What are the working modes of POE? What is the PoE power supply mode?

There are 3 working modes of PoE.

1. Standard switch mode. When the switch is switched to standard switching mode, it becomes an ordinary unmanaged switch, and all ports can communicate with each other, and the PoE port can supply power normally. It is suitable for common data transmission environments.

2. **Monitoring mode. **The monitoring mode is designed for monitoring applications, when the switch is connected to multiple network cameras, it is recommended to enable this mode, and connect the uplink ports to the uplink devices, which can effectively reduce the jamming and mosaic in the monitoring network. In this mode, the PoE ports of the switch cannot communicate with each other.

For switches with only one row of ports, the PoE ports can communicate with the uplink ports separately. For a switch with two rows of ports, the POE port on the front end can only communicate with the uplink port with a small port number. The PoE port on the backend can communicate only with the uplink port with a large port number. The two uplink ports cannot communicate with each other.

3. VLAN isolation mode. When this mode is changed, each PoE port cannot communicate with each other, but can only communicate with the uplink port. If there are multiple uplink ports, the uplink ports can communicate with each other.

It is suitable for scenarios where wireless APs are connected, which can effectively suppress network storms and improve wireless network performance.

Note: Multiple uplink ports cannot be connected to the same switch or the same server, and the mode switch will take effect immediately after the switch is switched.

Unmanaged PoE switches, generally plug and play, no configuration required, unmanaged PoE switches with mode transfer switches also support standard switching, monitoring, VLAN isolation three working modes.

In monitoring and VLAN isolation, the concept of uplink ports is introduced, which refers to ports connected to aggregation or core networks, which usually have higher interface rates and do not support PoE functions.

The port marked with the word "uplink" is the uplink port, which is generally on the far right of the switch, with 1 to 2 ports (some are 4 ports for photoelectric multiplexing, but in fact, only 2 ports can be used at the same time, such as Tianbo's TBC-PS5424FE-2GFE).

There are two modes of PoE power supply: mode A (idle line 45, 78 power supply): 45 is +, 78 is -; Mode B (data line 12, 36 power supply): 36 is +, 12 is -.

The standard definition of the supply voltage is DC 44-57V.

The standard definition of the supply voltage is DC 50-57V.

PoE technology can ensure the normal operation of the existing network while ensuring the safety of the existing structured cabling, and minimize the cost. The IEEE standard is based on Ethernet.

The new standard for PoE in power delivery systems, which adds a related standard for direct power supply over a network cable on the basis of IEEE, is an extension of the existing Ethernet standard, and is also the first international standard on power distribution.

Extended information: PoE system composition: A complete PoE system includes two parts: Power Sourcing Equipment (PSE) and Powered Device (PD).

The PSE device is the device that powers the Ethernet client device and is also the manager of the entire PoE Power-over-Ethernet process.

The PD device, on the other hand, is the PSE load that receives the power supply, that is, the client device of the POE system, such as IP**.

Security cameras, APs and PDAs.

PDA) or mobile** chargers and many other Ethernet devices (in fact, any device with a power of up to 13W can draw the corresponding power from an RJ45 socket).

Based on the IEEE standard, the two establish information about the connection status, device type, power consumption level and other aspects of the PD of the power receiver device, and use this as the basis for PSE to supply power to the PD through Ethernet.

The motherboard now supports three hard drive modes: Normal, LBA, and Large modes.

Normal mode is the earliest IDE method. In this mode, the BIOS and IDE controllers do not convert the parameters when accessing the hard disk. The maximum number of cylinders supported by this mode is 1024, the maximum number of heads is 16, the maximum number of sectors is 63, and the number of bytes per sector is 512.

Therefore, the maximum supported hard disk capacity is: 512 63 16 1024 = 528MB. In this mode, even though the actual physical capacity of the hard drive is larger, the accessible hard drive space can only be 528MB.

lba(logical

blockaddressing) logical block addressing mode. The hard disk space managed by this mode breaks through the bottleneck of 528KB and can be reached. In LBA mode, the parameters such as cylindrical surface, head, and sector are not the physical parameters of the actual hard disk.

When accessing a hard disk, the IDE controller converts the logical address determined by parameters such as cylinders, heads, and sectors into the physical address of the actual hard disk. In LBA mode, the maximum number of heads that can be set is 255, and the rest of the parameters are the same as in normal mode. From this, it can be calculated that the accessible hard disk capacity is:

Large hard disk mode. This mode can be used when the cylinder of the hard disk exceeds 1024 and is not supported by the LBA. The large mode takes the method of dividing the number of cylinders by 2 and multiplying the number of magnetic stool heads by 2, resulting in the same total capacity.

For example, in normal mode, the number of cylinders is 1220 and the number of heads is 16, and in large mode, the number of cylinders is 610 and the number of heads is 32. In this way, in the DOS opinion, the number of cylinders is less than 1024, and it will work normally. At present, basically only the LBA is of practical significance.

When a PSE power supply device is deployed in a network, the PoE power over Ethernet working process is shown as follows.

1.Detect.

At first, the PSE device outputs a small voltage at the port until it detects that the cable termination is connected to a powered device that supports IEEE standards. Absence of a profiled limb.

2.Classification of PD-end devices.

When a PD is detected on the receiver device, the PSE device may classify the PD device and evaluate the power loss required by the PD device.

3.Power is on.

During a configurable start-up period (typically less than 15 seconds), the PSE device starts supplying power to the PD device from a low voltage until a 48V DC power supply is provided.

4.Power supply.

Provide stable and reliable 48V DC power for PD equipment to meet the power consumption of PD equipment without exceeding.

5.Power.

If the PD device is disconnected from the network, the PSE will quickly (usually within 300 400ms) stop powering the PD device and repeat the detection process to check whether the termination of the cable is connected to the PD device.