We should often hear the argument that optical module encryption or coding, especially some network equipment of large factories, are required to use their own original modules, otherwise what will happen, then what is coding or encryption? How do third-party module manufacturers respond to device manufacturers' coding and encryption? Can you crack it? What happens if you can't crack it?

If the optical module works in the device, it does not match when working together because there are differences in the standard implementation, not intentionally. But the module that was coded and encrypted didn't work on the device, and that was intentional. According to the definition of the optical module industry standard specification, there are 2 areas in the optical module 128 bytes of each code area, which store the manufacturer, model, serial number, and DDM information (allowed voltage, current, temperature, receiving and luminescence power range and the actual collection of these values) and compatibility code.

Through the 2-wire serial interface (SCL, SDA), the transceiver provides serial ID memory contents and diagnostic information about the current operating conditions, memory mapping specific data fields.

Many equipment manufacturers, in the switch and other network equipment, do the limit, after the optical module is inserted, it will read the information of the code area inside the optical module through the IIC bus of the switch, through this information, the device can determine whether the module is its own original module, if it finds that it is not the original, you can take some actions. Different manufacturers here will have different practices, there are mainly such a few categories.

1. Do not do any compatibility control, that is, the device does not read the compatibility code inside the module to make a judgment, any module can be plugged in, basically all white brand switch manufacturers will do so, such as Shengke Network, some brand manufacturers will do so, and some low-end products of large manufacturers do not write code control.

2. Check the compatibility code in the module to determine whether it is compatible. However, since the compatibility code is in plain text, any third-party module manufacturer can easily obtain this compatibility code, so that when these third-party module manufacturers leave the factory, they can be compatible as long as they write the compatibility code of the compatible manufacturer in their own module. So this approach is equivalent to not fortifying. Many network card manufacturers part or all of their products, are this practice.

3. The compatibility code in the module is a dynamic compatibility code, which is calculated according to some information in the module, such as serial numbers, or even some unique ids in the chip, and then written in through a specific algorithm. In this case, it is relatively difficult for a third party to crack, but as long as it can know the algorithm and all the fields and storage locations of the participating algorithms, That's OK, too. Some of the products of some large factories are in this way. For the vendors who want to check compatibility in 2 and 3 above, once they find that they are not compatible, they will have some different measures, some will directly not UP (which is equivalent to saying that you do not use my original module, I will not let you work), some will alarm and/or let you see the DDM information (which is equivalent to saying that you do not use my original module, I let you use it). Current manufacturers generally use the latter, which is a more moderate approach. This is not a technical problem, but a marketing problem.

C-light has 10+ years of experience in the manufacture of third-party optical modules, and actively conducts compatibility tests for switches, servers and boards of various brands on the market, and completes compatibility verification by means of client testing and in-factory analysis of equipment purchase.

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The coding area inside the optical module is an industry standard (different types of optical module standards are different), and the direct interface between the device (switch, router, network card, etc.) and the optical module is also standard (IIC standard), so in theory, it is very easy to make a coder out, and the coder is a necessary product for the module manufacturer. In fact, what many people don't know is that the switch manufacturer can also use the switch as a coder, and can do batch coding, because the switch is also a standard IIC interface between the optical module, it just depends on whether the switch manufacturer is willing to do it, the switch of Shengke Network opens up this capability. In theory, the code writer can write the optical module of manufacturer A into the code of manufacturer B, module manufacturers in order to prevent others from writing their own modules, have set password protection, you do not know the password, after writing, once the device restarts or the module is reinserted, the code written is lost.