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How to deploy an ASON LH transmission network?

A global trend is currently underway in telecommunications requirement, and evidence of this trend can easily be seen by the record number of network operators that are rapidly changing from traditionally run "voice communication" systems, to more advanced "non-voice communication" systems. Nowadays, 3G, NGN and triple play are attracting more and more customers, by allowing them to experience a greater range of sophisticated, flexible and diverse services. Demand for expanded network bandwidth has increased over 100% in the past year. However, management of an extensive, traditional, low efficiency network operation has now become an even more burdensome and costly chore, especially so, when one considers that it is not able to keep pace with more advanced technologies that are quickly emerging. In other words, traditional networks are no longer competitive, when you compare them against newer and more advanced technologies that are coming on board, thus making presently run network operations more and more obsolete. Thus, the application of ASON in LH transmission has now become a major area of focus, during a period of transformation and change in global operator networks. Herein, we will illustrate the strategy of ASON deployment in LH transmission networks with an example of Chinese operator's networks.


The prospect of Chinese LH transmission networks

The rapid Urbanization progress that has been occurring in China for over the past 20 to 25 years is the result of villages that have experienced such rapid population growth in many areas of China, so that now they have been transformed into cities, teeming with diverse groups of people. The number of these types of newly emerging cities was approximately 193 in the 1980s, but they have soared to somewhere around 661 at present, including 333 regional cities. However, an imbalance in regional economical development also leads to an imbalance in the distribution of communications volume. Bandwidth distribution does not necessarily rest with the size of the population or area. Rather, such factors as, the quality of the population, cooperation between areas, and complementary energy resources, are more essential to bandwidth distribution in LH transmission network.

At present, broadband data services account for 83% of the utilized bandwidth in a LH transmission network, which is five times that of voice services. Broadband data services are mainly distributed in the more economically advanced areas of eastern and southern China, which make up 56% of the overall bandwidth demand. However, in the future an increase of 3G, NGN and IPTV services will largely depend on the per capita consumption index of cities, that is, economic power will be the driving force that instigates changes in LH transmission networks.

Figure1 Service bandwidth growth curve of Chinese LH networks

Chinese LH networks featuring as follows:

  • Flat network structure

Traditional networks, influenced by administrative division, are province-centered, with only tens of nodes in a layered structure.

At present, the emphasis of telecommunication operation has changed to metropolitan networks. The combination of city clusters and economic circles has created huge bandwidth demands, which are over-taxing and crippling regional administrative restrictions and limitations. Consequently, LH transmission networks now cover more than hundreds of cities in China, all these require a flatter and denser network.

  • Finer services

Traditional networks are designed to serve as voice trunk transmission networks, providing hop-by-hop TDM trunk circuits.

However, current transmission networks bear richer trunk services like, TDM, ATM, and packet, and even provide private line operations directly. Finer service operation not only requires an increase in resource utilization and network reliability, but also supports differential end-to-end service.

  • Network automatization

Traditional networks, with only tens of nodes and thousands of circuits, it can be managed properly by manpower.

In contrast, current transmission networks have hundreds of nodes, and more than ten thousands of circuits. Nevertheless, problems of how best to resolve dynamically increasing service demands, slow response, high-level of errors, and poor coordination of manual management, continually surface. However, as networks become more reliable, controllable, and manageable, such functions as, dynamic distribution of network resources to routes, fast end-to-end service provisioning, and automatic service protection and restoration, will become a realization for operators. Thus, maintenance and administration costs will be significantly reduced and bandwidth service operation will be supported according to actual needs.

  • Easier expansion planning

The scale of network nodes and circuits is expanding at a speed of the square of N, thus, network topology and services tend to be much more complicated. Planning network upgrade and expansion is not an easy job. In order to achieve this, operators must have the support of perfect planning software.


The status quo and technology development of ASON

ASON technology is an off-shoot of the intelligent optical network (ION), which was developed in America in 1998. In 2000, the ITU-T further advanced the concept of an automatic switched transport network (ASTN). Currently, there are only three ASON standard research organizations in operation: the ITU-T, IETF and OIF. They have respectively made a contribution to ION architecture, GMPLS signaling control, network application and network interoperability. Presently, many mainstream suppliers of optical networks provide ASON products, which are based on large-capacity SDH cross-connections and comply with international standards. There are presently more than thirty ASON networks which are in operation all over the world.

Covering the period from 2004 to 2005, through the joint efforts of standardization organizations, operators, and suppliers, many large-scale tests were carried out, which continue to furnish evidence of the unique advantages of having ASON. Some of the more obvious advantages would include: large-scale networking ability, interoperability, reliability, scalability, as well as maintainability. Meanwhile, the above mentioned tests have also prompted further research on the following topics.

  • Interoperability and its management

UNI2.0 and E-NNI standards are gradually becoming mature. For example, create/delete service requests are now launched automatically from the router/switch to the ASON nodes, and cross-manufacturer or cross-domain services are end-to-end setup quickly, as well as the Interconnectivity of the services between different operator's networks have been tested by standardization organizations. Specifications in relation to interoperability will be the next key research subject.

  • ASON is expanding to the edge of metropolitan networks

Applications of ASON in a metropolitan network would include multicast technology, interworking of GMPLS and MPLS, the combination of ASON and data service, and the private line operation of BOD and SLA. All of these have now become significant research subjects.

  • ASON is currently expanding in terms of wavelength granularities

Confronted with the problems of broadband services and insufficient SDH capacities, networks must be able to flexibly groom the transmission system of wavelength granularities. Thus, how ASON controls wavelengths will be a significant factor in future network operation.


ASON deployment strategies in LH transmission networks

During the deployment process of ASON, it is recommended to use the general strategy of, top-to-bottom, and separation-to-connection. In other words, intelligentization should be promoted from the LH backbone core network, to the edge networks. As for peer networks, separate ASON sub-networks should be deployed, according to actual needs and terrain differences. With the growth of services and the network, these separate sub-networks will be connected with the backbone core, as well as other sub-networks, to form a larger ASON network. Finally the smooth services transition and a full-ASON network will be achieved.
It is recommended to deploy the network as follows:

  • Service design and planning

In consideration of the coexistence and interconnectivity of ASON and SDH networks at the early stage, it is recommended to plan the attributes used for distinguishing services for each network separately. The combination of ASON protection and restoration functions and SDH protection mechanisms, not only allows operators to design various protection mechanisms for SLA services, but also for services between traditional networks and ASON's. After networks are upgraded so that they are able to synthesize with ASON's network on a large scale, then no damage will result when traditional services migrate to ASON networks and PC services are transformed into SPC services.

  • Project deployment and engineering

At the project deployment stage, advanced planning needs to be done in order to verify the network capacity, the working route, and the restoration path. Once this has been accomplished, then an effort needs to be made to locate and solve such problems as, complicated protection, service migration, and SCN/DCN organization, which may emerge in actual applications through systematic emulation and analog.

At the engineering stage, intelligentization needs to be carried out on a step-by-step basis. Be sure to use ASON equipment at new nodes as much as possible. Setting up ASON networks between core nodes is of the highest priority. This can be accomplished by replacing the old equipment at the non-core nodes in stages, then construct the ASON network among core nodes first, then among the non-core nodes, or use ASON equipment at these nodes. Once all of these conditions have been fulfilled, then a smooth service migration and network-wide ASON transformation should result.

  • Network OAM

ASON provides automatic service provisioning, which lightens the partial workload of service and network management personnel. And the role of service personnel changes, from being operators in charge of circuit configuration, to being decision makers of service strategies. Likewise, the role of network management personnel will be to focus more on the daily supervision of routes and the control plane.

Both networks and services run in a specified mode. Even when all pre-configured protection and restoration mechanisms fail, the purpose of enabling dynamic restoration is to further improve reliability. ASON's combination of the network management system, planning system, simulation system, resource system and expert system, will make network operation, administration, and management (OAM) much more convenient. For one thing, it ensures network security; for another, mesh restoration improves network utilization and scalability.

Figure2 Transitional solution of ASON

Viewed from the standpoint of service development, services prove to be much more dynamic with ASON. Likewise, in terms of network operation, bandwidth expansion and large-scale expansion will consequentially lead to the automatization of management and administrative roles. ASON's cutting-edge technology is the result of the most current service and network developments, but the implications and applications of this technology are much more far-reaching in scope. So much so, that now big name operators like AT&T, Vodafone and NTT, have successfully deployed their ASON networks. Huawei, which is the leading promoter and vendor of ASON, has already supplied ASON products to Telemar, CMCC Hainan, CMCC Xiamen, CMCC Urumchi and so on, which are currently in use. Through these various applications, Huawei is continuing to accumulate rich experiences in ASON planning and engineering.

As communication services continue to develop and evolve, the next generation transmission networks based on ASON will become an integral part of mainstream optical communication development and construction in the coming years.

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