After years of construction and optimization, China Mobile Metropolitan Area Transport Network based on SDH/MSTP technology has better met the transmission requirements of TDM-based voice services and a small number of data services, but the advent of 3G and full-service operations has enabled The IP-based data service becomes the main body of the metropolitan area network transmission. Although SDH/MSTP also has multi-service bearer capability, the TDM-based core makes it less efficient, more complex to configure, and less flexible and scalable when carrying IP packet services. Packet-based core-based transport technology PTN After rapid development in recent years, it has gradually matured and is expected to become the next generation mainstream technology to replace SDH. Therefore, China Mobile launched a pilot project of IP transmission project in Hangzhou Mobile to test the feasibility of PTN networking.
1. Introduction to PTN
PTN is a packet-oriented transport network and technology. It is located in the metropolitan area network convergence access layer, with packet switching as the core and provides multi-service support. It has the characteristics of data communication network networking flexibility and statistical multiplexing transmission. It also inherits the advantages of traditional optical transport network for connection, fast protection, and strong OAM capability.
PTN implements connection-oriented fast forwarding through label switching mechanism; end-to-end simulation of various non-packet services through PWE3 technology; end-to-end QoS control through DiffServ model; CIR (guaranteed bandwidth) and PIR (burst bandwidth) The mechanism implements statistical multiplexing; provides accurate frequency and time synchronization through technologies such as synchronous Ethernet, IEEE 1588v2, and ToP; provides device protection, linear multiplex section protection, MPLS Tunnel APS, LAG, and FRR, and other rich protection modes and similar SDH Carrier-class OAM capabilities. The integration of multiple technologies has laid a good foundation for PTN to carry 3G base stations and full service with high efficiency and high quality.
PTN has two technical standards of MPLS-TP and PBT in its implementation, which are derived from the improvement of MPLS technology and Ethernet technology. The Huawei PTN series equipment used in the pilot of the Hangzhou Mobile IP transmission project uses MPLS-TP technology.
2. PTN networking and protection
PTN is a brand-new equipment standard. Its working mechanism and possible business models are very different from SDH. In order to give full play to the advantages of PTN, the new PTN is more suitable for 3G and full-service competition. Zhejiang Mobile organization experts from the province discussed the networking model and protection mode of PTN in detail, and developed a better networking and protection scheme based on the deployment of OTN.
In terms of the networking model, the bandwidth demand of each access point in the 3G era may increase by more than 10 times compared with the 2G era, causing the bandwidth pressure of the core layer and the backbone layer to rise sharply. If the 10 Gbit/s ring is configured in the same manner as the SDH/MSTP network, it is easy to expand the bandwidth of the core backbone ring. The expansion cost of the ring structure is high and the flexibility is poor. Therefore, the networking model of the core layer and the backbone layer has become the focus of PTN network structure optimization considerations. The final solution is to simplify the PTN structure with OTN's high-capacity service provision and carrier-class protection capabilities.
PTN networking and deployment
As shown in Figure 1, when the PTN device is deployed, the access layer and the aggregation layer are still in a ring structure. The access layer uses the GE rate, and the aggregation layer uses the ten-gigabit Ethernet rate ring. The structure of the two-node loop prevents the single node failure risk of the aggregation node and the backbone node. Instead of building a ring system at the backbone layer, each backbone layer node is directly connected to the relevant core layer node through a GE or a 10 Gigabit Ethernet link provided by the OTN. At the same time, two large PT N devices are configured in each core equipment room, which is responsible for the access of the service port of the equipment room and the scheduling of services, and implements security sharing.
In terms of protection, the SNCP protection of the SDH network is implemented by establishing an end-to-end MPLS tunnel protection. At the same time, in order to reduce the risk of simultaneous failure of the primary and backup tunnels caused by the end-to-end protection path being too long, the backbone layer is on the OTN. The link is then superimposed with a layer of channel protection. For a 3G RNC with a GE interface, the core layer PTN device introduces LAG protection when accessing the RNC interface to avoid a large number of service interruptions caused by single interface failure.
Compared with the current SDH/MSTP network, the biggest change in the structure of the PTN is that the backbone layer and the core layer node are no longer connected through the ring structure, but are connected through a direct link. The advantage of this structure is obvious.
â— It is beneficial to the bearer-type service bearer, which greatly reduces the service punch-through cost of the PT N-node at the backbone layer and improves the utilization efficiency of the PTN node at the backbone layer.
â— The bandwidth expansion of the backbone layer becomes very simple and convenient. When the bandwidth of a certain node is insufficient, a link can be directly added through the OTN.
â— Reduced the level of business scheduling and achieved the effect of flattening the network. After the service is aggregated to the backbone node, it only needs one hop to reach the target core node, which reduces many punch-through nodes and improves the efficiency of route management.
Improve the security of your business.
3, PTN test
In order to verify the feasibility of the PTN application, we tested the PTN from various perspectives such as OAM characteristics, protection characteristics, service bearer, and clock synchronization. All major indicators met the test requirements.
We used four sets of PTN3900 and nine sets of PTN1900 to form an aggregation ring and an access ring respectively for various performance and real service loading tests. On March 25, 2009, we successfully opened the first CES service for carrying 1800MHz base stations. . At present, the service loading range has been expanded, and dozens of base station services have been opened.
The IEEE 1588v2 clock synchronization performance test is a key point of our test. Because the TDSCDMA base station has very high synchronization requirements and requires time synchronization, it can only be solved by configuring GPS for each base station. The investment cost and maintenance cost are high, and the synchronous Ethernet and IEEE 1588v2 supported by the PTN device. The protocol can better solve the problem of ground transmission with frequency and time. The test results show that the PTN equipment achieves time synchronization better, achieves the time synchronization requirement of TD-SCDMA base station 1.5μs, and the service and cell handover of the relevant TD-SCDMA base station are normal, successfully verifying the feasibility of IEEE 1588v2 technology. .
4. PTN deployment strategy
As a packetized transmission technology, PTN caters well to the development trend of future business IP and broadband. Its high-precision frequency and time synchronization transmission capability is expected to solve a big problem in TD-SCDMA construction. The performance of other aspects has also been verified in this IP transmission test. Therefore, we believe that PTN is the main solution for the next phase of China Mobile Metro Transport Network convergence layer and access layer network. Especially in the application scenarios such as 3G base station access and user data private line access, there is an advantage that SDH/MSTP cannot match. In the deployment strategy, we recommend the following.
(1) Since all the technical standards of PTN are expected to mature around 2010, the equipment of each manufacturer also needs certain perfection time. Therefore, before 2010, it is recommended to build a trial network on a small scale to understand the equipment performance, and explore the networking and maintenance experience. After 2010, the scale construction can be gradually carried out.
(2) It is expected that the TDM service will exist for a long time. The original SDH/MSTP network still has high utilization value. It is recommended to avoid replacing the original network with PTN immediately, and adopt the method of coexistence and gradual replacement of old and new networks. Network evolution. Because the working mechanism is quite different, it is not recommended to use PTN and SDH to form a loop.
(3) Considering the characteristics of broadband services in the future, it is recommended to use PTN as the access layer and aggregation layer equipment, and OTN as the backbone layer and core layer equipment to form a metropolitan transport network, which will make the PTN flatten and simplify network expansion. And business scheduling work.
(4) IEEE 1588v2 is a new synchronization technology. Although the performance has reached the test requirements, it is still to be observed whether it can truly assume the role of GPS replacement in the case of complex networks. Therefore, in the early stage of PTN network construction, TD- is still recommended. SCDMA
The base station configures GPS at the same time until the synchronization technology of the PTN is verified by the existing network to completely replace the GPS.
(5) PTN is a transmission device with packet switching as the core. The planning and maintenance ideas often need to be considered from the perspective of the data communication network. Therefore, it is necessary to avoid understanding and solving the problem from the perspective of the transmission network, especially to do well. For many IPs,
Understanding and management of address concepts such as ID.
5, the conclusion
Although PTN combines many advantages of transport networks and data networks, the evolution of any new technology is not a one-step process, and needs to be continuously explored and improved. We should closely follow the development of PTN technology and follow the principle of smooth evolution, gradually promote the application of PTN technology and the development of transport network IP to form a more efficient, secure and scalable transport network.
Transmission Line Construction unmanned aircraft systems
Transmission line dedicated unmanned aircraft the act of flying a strong and lightweight rope and attaching it to the towers, is typically performed via helicopters or by workers climbing the towers. Both these methods involve risk to both helicopter pilots and ground crews. The use of is eliminating the previously complex process consisting of several steps of reattaching the rope and decreasing the risk of injury for involved people.
This is a great proof of concept for unmanned aircraft because we proved that they can string both the outboard lines and the center line through the middle of the center phase of a tower. There are risks associated with both helicopter and tower climbing methods.
Fire Department Use Drone,Agriculture Drone Sprayer,Inspection Surveillance Mapping Drone,Cargo Quadcopter Drone
MARSHINE , https://www.puller-tensioner.com