Realize Highly Reliable PTN Ring Network Protection

With the all IP process, PTN network has gradually become the preferred carrier of Ran network with its MSTP like characteristics.The rapid increase of business volume and the gradual improvement of the standard of user experience for business fluency put forward higher requirements for the reliability of PTN network.

PTN protection technology is undoubtedly the main research direction of PTN high reliability in the industry in recent years. In the recently concluded PTN ring network test Bureau of Dongguan mobile, Huawei adopted the latest highly reliable and easy to deploy PTN full ring protection technology. This technology has the characteristics of service zero coupling, SDH like and enhanced fault location, breaks through the failure risk of multipoint protection of the original linear APS technology, realizes the separation of service layer and ring layer for the first time, and realizes the smooth migration of services in the whole network. It can be seen that the switching from APS to PTN ring network protection technology (hereinafter referred to as ring network protection) is bound to become a trend.

Thinking from point to surfaceWhile enjoying the new technology, we also calmly see that due to different business conditions, PTN network scale, architecture, site conditions, node traffic, configuration and other information vary greatly; At the same time, under the ever-changing migration scenarios, making tens of thousands of businesses transition smoothly and safely to the PTN network protected by ring network is not only a highly sophisticated process science, but also a strategic management science. Due to the deployment of the whole network, ring network protection involves the architecture, resources, capacity, service adjustment, cutover guarantee and other aspects of the whole network.Environmental complexity affects the first step of PTN ring network success

From the perspective of network architecture, PTN ring network protection is based on physical looping. In an ideal state, some areas can achieve core ring, convergence ring and access ring, while some areas can only achieve partial ring, and some stations do not meet the conditions of synthetic ring at all. Environmental conditions directly realize highly reliable PTN ring network protection. Wen / Guo Kaisun Tao determines the feasibility of the ring forming scheme and the ring forming rate. Similarly, network scale, equipment type and configuration, site type and situation, network user situation and network performance also restrict the success of PTN ring network protection scheme.

From the service point of view, the service path is tightly coupled with the traffic of the current network. For example, in the early stage of ring network design, attention must be paid to whether the link carrying capacity of the ring network can meet the switching requirements when the traffic entering the ring network increases exponentially due to the change and superposition of service paths?Smooth business migration depends on sound process guidanceThe scenarios of business migration are also different due to the current network situation. From the current situation of uneven distribution of APS, there are two cases of service migration: APS protection switching and bare service switching. The greater difficulty lies in the uncertainty of the migration process. Taking APS protection switching as an example, ideally, the migration is divided into two steps: binding the service path to the ring network and switching the service from APS working path to standby path; Then switch the service from the APS standby path to the whole network protection path.

The seemingly simple two steps need to confirm several questions: are the APS working path and protection path available? Is there a sequence of cutover business? After each switch, is the path bound to the service available?Are you sure that all services have been migrated to the new network? Is there any business interruption during the migration process? Is the environment changing Especially for the current network, there are thousands of PTN devices. Such repeated complex actions will consume a lot of human and material resources. How to deploy the business quickly and accurately is a difficult problem in reality.Precision service escort

It can be seen from the above that the complexity of the network and the changes to all levels of the current network during deployment may lead to business interruption and the resulting losses will be incalculable. Therefore, a set of end-to-end evaluation, design, implementation, verification and other processes are needed to support the reasonable planning of the ring network before deployment, smooth migration during deployment and long-term operation after deployment. At the same time, the business cutover guarantee is achieved in the delivery process, and the transition to ring network protection is safe and efficient.Precise planning, fine design, careful action comes from fine design. Before the design, we must understand and analyze the relevant information. For PTN ring network, we should first understand the network situation from all dimensions, determine whether the network meets the conditions for deploying the ring network, find and avoid the existing network problems, and design a ring network optimization scheme in line with the characteristics of the existing network, so as to minimize the impact on the existing network in the implementation process.Evaluation process: the current network evaluation process can be evaluated according to the dimension of physical equipment network architecture business layer, including architecture evaluation, equipment resource evaluation, business evaluation and protection strategy evaluation. It can quickly locate the existing problems of the current network, identify the key points of transformation, and provide data preparation and support for subsequent design schemes.

Architecture evaluation - identify imperfect networking information and key transformation points, and sort out the networking architecture required by the whole network topology and ring network; Equipment resource evaluation - collect and sort out the supporting versions that do not meet the deployment requirements of the ring network, the resources available to the ring network (slot, processing board, AIE board), bandwidth occupancy and other information; Business evaluation - understand the actual path of the business and comprehensively evaluate the business security; Protection strategy evaluation - identify businesses that need to be rectified and protection strategies that need to be adjusted.Scheme design: detailed evaluation makes fine design possible. After years of delivery accumulation and combined with the actual deployment experience in ring network protection offices such as Dongguan and Qingdao, Huawei subdivides the design into four parts: networking scheme design, service adjustment scheme design, ring network protection scheme design and upgrade cutover scheme design.Networking Scheme Design - customize reasonable network transformation schemes for different networking problems. Taking the tangent ring as an example, because of the potential safety hazard of the intersection of working path and protection path, it is necessary to focus on the transformation of double nodes into intersecting ring in the design.

Ring network protection scheme design - give the specific scheme of ring network deployment according to networking, service, protection strategy and ring forming requirements.Business adjustment scheme design - an optimization scheme based on resource evaluation and business and protection strategy evaluation. It includes the integrated design of resource allocation, business uplink adjustment, and bandwidth resource optimization and adjustment.Upgrade cutover scheme design - formulate reasonable upgrade strategy and business cutover scheme. Due to the needs of existing APS protection business cutover, the careful cutover process should be given priority in scheme design.

With the rapid deployment of E2E and smooth business migration, the biggest problem in implementing ring network protection is the huge network scale and relatively low labor efficiency. To this end, Huawei has developed the TCAT (trailcutting automatic tool) tool to realize batch deployment and cutover through the network management U2000, which improves the cutover efficiency of large networks that cannot be achieved manually to the minute level. The deployment process is generally carried out in a time period with less business volume, and the business impact time can be strictly controlled within 50ms.At the same time, in the actual ring network protection scheme, in order to achieve the smooth migration of services, we need to rely on a clear delivery process and rich experience guidance to avoid the possible cutover risk in the early stage.Solidification process, long-term operation and maintenance

After the ring network protection goes online, it is undoubtedly an important weapon to reduce the failure rate. But at the same time, reducing the operation and maintenance cost caused by new features in daily operation and maintenance must be considered. Huawei ring network protection scheme can periodically inspect and maintain the operation of ring network protection in the current network through professional methods, such as routine tool inspection, so as to find problems as soon as possible and reduce potential network risks. At the same time, excellent operation and maintenance experience will be solidified into the process in time, so that the technical ability of current network maintenance personnel can quickly reach the standard.

It can be seen that the PTN ring network protection scheme makes the network more reliable, not only because of its enhanced protection characteristics, but also includes its own effective implementation process, which not only ensures the security and efficiency of network and service migration end-to-end, but also makes the ring network protection have long-term maintenance ability and provide better guarantee for network and service.