend is committed to providing network managers with practical management tools to solve practical problems.
-----3Com Transcend Enterpreise Manager also implements the management of cable modem access system well. The CMTS is built with extensive network management support and includes a full range of SNMP MIB, including Mibii, Mcnsrfi, and Mcnstrimib. The system can be managed locally or through a remote rf/dial-up connection. The 3Com cable Data network management solution incorporates the 3COM transcend management and custom SNMP applications to manage the DOC network. These management systems work together to provide comprehensive information about the network's operational status. The 3COM management structure is based on the combination of distributed transcend software Intelligence and transcendenterprise monitor hardware probes. The Windows based management platform employs a 3Com graphical management application, which provides data flow monitoring and control in a global scope. Users can also choose to perform advanced applications to optimize configuration, troubleshooting, and performance tuning for 3Com systems.
The management of the-----Access system also applies two important manager Cable Headend Manager (CHM) and cable Modem Manager (CMM), both of which provide custom management. These two managers can be run as stand-alone applications or in conjunction with 3COM transcend management software.
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