Broadband access network technology is still facing challenges

It is very useful to understand the mechanisms of Broadband Access Network Technology and enrich our professional knowledge. Here I will give you a detailed explanation of these mechanisms, so that you can better understand the broadband access network technology. As telecom operators want to provide real-time video and audio services on IP networks, especially in broadband access networks, bandwidth is relatively limited due to cost factors, resulting in QoS requirements. However, the deployment of QoS solutions on the entire broadband access network requires adjustment and reconfiguration of the entire network, which is highly complicated, qoS, which supports multiple services, is still a challenge.

At present, few telecom operators have implemented a complete QoS solution based on Differentiated Services in the broadband access network. Because the end-to-end QoS indicators are allocated to several IPOD, the broadband access network needs to interact and coordinate with other IPOD network resources. Broadband access networks also need to support SLA and provide SLA monitoring, network management, and operation mechanisms.

Broadband man QoS Mechanism
Metropolitan area networks generally use optical network technology, which can be based on packet switching, circuit switching, or combination of the two. MSTP is a new generation SDH device. In addition to circuit switching, MSTP provides two-layer, Layer 2, or Layer 3 data exchange capabilities, enabling the device to have two capabilities: Circuit Switching and data exchange. Among them, the Multi-Protocol Label Switching (MPLS) technology organically combines the layer-3 technology (such as IP routing) with the layer-2 technology (such as ATM, FR, the so-called layer-4 switching technology enables MSTP to have many performance advantages and provides real-time services with high QoS requirements. It has become one of the key technologies supporting broadband MAN. In the design of the QoS scheme for broadband access networks, we should consider the cooperation with the mpls mechanism of the mstp network and the ing between the two. Obviously, a unified MPLS mechanism can simplify the QoS scheme.

RPR combines the advantages of Ethernet and SDH and defines an independent physical layer-the access control layer of the elastic grouping ring media. It solves the problem of multi-service transmission in the ring technology widely used in man networks. RPR technology uses high-speed hardware technology and tag switching technology to process data packets. It determines how to forward (queue and Schedule) or discard the packets based on the CoS Domain value of the accepted grouping header, supports policy-based shaping and control, and uses the SLA mechanism to determine the promised information rate (CIR), burst Information Rate (BIR), and maximum burst size. Based on the above QoS mechanism, RPR claims to be able to provide voice quality TDM circuit services, as well as provide certain QoS guarantees for real-time and non-real-time variable bit rate businesses, and try to forward as much as possible for businesses. The QoS mechanism of RPR technology is different from the existing QoS mechanism of broadband access networks, but the QoS mechanism is similar. In the joint design of QoS schemes, the ing and cooperation between the two are mainly considered.

Because the man and the access network can adopt different methods to ensure service quality, and different QoS schemes are used, the communication management between the access network and the man needs to cooperate, negotiate a Service Level Agreement (SLA.

Broadband access network technical QoS Mechanism
The QoS of the connected network has its own special complexity: on the one hand, the bandwidth of the access network is usually limited, and on the other hand, the access network is complex, involving multiple technologies, such as Ethernet, ATM, FR, etc; multiple types of business aggregation, such as video, audio, and data.

In the typical tree topology broadband access network technology, uplink traffic is converged. Uplink traffic usually has strict service quality requirements. Therefore, the broadband access network must ensure the service quality of upstream traffic for various services. If the downstream traffic of the broadband access network technology only comes from one backbone network, the downstream traffic will not converge. However, when the communication flow of the broadband access network may come from different networks (telephone exchange network, IP backbone network, and television network), or even from multiple networks of the same type, this will inevitably cause convergence of certain types of service streams in the broadband access network. In addition, the broadband access network may use data links at different rates, resulting in rate mismatch and transient congestion. Therefore, we also need to ensure the quality of service for downstream traffic.

Because of the different physical media, two different types of broadband access network technologies are generated: one is a frequency band system using carrier-modulated frequency-division multiplexing technology, such as ADSL and HFC; the other is the baseband system, which adopts the baseband binary encoding mechanism, such as the usual PON network and Ethernet network.

Different technologies make it difficult for different access technology QoS solutions. ADSL and HFCs use the frequency division multiplexing technology, and some services are provided to dedicated bandwidth. These services do not interfere with each other, reducing the complexity of QoS solutions. For example, the telephone and data services in the data service between the data service and the TV service or between the telephone service and the data service in the ADSL Network occupy different spectrum, and different services of a user do not interfere with each other. However, it is more difficult to ensure the service quality of multiple businesses by adopting the statistics Reuse Technology in the broadband access network technology and sharing the bandwidth of the entire Link of various businesses.

There are two methods to ensure service quality in the IP packet switching network. The first method is the application-level service quality mechanism, which does not change the network architecture. By modifying the application-level implementation, they can better adapt to network conditions, that is, changes such as latency and packet loss rate, such as the error correction codec mechanism, forward correction FEC, and new transport layer protocols such as real-time transmission protocol/Real-time Control Protocol RTP/RTCP. The second method is to modify the network mechanism to ensure the service quality. It mainly involves the service quality framework, scheduling mechanism, Cache Management Mechanism, broadband access network technology, and traffic adjustment mechanism.

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