Control costs and resolve enterprise ADSL business applications

Asypolicric Digital Subscriber Line (ADSL) is a high-speed user access method that connects to CHINANET in the Chinese public multimedia communication network through ADSL, it is a technology that provides broadband data services through common copper-core telephone lines. ADSL uses existing twisted-pair copper wires (common telephone lines). The above and downlink asymmetric transmission rates are connected to the Internet, and the uplink transmission from the user to the network is low speed, up to 1 Mbps; downlink from network to user) is high-speed transmission, up to 8 Mbps, 1 shown. ADSL currently provides two access modes: virtual dial-up access and leased line access, it features convenient and fast installation, exclusive bandwidth, Internet access, and non-interference between calls. The ADSL virtual dial-up access service is a broadband Internet access method for home users and small and medium-sized enterprise users, it is applicable to both centralized user access and distributed user access. The ADSL leased line access service is intended for commercial users such as Internet cafes and small and medium-sized enterprise users.

Figure 1 ADSL graphical Definition

Using ADSL, We can browse WWW webpages, chat online, play online games, send and receive emails, download files, and so on, and access the broadband multimedia information network at a high speed, enjoy a variety of broadband multimedia services such as VOD, online 3D games, online TVs, online shopping, e-commerce, telemedicine, and distance education. ADSL has a wide range of user groups, such as home office SOHO and remote office ROBO), high-speed Internet access, distance education, remote medical care, VOD, video conferencing, and interconnection between networks, 2.

Figure 2 ADSL User Group

2. Three methods for implementing secure broadband Internet access for enterprises using ADSL

1. Small and medium-sized enterprises use the broadband on the ADSL Router

Enterprise broadband Internet applications have diverse needs and are cost-sensitive. Using ADSL Broadband Security routers and switches can meet the Internet access requirements of enterprise users and provide reliable, secure, and easy-to-maintain efficient Internet access means. These methods include: the proxy server and DHCP server are completed by the ADSL router and switch, saving the cost of purchasing the computer; the quality of the ADSL router and switch is stable, and the communication company can remotely configure, diagnose, and repair the server; security Control and QoS management are supported to effectively prevent malicious attacks by network hackers. NAT Network Address Translation and plug-and-play are supported without the support of on-site technical personnel. browser configuration is supported; when there is no network traffic, the system automatically goes offline. The network must be connected as long as the normal working light of the line is on, and the network monitoring is simple and intuitive.

Figure 3 broadband Internet access for small and medium-sized enterprises

2. Establish network access for small and medium-sized enterprises through ADSL + VPN

Assume that an adsl lan enterprise user has four fixed static IP addresses, and an enterprise applying for access to the adsl lan can set up a company's website on the Chinese public multimedia network, provides WWW, FTP, E-mail, and other services. The ADSL service has sufficient bandwidth for LAN users to share. Users can provide Internet services to LAN users of the entire Organization through proxy servers. Because ADSL is based on the ATM asynchronous transmission mode) optical fiber transmission is connected to the Internet, it can also provide an ATM-based VPN Virtual Private Network) service.

To achieve VPN connection, a VPN Server Based on Windows 2000/2003 Server must be deployed in the internal network of the enterprise. The VPN Server connects to the internal private network of the enterprise and the Internet, therefore, the VPN Server must have a public IP address. When a client communicates with a computer in a private network through a VPN connection, the ISPInternet service provider first transmits all the data to the VPN Server, then, the VPN Server is responsible for transmitting all the data to the target computer.

Advantages of using ADSL + VPN access:

1) reduced costs: first, remote users can log on to the Internet by applying for an account from the local ISP, using the Internet as a channel to connect to the private network within the enterprise, greatly reducing communication costs. Second, enterprises can save on the cost of purchasing and maintaining communication equipment.
2) enhanced security: VPN uses three technologies to ensure communication security: Channel Protocol, authentication, and data encryption. The client sends a request to the VPN Server. The VPN Server responds to the request and sends an identity question to the client. The client sends the encrypted response information to the VPN Server. The VPN Server checks the response based on the user database, if the account is valid, the VPN Server checks whether the user has the permission for remote access. if the user has the permission for remote access, the VPN Server accepts the connection. The client and server public keys generated during authentication are used to encrypt data.
3) supports the most common network protocols: clients in the network based on the IP, IPX, and NetBUI protocols can easily use VPN.
4) benefits to IP address security: VPN is encrypted. When VPN data is transmitted over the Internet, users on the Internet can only see public IP addresses, but cannot see private network addresses contained in the packets.

3. Set up network access for small and medium-sized enterprises through ADSL + VLAN

Internet access through ADSL and Internet access through proxy server. The main device of the network is a 24-port network switch. For example, the enterprise's sales department, Administrative Department, Financial Department, and technical department's PC and proxy server are connected to the smart switch, in addition, it is assigned to its respective VLANs and configured through VLANs to isolate unnecessary information communication between CIDR blocks. As a result, other departments are unable to access the financial system of the financial department. The important business data of the Marketing Department also avoids the entry of other departments, thus improving the security of network networking.

This application solution has two advantages: simple architecture and easy maintenance. It adopts the ACL and VLAN technology to enhance network security. This practical solution requires three basic functions: to enable all office PCs in an enterprise to access the Internet, send and receive E-mail, and access enterprise-level application servers; the second is to ensure that all functional departments have independent and secure subnet systems and do not intrude into each other from the aspect of enterprise operation security; third, some PCs in each department can be set as servers that can access other subnet systems according to their functional requirements to share office resources.

Iii. Load Balancing of multiple WAN ports using ADSL

The so-called WAN port is the interface connecting the router and WAN. In the past, multi-WAN port technology was mainly used in mid-and high-end network products. However, with the demand of low-end users for multi-WAN applications, the market saw a Broadband Router that supports multiple WAN ports.

Traditional Internet cafes and small and medium-sized enterprises have only one WAN exit. All computers connect to the Internet through this WAN port. On the one hand, the ADSL line is cheap, but the speed is only kb or 1 Mb, when all clients access the Internet, the speed is very slow. If you rent a leased line or optical fiber with a higher bandwidth, the cost is quite high. At this time, the role of the Multi-or dual-WAN-port Broadband Router is apparent. On the other hand, ADSL is subject to high line interference, and frequent disconnection occurs. If we use a multi-Wan port Broadband Router, connect multiple WAN ports of the router to different ADSL lines, this effectively avoids the disconnection problem. When one ADSL line is disconnected, the other ADSL will undertake all data transmission work immediately.

In the process of using the network, the services provided by different ISPs are different, and the intercommunication speed is very slow, for example, access the site of China Netcom from china telecom lines or browse the FTP of China Telecom from China Netcom network only a few KB. How can we solve the problem of ISP mutual access? The simplest method is to use a Broadband Router with multiple WAN ports to connect one China Telecom line and one China Netcom line in turn, then, through the simple configuration of the router, the speed of access to which ISP can be greatly improved by computers in the network.

From the above introduction, we can see that for small and medium-sized enterprises and Internet cafe networks, the characteristics of their application of multi-Wan port routing equipment are ---- two or more network outlets, the two network outlets are equivalent, this improves the speed while ensuring the stability of network connections, and achieves Load Balancing for multiple WAN ports, this allows network managers to enjoy the most efficient network performance with the least money. Therefore, load balancing using ADSL and multi-WAN broadband routers is favored by small and medium-sized enterprises.

4. Use ADSL to back up optical fiber lines

Among the many Internet access methods, small and medium-sized enterprises usually choose optical fiber access or ADSL Network Access. Fiber access is an ideal access method. However, ADSL Network Access is a network access solution widely used by small and medium-sized enterprises.

Because the initial cost of optical fiber access is relatively high, users need to purchase a pair of optical/electrical conversion devices (commonly known as optical cat) during access. The optical fiber laying process is time-consuming and cannot be withdrawn once the cost is invested. In addition, the cost is relatively high, and the payment is generally based on monthly rent. However, ADSL access can be directly modified on the existing telephone line, without modifying the signal transmission line, without punching through the wall and laying another cable, and using the common copper telephone line as the transmission medium, you only need a dedicated Modem to achieve high-speed data transmission. In addition, the cost is relatively low, and various payment methods are available. The main cost in the early stage is ADSL Modem. Therefore, in order to save money, enterprises can apply for multiple ADSL lines from different telecom operators, so that multiple ADSL connections can be used as optical fiber backup.

At present, the broadband access method for small and medium-sized enterprises or Internet cafes may have access to one optical fiber and multiple ADSL lines at the same time. When we use multi-Wan port routing equipment, it can provide enterprise users with a hybrid access of up to four ADSL/optical fiber cables, and provide a high-performance solution for the structure requiring multi-line access in the new situation, multiple ADSL connections are used as optical fiber backups. Due to the backup line method, the device must be able to automatically monitor the working status of the device. when the line is interrupted, the backup device and the backup line are automatically used for automatic backup. The special technology of adsl vpn can detect the working status of the main line in a timely manner. When the optical line is interrupted, the adsl vpn is automatically activated to realize remote data exchange, this enables automatic backup of optical fiber lines.