computer science assignment

CS625 Business Data Communication and Networks Prof. L. Chitkushev Assignment 4  Lecture 8 
1. (10 pts) What are the three technology layers in backbone design? List the preferred technologies used in each of these layers.
 2. (10 pts) How can you improve the performance of a backbone network (BN)? 
3. (10 pts) Define a routed backbone, a switched backbone, and a VLAN.  What is the best practice backbone design of today and why?  Lecture 9 
4. (10 pts) Is a WAN that uses dialed circuits easier or harder to design than one that uses dedicated circuits? Explain. 
5. (10 pts) How do packet switched services differ from other WAN services?  CareGroup Healthcare System Scenario Below are the details of a scenario which is the basis for answering questions 6 through 10. First read Management Focus 9.1 “CareGroup’s Dedicated Circuit Network” and look at figure 9.8 on page 306 in the textbook. Next read the additional information provided below. Lastly, use this information as a basis for answering the remaining questions in this assignment.  CareGroup Healthcare System is planning an expansion in their network, and has hired you to be their network architect for the project.  It is up to you to recommend an upgrade architecture to CareGroup that will satisfy their needs for the next five years.  Here is the current situation:  The SONET ring is maxed out at the OC-1 / STS-1 rate. You need to consider upgrading this ring.   CareGroup needs to add five (5) more medical centers around the Boston area.  These additional medical centers have the same capacity needs as all the others.   All the existing T3 links are saturated and need to be upgraded.  This includes the T3 links from the Data Center to the medical centers and to the Internet.  You do not have to account for the links to the Physician offices shown below the Internet in figure 9.8.   CareGroup anticipates that in five years all spans will have to have 6 times their current capacity (i.e. if the span is a 100Mbps link, it would need to be a 600 Mbps link in five years).     You have found a pricing sheet containing the following information:  OC-1        $1,200/mos OC-3        $3,700/mos OC-12        $5,000/mos T-3 Link    $1,400/mos T-4 Link    $1,500/mos   6. (10 pts) Calculate the monthly cost of CareGroup’s existing network.  Show all your work.  Note:  Actual pricing would be based on distance, data rates, number of terminations, etc.  However, in this exercise these can all be considered as static costs and do not have to be accounted for.   You only need to account for the number of buildings and links / spans to interconnect them.  7. (10 pts) Define the best upgrade solution for CareGroup’s network based on monthly costs, given the situation described in the bullets above.  Use the capacity charts on pages 304-305 in your text to determine your solution.  Explain your upgrade in detail.    Note that T carrier circuits transmit data through the telephone hierarchy, whereas optical carriers run on fiber optic cable.  This means that a T-1 link can be upgraded to a T-3 link, for example, without any change to the layer-1 media, just as an OC-3 can be upgraded to an OC-12 without any change to the layer-1 media, since fiber optic cable would have already been installed.  For the purposes of this exercise, however, no layer-1 media installation costs need to be considered.  8. (10 pts) Provide the monthly cost of CareGroup’s network with your upgrade in place.  Show all your work.  9. (10 pts) Draw a diagram of CareGroup’s network with your upgrade in place.  10. (10 pts) An important skill in business communications is determining pricing.  Search online for the actual price structure for OC-1, OC-3, OC-12, T-3 Link, and T-4 Link, from a local carrier your area, and provide this information with the corresponding URLs where you found the data.  If you cannot obtain local carrier pricing, provide the prices listed at US Access for generic prices:  http://www.usaccess-llc.com/ 11. One of the major concerns in backbone networks is fault tolerance and disaster recovery. Backbone networks tend to cover the greatest distances; hence redundant paths are the most expensive. Also, the possible physical paths for lines to be laid is limited by a few kinds of rights-of-way: highways, streets, railroads, power lines, pipelines, etc. How would you address this problem for your network? This discussion is graded. Your posts are not editable.  12. Although circuit switches have low congestion and high utilization rates, there may be times when a connection can’t be established. Routers can only achieve 35- 40% utilization before they begin to experience congestion, but they never refuse service. Routing is supposed to be cheaper but there is far more computing power in a core router than any circuit switch. Is packet switching really better than circuit switching or are the circuit switched vendors just building the wrong equipment?