dslam explanation DSLAM (Digital Subscriber Liner Access MulTIplexer) is defined as a digital subscriber line access multiplexer and central office equipment to complete the aggregation and distribution of ADSL access services. The data signal uploaded by the ATM DSLAM principle is implemented in the ADSL Modem through the AAL5 segmentation and assembly sublayer (SAR) function to convert MAC frames to ATM cells. After DSL modulation, the signal is transmitted to the DSLAM side of the central office The DSLAM at the central office demodulates the ADSL signal and restores it to the ATM cell format. ATM DSLAM processes many such upload signals, and multiplexes or exchanges ATM signals according to certain conditions. At the same time, classify and manage various ATM services to achieve a variety of ATM service types such as constant ratio (CBR), real-time variable rate (xt-VBR), quasi-real-time variable ratio (nrt-VBR), and variable ratio (UBR) Settings, set different flow control parameters and priority levels for different types of ATM services to ensure the support of users with different requirements for high-quality service quality QoS, and provide permanent virtual circuit (PVC) connection and upper-layer ATM The switch establishes a connection. When the signal is down, the delivered signal is transmitted to ATM DSLAM in ATM cell format. These received ATM signals carry relevant ATM information, such as ATM service type, PVC data, and other parameters. ATM identifies different business parameters and adopts different processing measures, including packet discarding principle, caching mechanism, flow control mechanism, etc., to achieve QoS guarantee for different services, and then taps into the modulation of each corresponding ADSL signal, Then output to the ADSL Modem at the opposite end. The current DSLAM is divided into ATM-DSLAM and IP-DSLAM. The main difference between the two is: ATM-DSLAM is a full-range ATM connection, while IP-DSLAM is to connect ATM to the relevant function board (Ethernet board) of the DSLAM equipment, to achieve the termination of ATM, and then convert ATM cells into Ethernet frames are transmitted. From the perspective of networking: ATM-DSLAM and IP-DSLAM are both used as access equipment, but ATM-DSLAM is an upstream ATM aggregation switch, and IP-DSLAM is an upstream three-layer switch. From the perspective of business applications: ATM-DSLAM uses PVC to implement the tunnel mechanism, security mechanism and bandwidth commitment mechanism, and the QoS performance is also good, suitable for opening VPN services. The IP DSLAM PVC is terminated at the end office equipment, IP has inherent deficiencies in data security and bandwidth control, and the QoS performance is poor, so it is more suitable for accessing Internet services. From the perspective of user authentication: ATM-DSLAM authentication is achieved by terminating PVC on the ATM broadband access server (BAS). The IP-DSLAM PVC mapping sends the VLAN identifier (ID) to the IP-BAS to authenticate the user (that is, if there is no VLAN ID sent to the upper BAS, the user cannot be authenticated). Therefore, IP DSLAM must be required to support a large number of VLANs to perform one-to-one mapping on PVC and VLAN ID and uniquely use VLAN ID to represent users. ATM DSLAM equipment is designed based on ATM's advanced technology and fully supports a variety of ATM services, such as CBR, rt-VBR, nrt-UBR, UBR, etc., providing different processing measures, different cache spaces and scheduling priorities and different for these services The level of service shaping functions, etc., enable different ATM service types to get the appropriate bandwidth and high-performance QoS support during the entire service transmission process. ATM is a connection-oriented transmission, with a natural safety isolation mechanism, both PVC, so no information leakage will occur. 2. DSLAM application When DSLAM is applied, it has a relatively simple network topology. You can choose ADSL / VDSL access according to the user's needs, networking conditions, and the range of (ADSL / VDSL) Modem twisted pair deployment from the DSLAM to the user side of the office. In addition to providing ADSL / VDSL and other access methods, DSLAM based on ATM technology also supports dedicated line services such as CES and FR, which is suitable for multi-service access applications. DSLAM as the access layer equipment converges to the ATM switch of the end office through the ATM port, and enters the ATM backbone network through the ATM switch of the metropolitan area network, providing users with Internet access and various dedicated line services. For different types of ADSL access users, DSLAM and other equipment, such as BAS (Broadband Access Server) networking, can provide flexible and variable charging methods: (1) For ordinary household users to use PPPoE to access and initiate calls to BAS, BAS cooperates with Radius server and Billing server to complete user authentication, traffic management and billing functions. (2) For SOHO users, configure PPPoA and NAT on the Modem, the entire office shares an account, and the computers in SOHO access the Internet and other services through the Modem. The Modem initiates a PPPoA call to the BAS. The service selection gateway cooperates with the Radius server and the Billing server to complete functions such as user authentication, traffic management, and billing. (3) For the connection between the company's branches and the company's headquarters, you can establish a PVC connection between the modem (configure IPoA and NAT, and charge in the form of a dedicated monthly subscription) to the company's headquarters through the ATM backbone network and the ATM switch at the aggregation layer Can access the server of the company headquarters. Above, introduced the application of ATM technology in LAN and Internet. ATM technology is an excellent transmission, switching, multiplexing, cross-connect technology. At present, ATM technology has entered practical use with a more pragmatic attitude, and the understanding of ATM technology should also be updated in thought. The sustainable development of the Internet requires ATM support to improve service quality and capacity expansion; ATM also needs the Internet to develop, apply, and display itself. As the applications that can make full use of ATM increase, the advantages of ATM are increasingly prominent. The development of the Internet is an opportunity, especially the multimedia requirements of Internet services, which will be a huge boost to ATM technology. 0.8mm Pitch 0.8mm Pitch ATKCONN ELECTRONICS CO., LTD , https://www.atkconn.com