23 Feb SFP+ module not holding in port

There are two types of optical transceiver problems – software based and hardware based. This time definitely we talk about hardware based problem. SFP module is not locking in port. This means when engineer plugs it into switch port the SFP module is not producing fixating noise (click), and does not fixate itself in port. As a result the module can be easily pulled out. This is dangerous because it allows to someone by mistake trip on cable, or pull by the optical fibre and SFP module pops out. Practically this problem is observed mostly with few 10G-SFP modules plugging into CISCO ASR, Huawei or EXTREME switches, but in general can happen to any vendor equipment.

After diagnosing SFP module hardware and comparing with module which locks in port successfully, we can see that there are some hardware differences which obviously cause this problem. The locking mechanism consists of fixating peg, sliding plate and handle. In normal process when SFP module is slided into switch port, the port has locking leg which fixates SFP module by the peg. Puling handle the sliding plate on SFP module moves and with two handed 45 degree pins slides under the switch’s locking leg, raises it and releases SFP module from port. Problematic SFP`s has thicker sliding plate end which supports the handle. As a result 45 degree pins on the other side of SFP sliding plate is too close to the locking peg and when SFP is inserted into switch port, switch’s locking leg can’t fit between 45 degree pins and SFP locking peg. The module is not fixated into port.