background knowledge
users can access IP networks on the access server by utility telephone network, implement remote access Internet, dial-up virtual Network (VPDN), build network applications such as Internet Enterprise Internal Intranet. Access servers can process authentication, authorization, and billing (AAA), and tunnel IP packets that are ISP routers, which can form an ISP local service site with the web server, AAA server, DNS server, router, and related supporting devices. Typically 60-ports (including 60 ports) for small access servers, 60 to 480 ports for medium-sized access servers, 480 to 2880 ports of large-scale access servers, 2880 ports or super large access servers.
Features and Applications
1.Internet Access
Dial-up Access is the most widely used netwit network, now Some modem functions allow users to receive both third-party calls during Internet browsing, but also keep and connect relationships with local MODEMs. And the basic rate of interface BRI users use 2B + D pathway, which is the highest access rate reaches 128kbit / s Internet. It is more advantages to all aspects by simulating the MODEM Internet, including faster connection speed 1s, stable Relatively high speed access rate, rich supplementary business, etc. Enterprise users can use a telephone line or a specialline online, which is an important application supported by the access server. It provides an interface including the V.35 proposed interface for connecting frame relays and dedicated line interfaces.
2. Support multi-link bundle
multi-link bundled protocol MultiLink PPP is used to bundle multiple physical links in the PPP, Improve and use higher bandwidth. Multi-link PPP protocol is a protocol for multiple links, splits, sequential transmission, and recombination PPP packages between two systems. The MP bundle inside the access server includes two B bundles and two modem bundles, and a binding of B and a MODEM. The access server can support analog-analog link bundle, analog-digital link bundle, digital-digital link bundle, ISDN 30b + D link bundle.
3. Provide E1 interface
to support China No. 1, No.7 signaling (including TUP, ISUP signaling), ISDN PRI signaling, etc. A variety of inter-office relay signaling. NO.7 signaling is one of the basic requirements of the current access server function, and the access server can be connected to the telecommunications network using the signaling relay by the telecommunications bureau's local PCM transmission system. Since NO.7 signaling management PCM transmission system supports data service transmission, it greatly supports data exchange between users PC and Internet.
4. Secondary Compound Function
Tact Composition Function Refers to the access server to handle different named numbers from the same trunk group (corresponding With different ISPs), the relay inclusion is suitable for multiple ISP sharing the same access server, and its functions are pointed out of the called number discriminating, different IP address assignments, and different access authentication systems. The access server can support multiple access numbers to access in the same trunk group, supporting PSTN and ISDN users to access in the same trunk group, and the access number is the same.
5. Firewall Features
The firewall function of the access server can use IP Filter and Two ways of IP Pool are available. The IP Filter mode is the filter function of the access server to provide the IP package, providing different levels of IP package filtering function to users of different privileges, achieving accessibility of different users; IP POOL method is to fit the firewall with the corresponding router Function, the access server reads the IP address from different IP addresses according to the user's authorization to the corresponding user, as the caller IP address of the user.
6. Access authentication, authorization and billing function
Access server is the initiator of the user access authentication request, which receives from the user Enter the authentication server user authentication response, and accordingly, the permission to request the user's access and start charging. After the user access authentication is passed, the access server starts billing. User normal modem is disassembled or abnormal modem to remove the line, the access server is stopped, and the difference between the billing time and the starting time is time long. For users accessible, access servers can charge according to traffic.
7. Network management function
Access server accepts the management of IP network management, Implement network management functions such as configuration management, performance management, fault management, security management, accounting management. The network management agent module is set in the access server, the network management agent module implements communication with network management, collecting the corresponding information of the network access server and maintains the MIB library. The communication protocol usually used is SNMP. Configuration management of the access server can be implemented by telnet. NMS for user calls, user calls cannot be connected, the average time of user access, the average fee, idle probability, busy probability, average user curve, monthly user curve, equipment element failure probability, unable to remove Statistics for the number, abnormal termination causes and frequencies.
8.ip Phone Features
Provide IP phone features, including Click to Dial Click Dial, Click to Fax Click Fax, Email Indication, IP Fax, IP voice mailbox and Call Center and other functions.
9. Caller ID function
When the dial-up user has worked in the IP network, the caller ID requires the access server to receive the caller, processing Called messages and send out the electrical instructions to the user.
10. Repayment function
User dials into the access server and passes the authentication, if the user applies for this function, access The server will automatically disconnect the call and call the user. After the call connection is established, the user can realize the Internet.
11. Virtual Dial-up VPDN Features
The VPDN feature in the access server includes user qualifications for dial-up users requested to establish a virtual data network. Certification, and tunnels, packet transfer, and demolition tunnels for establishing virtual data traveled through qualified users. Access Server Use VPN technology to implement a variety of new services, and enterprises can apply for VPN services in one place to use VPN services elsewhere. When the user is dial into the local ISP access server, the corresponding service can be enjoyed even if there is no ISP account.
12. Build an internal intranet network
user can access the access server through the remote dial or router, authorization, certification and billing The server is verified to achieve access to the intranet of the enterprise. Among them, the remote branches can be internetized by telephone lines or dedicated lines, and SOHO users are online or dedicated.
13. Data Bypass Function
Enter the server can be used as a new module for new independent biodiends or large digital switches, thereby making digital program-controlled switches remotely The function of accessing the IP telephone gateway. Thus, the data user of this Council can directly access the data network through the internal communication mode of the large digital program switch, no longer occupying the relay resource, reducing the blockage caused by the Internet call in the telecommunications network, and implement data bypass function.
14. Device Management Function
Access server has a remote dial-in function, remote dial terminal or local console can be restored in access server failure Rear start; you can modify the functionality of the user bill, add user bills or revoke user bills; device security control management, modify user identity (PIN), forcibly dismantle the connection; you can implement the fault location of the device, Determine the faulty MODEM and stop using it to implement maintenance and monitoring of the access server.
Development trends
From the market's requirements for access servers, the telecommunications-level operating products are in its high stability, high reliability, flexible expansion and upgrade, large The characteristics of capacity, high integration will remain favored by users.
From the technical point of view, NO.7 signaling in the access server has become a basic functional requirement. NO.7 signaling is due to rich business functions, high efficiency, fast connection speed, fast network flexibility, and advanced, universal public channel signaling, will also dominate in PSTN / ISDN.
In operation, management and maintenance and security, a larger centralized network management feature will become a higher demand for the market to access servers. It requires network management capabilities not only manages information on one side of the data device, but also manages information on the phone network.
The flourishing of data services, the fusion of data and voice services and other services will put forward higher requirements for the development of future access servers, so the multi-service access platform is also a future access server. The trend of development.
At present, my country's broadband access market has begun to start large-scale startup, and each operator is in this area. Due to the increasing increase in dial-up and ISDN Internet users, the access server that can make full playback of telephone network exchange potential will still be available.