Practical Industrial Data Networks:Design, Installation and ...

242 Practical Industrial Data Networks: Design, Installation and TroubleshootingFigure 15.9OMNIscanner2 cable tester15.6.3.3 Fiber optic cable testersFiber optic testers are simpler than UDP testers, since they basically only have to measurecontinuity and attenuation loss. Some UDP testers can be turned into fiber optic testersby purchasing an attachment that fits onto the existing tester. For more complex problemssuch as finding the location of a damaged section on a fiber optic cable, an alternative isto use a proper optical time domain reflectometer (OTDR) but these are expensiveinstruments and it is often cheaper to employ the services of a professional wire installer(with his own OTDR) if this is required.15.6.3.4 Traffic generatorsA traffic generator is a device that can generate a pre-programmed data pattern on thenetwork. Although they are not used for fault finding strictly speaking, they can be usedto predict network behavior due to increased traffic, for example, when planning networkchanges or upgrades. Traffic generators can be stand-alone devices or they can beintegrated into hardware LAN analyzers such as the Hewlett Packard 3217.15.6.3.5 RMON probesAn RMON (Remote MONitoring) probe is a device that can examine a network at agiven point and keep track of captured information at a detailed level. The advantage of aRMON probe is that it can monitor a network at a remote location. The data captured bythe RMON probe can then be uploaded and remotely displayed by the appropriate RMONmanagement software. RMON probes and the associated management software areavailable from several vendors such as 3COM, Bay Networks and NetScout. It is alsopossible to create an RMON probe by running commercially available RMON softwareon a normal PC, although the data collection capability will not be as good as that of adedicated RMON probe.15.6.3.6 Handheld frame analyzersHandheld frame analyzers are manufactured by several vendors such as Fluke, Scope,Finisar and PsiberNet, for up to gigabit Ethernet speeds. These little devices can performlink testing, traffic statistics gathering etc and can even break down frames by protocoltype. The drawback of these testers is the small display and the lack of memory, whichresults in a lack of historical or logging functions on these devices.