PARTITIONING OF A COMMUNICATIONS NETWORK

Abstract: This invention relates to the partitioning of a communications network. The idea of the invention is to divide the logical connections of a communication network into several partitions, each partition representing a certain type of transmission traffic, such as access or regional traffic. The partitioning is based on simple criteria: capacity of an endpoint of a logical connection, representing a node; distance between a pair of endpoints, and traffic category representing the stability of the traffic. By using the partitioning, it is possible to separate a certain type of traffic (a certain type of logical connections) from the whole traffic picture of the network.

Description: Partitioning of a Communications Network Field of the Invention This invention relates to the partitioning of a communications network. Background of the Invention A network planning process involves several competing targets. The network should be compact and flexible to operate, and easy to expand. The network capacity and investments are planned to follow the expected transmission needs and the actual sales of transport services. There exist many alternative architectures to realize the network. The first network investment of the operator must be reasonable in size, but big enough to ensure credibility and the near future growth of the network. In other words, a certain minimum coverage of the network is needed, and the growth of the network must be secured technically and economically at the same time. Usually, these matters mean the need of building the network gradually, to add and modify network nodes and transmission lines. The changes in the network nodes can be frequent, which means repetitive additions of equipment, changes in the use of existing equipment, the increase of capacity, and adding more line interfaces. Usually, the changes also mean changes in synchronization paths and in network management channels. Problems arise when the required changes are not possible to do in the existing nodes, or they can be done, but the existing resources are not used efficiently. For example, more capacity is needed in a node and thus new equipment must be added into the node, but there is no free space inside the rack. Or the added transmission capacity is for low capacity access traffic, but the node is capable of handling high capacity regional traffic, when the node is too big and expensive to handle just access traffic. In other words, the changes and the existing equipment must match with each other. Frequent changes in the future should be taken into account. The traffic in the network can be high or low capacity traffic, and dynamic or stable traffic in relation to the time period. The objective of the invention is to alleviate the above-mentioned drawbacks. This is achieved in a way described in the claims. Summary of the Invention The idea of the invention is to divide the logical connections of a communication network into several partitions, each partition representing a certain type of transmission traffic, such as access or regional traffic. The partitioning is based on simple criteria: capacity of an endpoint of a logical connection, representing a node; distance between a pair of endpoints, and traffic category representing the stability of the traffic. By using the partitioning, it is possible to separate a certain type of traffic (a certain type of logical connections) from the whole traffic picture of the network. The partition offers a useful way for the designer of the network to decide what equipment is placed in each node, taking into account the costs and future growth. Brief Description of the Drawings In the following the invention is described in more detail by means of Figures 1 - 2 in the attached drawings where, Figure 1 illustrates different types of transmission traffic, Figure 2 illustrates the inventive method as a flow chart. Detailed Description of the Invention Figure 1 illustrates what different types of transmission traffic can be found in a communication network. The vertical axis shows the capacity demand of the traffic, and the horizontal axis shows the need of rerouting in a large physical area, i.e. the stability of the traffic. P1 represents large capacity traffic, such as optical trunk traffic. Usually the optical traffic between endpoints in the backbone trunks of a communications network is stable, i.e. there is no need for rerouting traffic in a large physical area in relation to a certain period. P2 represents traffic in a regional level (such as a city area). Capacity needs are not as high as P1 has, but the traffic is more dynamic. P3 represents low capacity traffic, such as leased cellular network traffic for small businesses. In this case the need for rerouting is very high. The starting point for the whole network plan is all desired logical connections (traffic requirements) that specify the endpoints of the logical connections, capacity of the endpoints, and the descriptive category (traffic type) of the logical connections (e.g. mobile phone traffic, interswitch traffic, data, leased line). The goal of the partition process is to divide the logical connections into separate partitions. The criteria that define a good partition are: 1. Equipment capacity is efficiently used. Not too low to get a good utilization percentage, and not too high to have some room for growth. The growth estimates are different for different types of traffic. 2. The length of routes are as short as possible. This is because longer routes require more intermediate equipment and thus increase the cost. Long routes are also more likely to be broken by some accident. 3. It is useful to separate the traffic with a certain stability from the traffic with other stabilities. Since the above criteria require that a detailed plan for the partitioning is available, it is impossible to use those criteria directly in the partitioning process. Therefore the following simpler criteria must be used: 1. The capacity of the endpoints of a logical connection in a single partition is between given limits. 2. The distances between pairs of endpoints in a single partition are between given limits. 3. A single partition contain a specific category of logical connections (traffic type). The category can be used to deduce how likely it is that the endpoints of the connection are going to change. E.g. traffic between PSTN switches in large cities is very stable and high capacity while leased line traffic used e.g. by a group of shops is likely to change. Special software can do the partition for separating the desired traffic from the logical connections. The designer chooses the capacity and distance limits, and the right category. By using the partition, it is easier for the designer to plan the network, taking into account different traffic types, equipment costs, and future growth. Figure 2 illustrates the invention as a flow chart. The input information is the logical connections of the network. The information contains all traffic demands for all kinds of traffic types. The software offers a possibility to select limits (21) for finding certain logical connections from all the logical connections. The limits are based on the above-mentioned simple criteria. After selecting the limits, the software forms two partitions (22): the primary partition which contains the logical connections inside the selected limits, i.e. the partition which is desired to be formed first, and the secondary partition, which is the rest of the logical connection outside the selected limits. The software shows (23) graphically the primary partition to the designer, who can decide if the primary partition is acceptable. If the designer wants to change the partition made, it can be repeated (24). If the designer is satisfied with the partition, a new partition from the secondary partition can be formed (25). The same steps (21 ,22,23,24) are done for the new partition: selecting limits, forming two partitions, showing the primary desired partition (the latest one) graphically, and changing the partition, if needed. The partition of the secondary partition can be repeated until all desired traffic types have been separated into the separate partitions. The last partition is the latest secondary partition, which is shown graphically (26) finally. The minimum number of partitions is two when the secondary partition is shown graphically after the primary partition is accepted. In this case new partitions from the secondary partition (25) are not required. After the partition process, the designer can route and equip the network nodes separately in each partition. The partitions are connected together for getting the whole picture of the network. The inventive software and the method offer an effective way to take into account different requirements of network planning: future growth, cost-effectiveness, reliability matters, and so on. Although, the invention is described in a way that three parameters (capacity, distance, and traffic type) are taken into account in the partitioning, it is possible to use another number of parameters, such as only two parameters: capacity and traffic type. Or it is possible to use more than three parameters for forming a desired multidimensional domain for the limits using in the partitioning. The invention is a method that can be used in many implementations and network solutions, in the scope of the inventive idea.

Claims: Claims 1. A method for partitioning a communications network containing logical connections, characterized in that the method comprises the steps of: describing the connections in a domain comprising at least two dimensions, so that the first dimension describes the capacity of the connection endpoint, and the second dimension describes the re-routing need of the connection, selecting a value range for each of the dimensions, searching for the connections which are within the selected value ranges in the domain, and forming a primary partition from the connections found. 2. A method according to claim 1, characterized in that the method further comprises the step of representing the primary partition graphically. 3. A method according to claim 1, characterized in that the method further comprises the step of forming a secondary partition, from the connections which fail to belong to the primary partition. 4. A method according to claim 1, characterized in that the method further comprises the step of changing the partition made. 5. A method according to claim 3, characterized in that the method further comprises the step of forming a new partition from the secondary partition, whereby the logical connections not belonging to the new partition form the latest secondary partition. 6. A method according to claim 5, characterized in that the method further comprises repeating the forming of a new partition from the logical connections of the latest secondary partition. 7. A method according to claim 3 or 6, characterized in that the method further comprises showing the secondary partition graphically. 8. A method according to claim 1, characterized in that the domain comprises a third dimension that describes the distance between the endpoints of the connection.

Inventors: KORPELA HARRI, NURMINEN JUKKA, KORPELA, HARRI, NURMINEN, JUKKA
Applicants: KORPELA HARRI, NOKIA NETWORKS OY, NURMINEN JUKKA, KORPELA, HARRI, NURMINEN, JUKKA
Application year: 2001
Main classification: H04L12
IPC codes: H04L12, H04Q3