How to quickly upgrade Broadband Access Network Technology

The broadband access network technology is still quite common. So I studied the structure and overall plan of the broadband access network technology. I would like to share it with you here for your reference.

Change Network Structure

A typical broadband network consists of three layers: access layer, aggregation layer, and core layer. The access layer provides multiple access methods such as XDSL to connect to various terminal devices, such as PC, IPSTB, ePhone, and IAD, and provides broadband access network technology, Internet interconnection, voice, and video services through various terminals. The Convergence layer devices converge the business flows connected to the access layer through interfaces such as FE/GE and ATM 155 to the core layer of the Metropolitan Area Network through GE/POS, and finally converge the core devices of the metropolitan area to the backbone network. The layered structure of this broadband network makes the network layers clear. The access layer provides various access methods for different users. The aggregation layer aggregates access layer business flows, and the Metropolitan Area Network core layer ensures fast forwarding.
However, in the typical tree topology broadband access network technology, for the uplink direction, there is a convergence of upstream traffic for different businesses, and the service quality of upstream traffic for various businesses needs to be ensured. For the downstream direction, as a business control point, BAS also aggregates downstream traffic of different businesses, especially when different business traffic comes from different backbone networks. In addition, the broadband access network technology may use data links at different rates, resulting in rate mismatch and transient congestion. Therefore, downstream traffic also needs to ensure service quality. Therefore, both the uplink and downlink directions of the broadband access network technology require QoS solutions.

Overall Plan

To implement QoS for broadband access, you must first make an overall QoS plan. The planning principles are as follows:
First, according to different business characteristics, service-oriented traffic distribution is implemented in the access network. Currently, the business types that can be considered can be divided into VoIP voice, video, leased line interconnection, and Internet access. In addition, it is necessary to consider that there are still management and control signals in the broadband network. Such message streams have the same QoS requirements as VoIP data streams.

Second, implement the business VLAN policy at the aggregation layer of the access network, and make reasonable bandwidth planning for the business VLAN according to the business and traffic characteristics.

Third, different customers implement different QoS: For important enterprise VPN leased lines and interconnected customers in the same city, at least implement exclusive bandwidth and independent Logical Channel (Business VLAN) at the access network aggregation layer) for personal and home users, different QoS policies can be provided for users' business types.

Fourth, different service types implement different QoS: Personal and home users' businesses are dominated by VoIP, video, and Internet access, and their business priorities are from high to low, these three types of businesses implement absolute priority scheduling policies, while Internet access businesses can be subdivided into two types of priorities in the downstream direction based on the content: internet businesses with a certain QoS guarantee and general Internet businesses without QoS guarantee, the two priorities implement weighted average scheduling policies.

QoS Introduction

QoS technology deployment includes resource control, resource isolation, resource scheduling, and other technologies and policies. Resource Control restricts the network resources used. It is mainly implemented through permit control of traffic, for example, traffic restrictions for different types and traffic priority control, resource restrictions enable reasonable proportions and distribution of different types of traffic in the network. Resource isolation ensures that different traffic does not interfere with each other. This isolation can be achieved by setting the traffic priority. The priority mainly ensures that low-priority traffic does not interfere with high-priority traffic. Resource Scheduling allocates and schedules resources. Considering the limitations of QoS maturity, the implementation and improvement of QoS is a long-term process. We recommend that you implement QoS in two phases.

Phase 1: In the early stages of broadband multi-service development, it is recommended to introduce the static QoS mechanism of 802.1D L2 priority + congestion scheduling mechanism in the broadband access network technology.
(1) define the service level based on business needs;

(2) implement business differentiation and marking policies at the edge of the network. Downstream: The business edge gateway identifies the business flow based on the IP address/quintuple. The upstream direction is distinguished and marked by the access terminal based on the physical port.

(3) The aggregation layer and broadband access network technology platform execute pre-configured QoS processing policies, such as queue scheduling and congestion processing, based on the 802.1D priority mark. In addition, the Broadband Access Network Technology Platform checks and remarks the trust level of the uplink 802.1D Layer 2 priority mark.

(4) The aggregation layer uses VLAN Technology to isolate necessary bandwidth resources. At least the bandwidth resources of the multicast service should be isolated from other bandwidth resources.

Stage 2: There are many deficiencies in the QoS mechanism of 802.1D Layer 2 priority + congestion scheduling mechanism. Therefore, with the development of broadband services, the bearer control layer must be introduced on the basis of the network layer, implement a dynamic QoS mechanism based on the call admission control technology.

Dynamic QoS Technology guarantees call-based VoIP and VoD service QoS through resource reservation and call admission control (CAC) mechanisms. In addition, dynamic QoS technology can also be used to flexibly implement user/Content-based on-demand QoS Assurance services. The basic idea is as follows:

The "brain" of the network layer is built on the network layer, that is, the bearer control layer, to control and schedule resources of key nodes (such as BRAS devices) in the network. The bearer control layer consists of two basic components: the resource management server and the user location information system. In addition, to facilitate the deployment of dynamic QoS, we also need to introduce the QoS business management platform or service server middleware in the business management layer. The QoS business management platform is mainly for non-call businesses, service Server middleware is mainly used for call-based businesses. Before using a service with QoS Assurance or creating a call-based service, the user adds the resource request and allocation process to achieve dynamic QoS Assurance for the user.

1. Analysis of multiple modes of access network technology
2. Integrated Access Network Study Notes
3. Characteristics and Solutions of Broadband Access Networks
4. Comprehensive broadband access system details
5. VDSL introduces innovations in ADSL Access Network Technology