Comprehensive comparison of optical fiber lines in Metro optical fiber cable networks

There are many things worth learning about in the Metro optical fiber cable network. Here we mainly introduce the comprehensive comparison of the optical fiber lines in the Metro optical fiber cable network. How to build a Metro optical fiber network? First, it should be based on the network structure of the man. Second, according to the construction idea of the man, the topology of the network should be flexible and capable of upgrading. Based on the practice of man construction in recent years, the author puts forward several design ideas for the optical cable road network of man.

Core layer optical cable line

The core layer optical cable lines are the core nodes that connect to man, such as telephone exchange bureaus, exchange bureaus, destination bureaus, mobile exchange bureaus, and core/egress routers. The number of core nodes is usually not large, but its position and function are important. It not only requires a large amount of transmission bandwidth, but also requires a large number of business types and high network survivability.

It is usually a large telephone exchange office) and an integrated service equipment installation building. It is usually located in a convenient transportation or economic and political center in a certain area. At the same time, there will be cabling cables and many major customers need to consider the routes connecting the core nodes. Therefore, the optical fiber cables connected to core nodes are generally trunk cables. Generally, the number of fiber cores of the optical fiber cables is relatively large, with hundreds of cores and hundreds or even thousands of cores. When considering the optical cable network structure of the core layer, we must consider the development of services and the evolution of the network structure according to the business status of the core node of the Metropolitan Area Network. For example, to reduce initial construction costs, the current core layer optical cable layout can be dominated by the ring network structure and virtual grid network configuration method, that is, each node has a direct Metro optical fiber cable network, the typical optical cable network structure and core are 148 cores ). In the future, we will continue to make improvements based on the actual situation to gradually implement a grid-shaped Optical Cable Network on physical routes.

The Optical Fiber Ring Network Structure of the virtual lattice network with fiber configuration method has the flexibility of rapid evolution to the lattice network, and is very suitable for quickly establishing a similar ASON Test network. However, it is only a virtual lattice network with poor survivability. If the optical cable is interrupted, multiple edges of the mesh network may be interrupted at the same time. Therefore, a mesh optical network on a physical route should be built under the conditions of conditions permit. The number of cores of the trunk cable should generally meet the needs of users for not less than five years. The total number of outgoing cores can be estimated based on the total urban demand, and then based on the user distribution, distribute each outgoing trunk cable to each bureau.

Convergence layer optical cable line

The Convergence layer of man usually has a large number of nodes and is an important business point. It is mainly used to connect the terminal board of the switch, the base station controller, the convergence router, and the leased line user. The convergence capacity is large, in addition, there are many business types, which require effective business aggregation and scheduling, reducing the bandwidth pressure on the core layer, and solving the rationality of bandwidth resource applications. Therefore, the ring network structure is recommended for the optical fiber Line Structure of the Convergence layer, supplemented by the chain network. The biggest benefit of the optical fiber ring network structure is that the reliability of optical fiber lines is greatly improved, such as line faults in section B and section C, and network interruptions in Metro optical fiber cables, it can resume communication from B to C through A, E, and D. However, the premise is that there are redundant optical fibers, but the disadvantage is that the cost is high.

The number of cores of the optical fiber cable at the convergence layer depends on the number of cores required for the active device networking at the convergence layer, that is, the number of cores required for the establishment of the MSTP business platform and data access device networking. Generally, MSTP devices on the aggregation layer must have no more than six open points, and some operators must have no more than eight open points. Generally, an aggregation transmission system is formed based on each of the five open points. Each aggregation transmission system occupies 4 cores in two directions, and each data access device belongs to two target sites based on each open point ), each opening point occupies 4 cores.

Access layer optical cable line

The optical cable line at the access layer connects to numerous terminal nodes from collection points, such as mobile base stations, remote module bureaus of switches, Data Service nodes, major customers, and important customers) the city-wide optical fiber cable network cable, need to face a variety of application users or systems, the coverage area is generally not too large, usually mainly use the star/tree structure, users who need to connect some leased line users, important users, and who have high reliability requirements can adopt a ring structure. There are three fiber configuration methods.

Direct Fiber Distribution Method with tree decline

The direct distribution method of tree decline is similar to the direct distribution method of the original audio cable, that is, the cabling cable connected to the user is directly derived from the trunk cable, and the core number of the optical cable starts from the local terminal to the remote node) decrease progressively. The direct distribution method of tree decline is suitable for areas with relatively small changes and stable user needs. The city-wide optical fiber cable network with the direct fiber distribution method in tree decline has very poor flexibility. In addition, the number of cores of the trunk cable is large, and the optical fiber resources are not shared. The utilization rate of the city-wide optical fiber cable network is low. If the node user forecast is slightly different, some nodes may have insufficient fiber cores and some nodes may have excessive fiber cores. In addition, the direct fiber configuration method with tree decline has poor survivability. In case of a fault in the trunk cable, it will affect a downstream user. In this method, the number of cores of each optical cable segment is equal to the sum of the number of cores of its downstream communication boxes.

Direct fiber configuration without decreasing tree

The direct tree distribution method and direct tree distribution method have similar structures. The number of cores of the trunk cable from the local terminal to the optical cable junction box, and from the optical fiber junction box to the optical fiber junction box is not decreasing, and the optical fiber trunk cable is derived from the optical fiber junction box.

The direct fiber configuration method with no decrease in tree shapes is suitable for areas that are subject to certain objective factors, such as insufficient pipeline resources and difficult to predict user distribution. Because the number of cores of the trunk cable from the local end to the optical fiber junction box, from the optical fiber junction box to the optical fiber junction box is not decreasing, it can immediately meet the changes in requirements along the line, the core features high compatibility. However, its trunk line is linear, and faults of upstream optical fiber lines will directly affect the survivability of downstream cables. Therefore, other optical fiber cables need to be rectified, it is also a configuration method with lower reliability. The number of Optical Fiber cores from the local terminal to the last junction box is equal to or slightly greater than the total number of fiber cores required for the junction box along the route.

Annular fiber without decreasing

The ring no-decrease Optical Fiber connecting method is the no-decrease Optical Fiber connecting method of the closed and synthetic ring of optical fiber cables. The ring no-decrease handover/configuration method provides dual-channel protection for any point on the ring. This method is suitable for high-speed or broadband businesses with a wide range of business needs and rapidly growing urban and commercial areas, it is especially suitable for large users with high reliability requirements. The annular fiber-optic method has a high flexibility and can meet unexpected customers or needs along the route at any time. In this method, the number of cores of the ring network cable is equal to the total number of cores of all the junction boxes on the ring.