Many telecommunication carriers offer leased circuit as a solution for this distance barrier. Determining the link bandwidth and topology of the network should be an important subject to discuss. To minimize operational fee by expanding a remote office is our main goal. Yet, we will unable to achieve this objective if we miscalculate the network development cost, although, we eventually have the ability to deliver data communication among the nodes (we often call a network entity as a 'node').

WlvNET is software that enables us to calculate network development cost for each topology that we simulate. By knowing the cost, we will able to find out the best network path that meet the maximum cost requirement for the company.

What wlvNET do is basically an iteration of an algorithm to find the shortest-path of a link related to the incoming/outgoing traffic of a node. It uses Djikstra's algorithm as this method has been used in most of shortest-path calculation (lecture notes, sli. 13). Any topology possibilities could be shown by this software. Unfortunately, we have to decide the optimum network topology manually. This would be a very essential issue.

One of the parameter that this tool uses in its iteration is incoming/outgoing traffic. This parameter need deep discussion as it will effect the link needed to overcome the traffic. One thing should be taken care of is that upload and download traffic have a ratio which depend on the application used by the end-point/user. For example, simple usage of internet to browsing, e-mail, and instant-messenging would give an upload/download traffic ratio 1:8. Other type of usage, such as LAN-emulation and banking application using frame-relay connectivity will yield a ratio of 1:3. Moreover, a voice application, such as voice over IP has a ratio of 1:1 for its upload/download traffic. These measures based on the traffic pattern tendency that my company record from the customer's private link.

The second variable that important for this software to run appropriately is, of course, the distance between any nodes. Our main goal is to find the minimum cost for sum of the entire link. Hence, cost per kilometer for a link is a very crucial issue.

Distance between the nodes could be achieved by using simple coordinate calculation. I use a plain method where I map the cities of Vin da France network to (X, Y) coordinates and subsequently, scaling of the distance will depend to wlvNET calculation mechanism. I have tried several experiments and I come to a conclusion that wlvNET will automatically scaling the distance based on the coordinates as the input. Hence, the cost of the network will remain the same although we increase the distance value for a link. The cost will be different if we make a correction on the coordinate position.

Another optional variable is the personnel population of each node. This variable will result to final traffic calculation that going from/to each node. Actually, we need to determine the distribution traffic pattern for each personnel's traffic. However, due to limitation of each user's statistical data, I take an assumption that each personnel will have an equal daily traffic.

One weakness of this application is that we could not simulate multiple line type to be used in the network. We only able to specify one line type for each single simulation, whereas combination of line types will result a
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