Cisco Networking Academy Program CCNA 1 and 2 Companion Guide, Revised part 57 is the Cisco approved textbook to use alongside version of the Cisco Networking Academy Program CCNA 1 and CCNA 2 web-based courses. The topics covered provide you with the necessary knowledge to begin your preparation for the CCNA certification exam (640-801, or 640-821 and 640-811) and to enter the field of network administration. | Page 529 Tuesday May 27 2003 8 57 AM WAN Routers 529 More Information Resource Utilization Rates Continued These rates can be tricky to analyze and might even be misleading. It is not uncommon for example for network-management software packages to capture utilization data in time intervals. These intervals can be 1 hour 5 minutes or just about any other interval. If set too coarsely the sampling frequency can miss short-duration fluctuations in bandwidth consumption. If the sampling is too frequent you can find yourself mired in a meaningless morass of data points. The trick is finding the right frequency that provides meaningful data about how the network is performing relative to the users expectations. Beyond merely selecting the sampling rate is the issue of sampling window. The sampling window should be determined by the users requirements for WAN availability. If the utilization samples are spread over a 24-hour day and a 7-day week whereas the users work only 10 hours per day 5 days per week the statistical data is not indicative of how well the users requirements are being met. Utilization rates are a wonderful statistical tool for monitoring and measuring the status of transmission facilities. However they are not the only metric for assessing a network s performance. The network is successful only if it satisfies the users requirements. Therefore a combination of performance metrics that provides a multifaceted composite perspective is likely to provide a better assessment of the network s success than any single metric can offer. WAN Routers Just as computers need operating systems to run software applications routers need Cisco IOS Software to run configuration files. These configuration files contain the instructions and parameters that control the flow of traffic in and out of the routers. Specifically by using routing protocols to direct routed protocols and routing tables routers make decisions regarding the best path for packets. The .
