If your Cisco switch PoE is not working, the most common causes are an exhausted PoE power budget, a disabled inline power configuration, physical cable faults, incompatible powered devices (PD), or a crashed PoE controller. When a problem occurs with PoE, in most cases, the error symptom can be simply shown as the PoE switch not providing power, and the powered devices will stop. This guide is for troubleshooting Power over Ethernet (PoE) in the Catalyst 3750-E, 3750, 3560-E, and 3560 switch product families. Topics related to earlier PoE switches are also included. However, when PoE fails, it can disable critical infrastructure like IP phones, wireless access points, and security cameras. PoE is a networking feature defined by the IEEE 802.
[pdf] Huawei S5700-48TP-PWR-SI supports 20 PoE+ 10/100/1000BASE-T ports and 4 combo ports (10/100/1000BASE-T (PoE+) + 100/1000BASE-X). It has no Power supply, needs to purchase additional power W0PSA5000. Figure 1 shows the appearance of Huawei S5700-24TP-PWR-SI switch. Table 1. Huawei S5700 series Ethernet switches are next-generation energy-saving GE switches designed to provide high-bandwidth access and Ethernet multi-service aggregation. Based on cutting-edge hardware and Huawei Versatile Routing Platform (VRP) software, the S5700 provides a large switching capacity. The product adopts a new generation of high – performance hardware and software platform,provides flexible and cost – effective full-gigabit access and uplink portsHuawei S5700-28P-PWR-LI-AC is Layer 2 Ethernet Stackable Switch, supporting 24 x PoE+ 10/100/1000BASE-T ports and 4 x GE SFP Ports.
[pdf] A managed PoE switch combines two crucial elements in network management: Power over Ethernet (PoE) and full network control. Unlike unmanaged switches that are easy to use and just need to be plugged in, managed switches give you more control. In this blog, we will guide you through the key steps to ensure a successful PoE. Lantronix's multi-port managed and unmanaged PoE switch family is designed to withstand enterprise or hardened applications.
[pdf] To display information about the inline power for all interfaces or for a specific interface, use the show power inline Privileged EXEC mode command. interface-id—Specifies an interface ID. Show information for all ports. auto—Turns on the device discovery protocol and applies power to the device. Shows Yes for ports enabled to support PoE (the default) and No for ports on which PoE is disabled. Toggle the hierarchy tree under Learn About Power over Ethernet (PoE). PSE Power Management: means the power supply management mode (automatic, preempt, non-preempt).
[pdf] The primary transmission and routing of data signals take place at the core layer only. The devices like high-capacity transmitters are placed in this. A core switch is a high-capacity, high-performance Layer 3 switch positioned at the physical backbone of an enterprise network. Engineered to aggregate massive volumes of data from distribution switches, it provides ultra-low latency and maximum throughput to ensure uninterrupted routing and packet. The layer that lies between the access layer and the core layer is known as the distribution or aggregation layer, while the backbone of the network is termed the core layer. Simply put, it's the kingpin that keeps your network humming. The access layer provides initial connections to end users.
[pdf] 
