computer science crazy|
Joined: Dec 2008
17-09-2009, 01:12 AM
According to the San Francisco-based market research and consulting firm, Internet traffic will have reached 350,000 Terabytes per month as we pass into the new millennium. This is a significant milestone, as it indicates that data has already surpassed the voice network. To keep pace with seemingly insatiable demand for higher-speed access, a huge, complex, network-building process is beginning. Decisions made by network Architects today will have an immense impact on the future profitability, flexibility, and competitiveness of network operators. Despite the dominance of synchronous optical network (SONET), a transport technology based on time division multiplexing (TDM), more and more operators consider adopting a point-to-point strategy and eventual mesh topology. This article highlights the key advantages of this new approach.
With such strong demand for wideband access - 1.5 million house holds already have cable or digital subscriber line (DSL) modern capable of operating at 1 Mbps - there is no doubt that the future for service providers is extremely bright. However, there are a number of more immediate challenges that must be addressed. At the top of the list is the fact they network investments must be made before revenues are realized. As a result, there is a need for less complex and more efficient network builds. In an effort to cut network costs, action is being taken across several fronts: consolidating network elements, boosting reliability, reducing component system costs, and slashing operational costs. As far as optical networks are concerned, the action likely to made the most positive impact is the development of new network architectures, such as point-to-point/mesh designs. Ring architectures will still be supported, but new Internet protocol (IP) and asynchronous transfer mode (ATM) networks will find that mesh, with its well- defined optical nodes, lends itself to robust optical rerouting schemes
POINT-TO-POINT OR MESH TOPOLOGIES IN THE METRO OPTICAL NETWORK
According to point-to-point topology, one node connects directly to another node. Mesh is a network architecture that improves on point-to-point topology by providing each node with a dedicated connection to every other node.
This article highlights the key advantages of adopting a point-to-point strategy and eventual mesh topology, a new approach in transport technology.
It is the method of arranging various devices in a network. Depending on the way in which the devices are interlinked to each other, topologies are classified into:-
Of the above mentioned types, the most popular & advantageous is the mesh topology.
Governments are keen to encourage the roll-out of broadband interactive multimedia services to business and residential customers because they recognise the economic benefits of e-commerce, information and entertainment. Digital cable networks can provide a compelling combination of simultaneous services including broadcast TV, VOD, fast Internet and telephony. Residential customers are likely to be increasingly attracted to these bundles as the cost can be lower than for separate provision. Cable networks have therefore been implemented or upgraded to digital in many urban areas in the developed countries.
ADSL has been developed by telcos to allow on-demand delivery via copper pairs. A bundle comparable to cable can be provided if ADSL is combined with PSTN telephony and satellite or terrestrial broadcast TV services but incumbant telcos have been slow to roll it out and 'unbundling' has not proved successful so far. Some telcos have been accused of restricting ADSL performance and keeping prices high to protect their existing business revenues. Prices have recently fallen but even now the ADSL (and SDSL) offerings are primarily targeted at provision of fast (but contended) Internet services for SME and SOHO customers. This slow progress (which is partly due to the unfavourable economic climate) has also allowed cable companies to move slowly.
A significant proportion of customers in suburban and semi-rural areas will only be able to have ADSL at lower rates because of the attenuation caused by the longer copper drops. One solution is to take fibre out to street cabinets equipped for VDSL but this is expensive, even where ducts are already available.
Network operators and service providers are increasingly beset by a wave of technologies that could potentially close the gap between their fibre trunk networks and a client base that is all too anxious for the industry to accelerate the rollout of broadband. While the established vendors of copper-based DSL and fibre-based cable are finding new business, many start-up operators, discouraged by the high cost of entry into wired markets, have been looking to evolving wireless radio and laser options.
One relatively late entrant into this competitive mire is mesh radio, a technology that has quietly emerged to become a potential holder of the title 'next big thing'. Mesh Radio is a new approach to Broadband Fixed Wireless Access (BFWA) that avoids the limitations of point to multi-point delivery. It could provide a cheaper '3rd Way' to implement residential broadband that is also independent of any existing network operator or service provider. Instead of connecting each subscriber individually to a central provider, each is linked to several other subscribers nearby by low-power radio transmitters; these in turn are connected to others, forming a network, or mesh, of radio interconnections that at some point links back to the central transmitter.
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