Cost Efficiency of Mesh Optical Network System - Research Paper Example

?Cost efficiency of Opaque Network System, Transparent Network System and Translucent network system of Mesh Optical Network System inserts name] Course: [student inserts course] Tutor: [student inserts tutor name] Date: 09. 12. 2011 Cost efficiency of Opaque Network System, Transparent Network System and Translucent network system of Mesh Optical Network System Introduction With strategic evolution in telecommunication networks and ever increasing multimedia demand by telecom consumers, optical mesh network is solution to any service provider. Mesh optical network achieves transmission of information over optical media in a systematic manner. The optical transport network consists of the networking capabilities and the technologies required supporting bulky multimedia data for long distance. Optical transport networks provide high speed data communication, high bandwidth and excellent termination. However, service providers require low cost network to optimize profit. This paper analyzes installation cost of opaque networking system, transparent networking and translucent networking systems as types of optical mesh networks. To examine Optical mesh network types and analyze their installation cost effective factor one needs to base observation on the following basic network service providers concern for a core optical mesh. Cheap network elements that will not cost the operator a lot in procuring and installing or that needs less re-engineering. Non-proprietary constrained network utilities, option of buying from different vendors Scalability with low footing expense Service assurance with capacity and redundancy Fault detection and management beyond installation Transparent network This Optical network sends signal from source to destination in form of light path. The optical information is passed through optical switch and routers from the initial generator to final destination. The wavelength doesn’t undergo optic-electric conversion (O/E), client network element like a router will interface by use of long haul optics to communicate with the wavelength division multiplexer, making it to remain in the same wavelength. Meaning the information remains in optical domain (OOO) and there is no optical-electronic-optical (OEO) conversion, only a small switching fabric is needed to interconnect the wavelength division multiplexers and client element nodes. Remaining in optical domain creates a simple node architecture at its intermediate switch nodes since no electronic switching fabrics is needed to access wave division multiplexers (WDM), this saves cost and space. It employs nodes like directionless / colorless Reconfigurable Optical Add Drop Multiplexers (ROADM) or Optical Cross Connects (OXC). It is also easy to carry out an upgrade of such a network because of insensitivity of data rate change and protocol of light channel. Transparent network can also employ another cost effective architecture switch that may include a single large fabric instead of multiple switch matrices of small port counts but this also contributes negatively on lack of flexibility. However it has draw backs. According to Boullet and Ellinas, “if one is to provide flexibility, such an architecture design would require the use of tunable lasers at the clients and wavelength conversion. Since signal from client remain on the same wavelength when there is no wavelength conversion only a small size switch fabric is needed to interconnect the WDMs and NEs in a node, which translates to switch scalability” (Boullet & Ellinas, p. 5). Inflexibility leads to increased band width and network operational cost. This negates the saving advantage. Transparent networks needs a centralized planning of each link, this is because of disjoint links since no conversion of the wavelength occurs creating a network of n, where n is the number of WDM channels. This builds a network for unrestricted routing and redundancy capacity sharing involving only optical but would lead to increased bandwidth and network cost. On regeneration in o-e-o the benefit is reset but in transparent it doesn’t occur since its optical only (o-o-o) leading to accumulation of optical transmission impairments at each node. Physical impairments such as chromatic dispersion, polarization-dependent degradation, WDM filter pass band narrowing, component crosstalk, amplifier noise and others. These impairments are critical in any network and can cause network failure. This calls for each optical part to be individually transmission engineered to contain impairment and loss. This can be costly during installation and if left without being contained it can cost an operator a lot. Operators don’t have flexibility to choose their vendors since the design of Density WDM (DWDM) is proprietary. Since the network elements are all optical (OOO) without O/E conversion making it impossible to develop standard for interface of high capacity WDM, network operators thus have no choice of selection. Transparent network elements are mostly single vendor including the client elements. According to Labourdette and Zhang, “The interface from the client NE connects through the all-optical switch to the WDM system without O/E conversion, and it is not possible to develop a standard for interface of high-capacity WDM.” (Labourdette & Zhang, p. 4) Performance monitoring and fault detection are complicated since there is no wavelength being reset. This is because a there are no signal associated overhead channels to support numerous operation. Performance is hindered because transparent network doesn’t provide information about the data traffic; this makes it unintelligent and difficult to monitor performance. Lack of wavelength conversion also leaves only client based dedicated backup path protection (DBPP) as easiest option for service providers to provide. This is because the wavelength continuity constraint on backup paths makes resource sharing very difficult in transparent network. These results no shared backup path protection (SBPP) easily offered. This means that the capacity requirement for protected services is significantly higher than that of opaque networks. Transparent network has cross layer problem when coupling the physical and logical layer. Its therefore clear that a number of key factors for carrier operators like wavelength conversion , multi-vendor interoperability of transport equipment, a dynamic configuration, signal impairment ability and inflexibility makes low network-level cost very hard to meet in a transparent network architecture. Transparent network architecture may be viable option for a small scale networks with pre-determined routes and limited number of nodes otherwise not best option. Opaque Optical network where electrical generation are abundant, it employs electrical switch or routers to convert signal from optical to electronic (OEO). OEO interfaces commonly carry out both regenerations: re-amplification, reshaping and retiming (3R). The involvement of electric between the source and destination enhances traffic monitoring and fault detection all of which are done electronically. Opaque networks utilize transponders in the WDM systems. It uses opaque switches with an electronic switch fabric to achieve OEO. Opaque switch fabric has transceivers which enables access to SONET/SDH overhead bytes for control and management functions. The transceivers are the ones that provide fault detection and isolation a very key quality aspect. The transceiver as well performs monitoring and connection verification. During installation the transceivers support implementation of network routing and restoration protocols. Opaque switch also comes with key functions like grooming and multiplexing that help verification , control and management, this will attract network operators to install opaque network against transparent. Opaque network employ span engineering to eliminate engineering end-to-end systems. This allows full flexibility in signal routing that overcomes the challenge experienced in transparent network. There is significant cost saving since sharing redundant capacity is possible with OEO. Network capacity is utilized for service without any restriction a good factor that each operator will take advantage to install. Opaque networks size and light path length can be large since regeneration and retiming are present along the physical path of the signal. The regeneration may reduce the number of network elements, bring the cost down. Service providers and operators can employ a standard interface within the opaque network because it offers interoperability, one can select from different vendors this gives a cost comparison opportunity. Operator can do a selection of a cost effective vendor as key player to any operator aiming at making profit. It also permits link-to-link incorporation of new technology since the network is partition into point-to-point optical links. So any service provider looking at evolution of the link can do a link-to-link network evolution. Opaque switch architecture uses Phothonic Integrated Circuits (PICs). This approach allows low-cost opaque architecture by allowing low-cost OEO conversion according to Boillet and Ellinas, (Boillet & Ellinas, p. 8). The cheap opaque switch design is meant to provide a low-cost network element that network operators can go for. Opaque networks provide necessary control and management function a tool to most network operators during installation. Even though network management is simplified the huge number of OEO devices at each node may greatly increase total network cost. Opaque network may uses large electronic switching cores as each node needs to carry out signal conversion for OEO this is more expensive duly power consumption. The use of transponders which are not transparent to the data rate of optical channel makes the opaque networks not good at up gradation. It also requires technically re-deploying new electronic switch nodes and higher rate transponders when the network is upgraded to a higher rate network. It’s purely independent of the logical and physical layer in networking. Opaque networks look more promising to network operators, as discussed above the opaque network may look viable in cost terms if operator has large scale network with long physical path. The greatest difference in cost effective can is observable depending on how big network is and link planning. If planning involves high use of OEO elements then it can increase impact on the overall cost of installation. Translucent networks This is a hybrid of the opaque and transparent network. As analyzed each has its pros and cons, translucent networks merges the best features of transparent and opaque network to create a hybrid network that will provide operators quality feature while mitigating their disadvantages. It allows the connection to stay transparent for as long as signal quality will withstand before degrading, it then undergoes regeneration process to recover original signal. Sparse generation can be achieved by placing translucent nodes at strategic position this minimizes blocking in the network. Translucent planning is set to aim at employing the smallest number of regeneration resources as possible and the eventuality is to reduce installation cost. According to Chatelaine and Mannor, “sparse placement of OEO nodes usually requires less regeneration nodes and is more cost effective than the domains or islands of transparence approach.” (Chatelaine & Mannor, p. 1) It uses set of strategically place regenerators by seeking a graceful balance between network design and service provision. The regenerators at each OXC are available to all wavelengths incidents to the nodes and their use well optimized. Sharing of the generators has a high impact on the number of generators used, the less the numbers used the less the cost of installation. Generators as well alleviate collision when routing light paths and improves wavelength resource utilization, for a network operator. Resource utilization is done by the very translucent regenerators. Translucent optical networks are broken into two and each has its effect on installation. The first category has sparsely distributed opaque switch nodes this means only few switch nodes are electronic and all the others are all-optical. Minimizing the number of opaque switch and as result brings down the cost in this category. The second category of translucent utilizes translucent switch nodes, in which each node is made up of two switch cores including electronic and optical switches. This optical channel bypasses an intermediate switch node goes through optical switch core and only when the quality of channel becomes poor requiring to go through regenerators. It contributes to the number of optical switch and reduces the power consumption. According to Shen and Tucker, there are challenges that need to be addressed when operating, organizing and planning translucent networks. These include transparent island division, Opaque node placement, 2R/3R regenerator allocation, and Routing and wavelength assignment. Transparent island division, Opaque node placement, 2R/3R regenerator allocation affect planning of translucent network. In addition the forth challenge (routing and wavelength assignment) affects the operations of translucent networks (Shen & Tucker, p. 3) The implementation makes translucent networks the best to service providers because of increased revenue-regenerating capabilities through fast turn up and rapid provisioning. Translucent as well has a wavelength-on-demand service that increases capacity and flexibility. Service providers also enjoy increased return on capital from cost effective and survivable architecture that help protect future uncertainties. Reduced operation cost through more accurate inventory and network topology information. The network is also scalable, resource optimization and automated process that eliminates manual steps. Control and management of this network is more flexible than that of opaque or transparent. According to Ou and Murkherjee, “cost could be reduced in a translucent network where the regeneration functionality is only employed at some nodes instead of at all nodes.” (Ou & Murkherjee, p. 724) This means network operators will be advantaged by using the translucent network. Conclusion Today optical networks are much more cost effective than metallic cable, satellite and radio long haul. However, within optical network types the cost of installation can vary depending on the architecture. The three types of optical networks discussed above have their pros and cons. Transparent networks employ only optical network elements that can save much space and cost because the is no O/E conversion but may use many OOO elements. Furthermore the optical domain elements are constrained to vendors making operators to lack flexibility in selecting network elements which can lead to buying expensive proprietary that will affect cost of installation. Other drawbacks including lack of performance monitoring, signal impairment, difficulties to detect faults makes it unfriendly; hence, no low cost effectiveness. This therefore means that operators cannot enjoy its cost effectiveness. Installing opaque networks also requires the use OEO elements. The number of OEO elements to be used in each link or physical path highly affect the cost of installation, it also consume more power increasing the cost of operation. Network operators overseeing future upgrading data rates may face challenges as opaque is very resistant and can cost a lot. The number of regenerators has a high impact in the network installation. But the accompanying advantages make is a better network if compared against transparent networks, it offers quite advantages like fault detection, traffic monitoring, capacity sharing which transparent network doesn’t provide. Translucent being the hybrid of the two and taking advantageous side of them, stands out clear as the most low cost optical network. Network operators seeking to mitigate cost will basically select translucent to tap its advantages while minimizing the cost of installation. The low-cost-level is highly influenced by the optimal utilization of optical switch and sparse placement that minimize blocking. Translucent network gains another mileage in cost cutting as electric switch are used only if the signal has degraded, the use of the regenerators only when required sees the less use of OEO, Reducing the number of OEO cuts down on installation cost electric consumption costs. Translucent as well offers interoperability by use of standard interface. Network operators free from proprietary vendors, they can compare prices and procure the once that are of low cost and reduce the installation cost. Other advantages like flexibility and capacity sharing. Network operators therefore can select the cheapest among the vendors this reduces cost. With the strategic placement of OEO nodes amidst lower cost OOO nodes the possibility of highly minimizing overall network cost while also using more localized protection and restoration schemes with mesh efficiency is yet another reason to conclude that Translucent indeed is the low cost optical network. Therefore with translucent combining the strength of the two networks (Opaque and Transparent) and harnessing there powerful cost effective features and creating a network that reduces installation cost and still covers long physical path, one could easily conclude that translucent is cost effective in terms of installation. Works Cited Gangxiang Shen & Rodney S. Tucker. Translucent Optical Networks: The Way Forward University of Melbourne, 2007 Eric Bouillet & Georgios Ellinas. Path routing in mesh optical networks, Edition 2 Cambridge University press, 2007 Benoit Chatelain, Shie Mannon, Francios Gagon & David V. Plant. Non-Co-operative Design of Translucent Networks Guiseppe Rizzelli, Guido Maier, Romolo Longo . Comparison Of Opaque And Translucent WDM Networks with Different Regenerator-Placement Strategies under Static and Dynamic Traffic J.F. Labourdette & Zhengsheng Zhang. Opaque and Translucent Networking Optical network magazine, May/June 2003 Canhui Ou & Biswanath Mukherjee. Survivable optical WDM networks Business media, 2007 Read More