Optical module application common problems troubleshooting methods

      According to the optical module in the daily application of the switch on some of the problems, summed up a few points to eliminate the basic method of simple problems, the basic steps are as follows :
      1. you need to check whether the optical module and switch equipment match: most of the switch brands on the market today have their own compatibility requirements, especially when using third-party compatibility optical modules, you need to first determine whether the current optical module is adapted to the switch, you can generally read the port identification information on the switch to determine whether the optical module has been properly identified;
      For example: after inserting the SFP-10GB-SR module into CISCO 4500, you can check whether the module is recognized through switch commands, and if the module cannot be recognized normally, it may lead to the failure of the switch ports to work normally, and the following figure shows that the CISCO 4500 has already recognized the type of the optical module normally (if it cannot be recognized normally and leads to the failure of the communication, it is generally necessary to return to the optical module supplier to solve the problem). The following figure shows that CISCO 4500 has recognized the type of optical module normally (if it fails to recognize the module normally, you need to return to the optical module supplier to solve the problem);

Figure 1 Switch recognizes the module type

      2. if the optical module can be normally recognized on the switch, but the LINK indicator is abnormal, unable to communicate, it is necessary to check whether the link optical path is normal, first of all, we need to check the use of the correct type of optical fiber, single-mode and multi-mode transmission of the optical module, you generally need to use the corresponding type of multi-mode fiber and single-mode fiber in order to normal transmission, the common multi-mode optical fiber is generally orange-red or aqua-green, and the fiber will mark 62.5mm on the outer skin. Shell will be identified on the 62.5/125 or 50/125 words, single-mode fiber is generally yellow, the fiber will be identified on the word G65XX;
      3. check whether the attenuation of the fiber optic link is normal, the final receiving end of the optical power received in the minimum sensitivity settings within the scope of the optical power received by the module if less than the sensitivity value, there may be unstable link, BER, CRC errors and other issues; general manufacturers in the module Datasheet are clearly identified, under the conditions, you can use a handheld optical Under the condition, you can use the handheld optical power meter to test the actual module transmit optical power and received optical power, and find out whether the optical attenuation is abnormal or not; another simple way is to use the DOM function that comes with the module to read out the received optical power report value from the switch, and use it to judge whether the received optical power is at the normal value, as shown in the following figure:

Figure 2 Read out the DOM value of the module from the switch

      4. if the received optical power is less than the nominal sensitivity value, there may be a problem on the optical path, first of all, you need to test whether the fiber optic connection line is connected, whether the end face is polluted, use the fiber optic end face cleaning equipment to clean the fiber optic end face (temporary can also be cleaned with dust-free paper).
      5. if the above detection of optical attenuation is normal, still can not work, you may also need to test the state of the switch port, part of the switch's SFP port is an optoelectronic composite port, you need to configure the state of the optical port; there is also a part of the switch is a multi-rate multiplexed port, such as 25G and 10G multiplexed, the use of 10G modules need to configure the switch port to the 10G rate;
      6. more optical module application issues can be based on our website to provide mailboxes for online consultation.
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