Today, in the data center and information center can be seen everywhere, almost all the main network domination by fiber. As we rejoice in the ascension of the network speed, we have to face all kinds of optical fiber fault that comes with it. This kind of experience is not only in the new network, but also in the process of network transformation and upgrading. Fiber failure sometimes like illnesses entangled with IT personnel, network upgrade to 1G or 10G, but may be just the physical interface, and the actual flow, sometimes impossible to achieve, even the basic connectivity is the existence of hidden dangers, often loss phenomenon.

We think the fiber tester, so in the large network is equipped with optical fiber tester help maintenance has become an inevitable, but the situation is not very ideal, failure to reduce a lot, but there is still a lot of problems cannot be solved, such as the sense of loss, don't use maintenance tools can not solve these problems? How to apply these testing tools in the end it?

1, optical fiber test instrument matters needing attention

Sharp tools make good work。 We can introduce various kinds of optical fibers in the optical fiber network test instrument maintenance, which itself is confirmed by the development of technology, in 10M, 100M optical fiber network link, almost no need to test, you can rest assured use.

With the development of technology, optical fiber loss of the increasingly stringent requirements, the requirements of network 10G optical fiber link loss total control in the 2.6dB, 10M and 100M network and fiber loss requirements will be relatively relaxed a lot, which makes the original network of optical fiber link can be easily implemented almost. But if the rate is increased to 1G and 10G, the original minimum loss will not be able to apply to new applications, the need to test the loss parameters of optical fiber test to determine whether to support the standard requirements. In addition, the high rate of network also requires the optical fiber cable itself, are divided into different categories, in order to improve the rate of fiber support mode need higher bandwidth, especially for multimode fiber is widely used in LAN as shown in Table 1, model of different bandwidth (MBW) link length corresponding to in other words, while the maximum loss of their corresponding is different, and only loss will not be qualified test link can support 10G network, also must have the corresponding bandwidth mode.

In addition to the above mentioned loss, length, mode bandwidth, or the need to pay attention to the dispersion, we have a lot of light switch interface from the LED source to VCSEL light source, is to reduce the dispersion, avoid excessive signal broadening, also used in the test, in order to more realistic performance evaluation of cable, optical fiber for 50 m, the proposed test is also used in the light source of the VCSEL test.

Finally, also need to pay attention to the event of failure analysis, failure is due to some part of the fiber coupler caused, such as bad matching, excessive bending, fault for this kind of event type, need to do a simple test, loss is not good, need to cooperate with the OTDR tester, the localization of the event.

Therefore, if you want to use a good fiber optic test instrument, to really play its effectiveness, in the application of the test instrument is also required to master some of the use of.

Choose the correct test standard, component standard and application standard. If you know the current network applications, such as the measured link is running 1000Base-SX, so the application of standard to test, if you do not know the application, then the standard to test components, such as ISO and TIA in the corresponding standard;

Attention mode bandwidth. In the upgrading of the link, you need to consider whether the current use of the cable to meet the minimum mode bandwidth requirements;

Choose the right light source. When the test is used, the light source is best to use the light emission port which is actually used by the network;

As the test requirements, decided to choose what level of testing, the TSB-140 standard defines two types of testing, OLTS testing is a category, namely the light power meter test, class two is a OTDR test, namely OTDR, single end testing. Class one is suitable for optical loss testing, category two for optical fiber fault location testing.

2, technical application: how to use the tester to solve the optical fiber fault

In the following part of the common problems in optical fiber testing, for example.

(1) case 1, why is the fiber test passed, but the network operation or packet loss?

In the standard choice, many users will make some obvious errors, such as testing is not too much attention to the test fiber is 50 m or 62.5 M.

Two kinds of aperture of the optical fiber to the maximum loss of the value of access is still relatively large, the wrong choice of optical cable test standard will directly lead to the change of decision threshold. For example, if the measured link is 50 m fiber, and the standard test is 62.5 m, and the application is 100Base-FX, assuming that the test results for the 10dB tester, will come to the conclusion that the results of PASS, while the real situation is not qualified, because it exceeded the threshold of 6.3dB. This answers the question in front of the test, but why running data or packet loss.

(2) case 2: by 10 million standard, why still can not support the rate of million?

The existence of such users, network backbone upgrade module and server upgrade they will switch modules, will also test loss of optical fiber network, no matter what appears to be the method, measure down fiber reached gigabit network requirements, loss is less than the standard limit, but the actual effect is not ideal.

Analysis of the reasons, the main is not