【Problem Description】

Some cameras connected to huawei switch can be powered on successfully and some cameras connected to huawei switch cannot be powered on.

【Problem Analysis】

                          Step 1     Huawei R&D and GTAC engineers conducted several tests and found that the problem.

On the Switch (TAISM-138A-CCTV-SW), GigabitEthernet0/0/1 and GigabitEthernet0/0/2 cannot be powered on, GigabitEthernet0/0/11 can be powered on successfully.

                          Step 1     Through port cross-validation, it is found that the 11-port camera can be powered on when it is changed to port 0/0/1. the 1-port camera still cannot be powered on when it is changed to port 0/0/11

With this verification we confirm that there is a difference between the cameras

                          Step 2     The register is 0x73 when the camera is not powered on.0x73 means: classification overcurrent, the impedance detection result is too small

                          Step 4    The process of powering on the phone by the PoE Switch includes: idle -> detection - > Classification - > power on, as shown in the following figure.

PoE power supply process

In summary, the reason why the 1-port camera cannot be powered on is the abnormality when the camera shakes hands with the switch.

                          Step 5   There are two possibilities for this situation: individual abnormality of camera and Switch detection signal is interfered.

                          Step 6     Typically, PoE switches use pairs 1/2 and 3/6 to power the camera, and pairs 4/5 and 7/8 are reserved, and we check that the camera（that can powered on）port rate is FE. So we did one more test：we use one FE cable(that only have pairs 1/2 and 3/6)to connect the camera to the switch, and it can be powered on successfully

【Root Cause】

In summary, we analyzed that the reason of cameras (in TAISM-138A-CCTV-SW) cannot be powered on is that the switch detection signal is affected by the pairs 4/5 and 7/8 signal.

【Solution Description】

A、Connect camera and switch with a FE network cable(The camera is a FE device)

B、The network cables on the switch side are re-crimped to FE.

C、To add the special jump cable and RJ45 connector between current cables and the camera, The special jump cable will only contain 1-2 and 3-6 pairs.

Note: The special jump cable can only be used for 100M Ethernet connection.