By looking at examples of troubleshooting, we can understand the methods we’re outlining in this document. Consequently, we will consider two case studies.
Case Study 1: Obtaining Switch Statistics
Sometimes obtaining the information you need can involve moving from one building or site to another. Travel time is lost time. So, in this illustration we see how OptiView can be used to learn about a link to a server and the configuration of the network at that point.
Let’s say we have a server that is connected to a switch in some part of the network and users are complaining that the server is responding slowly. Using the unique layer 2 and layer 3 trace route techniques described before, we find the path to the server and the layer 2 switch to which the server is connected. By highlighting that switch and clicking on Device Detail and the Interfaces tab, we can get the screen shown in Figure 49.
图 49. The Switch Interface Screen
From this screen, we can determine which port is connected to the server, in this case port 9. Then by clicking on the bar graph button next to View, we can query the switch to get the statistics on that link to the server. This is shown in Figure 50.
图 50. Link Statistics
This allows us to see the utilization and error levels on the link and even access an RMON history study of the link, if it is enabled on the switch. Sometimes servers are browsing on a link. If that is the case, there will be an abnormally high level of broadcast traffic. Or, you might find that there are errors caused by a physical link problem such as a defective NIC or bad copper cable. Being able to see the link without being physically at the switch provides a considerable savings in time.