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
Figure1 Service bandwidth growth curve of Chinese
Chinese LH networks featuring as follows:
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.
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.
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
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
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.
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
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.