A solution that allows to supply electricity over standard Ethernet cables is known as
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What is Power over Ethernet?Power over Ethernet (PoE) is a set of standardized protocols that enables limited amounts of electrical power to be delivered over an Ethernet cable to a compatible device. The standards describe that a PoE system consists of two elements, the Power Sourcing Equipment (PSE) and one or more Powered Devices (PD). A Powered Device, once connected to Power Sourcing Equipment, does not need a dedicated power supply because the PSE supplies the power via the Ethernet cable. Usually, the PSE is an Ethernet access switch at the edge of the network. But it can also be a dedicated device, like a power injector, that adds the PoE to a non-powered Ethernet cable or media converter equipped with a PoE port. The Powered Device can be any type of network equipment: wireless Access Point, VoIP phone, IP camera, lighting system, or any other IoT device or sensor.
 Non-PoE Device Connection
PoE Switch-Based Connection
PoE Injector-Based Connection
Media Converter-Based ConnectionWhat are the advantages of PoE Technology?CostInstalling PoE devices lowers costs because separate power supplies and cables are not required—only a connection to an Ethernet port on the PSE. Upgrading a standard Ethernet network to support PoE only requires replacing the access switch, the other physical infrastructure can stay the same. ReliabilityPower failures are a leading cause of reliability problems in any network. Battery backup units reduce dependency on continuous power and increase the reliability of active devices. However, this approach can be expensive in a large network, requiring that all active devices connect to a battery backup unit. By delivering PoE instead, the cost is minimized by connecting only the access switch to the battery backup. During a power outage, the switch and all the connected PoE devices stay powered. FlexibilityPoE switch interfaces can connect to PoE or non-PoE devices without any restriction. Once a PoE switch is in place, it is possible to connect a PoE or non-PoE device to the Ethernet port. The only limitation is that the total PoE power requirements are within the power budget of the switch. How much power can PoE supply?The amount of PoE power that a switch can supply is dependent on two things:
The first value determines if a powered device is compatible with the port of a specific switch. The second value indicates how many powered devices can connect to the same switch. PoE Power ClassesThe maximum power supplied by a single port depends on the switch's capabilities, as defined by international standards (such as IEEE 802.3at and IEEE 802.3bt). These rules dictate that a switch or injector can't supply more power than the standard allows. The standards define four power level types for individual PoE ports: Type 1 (called PoE)Maximum power per port is 15W. (Allowing for losses through the cable, the max power available at the PD is 12.95W) Type 2 (known as PoE+)Maximum power available for each port is 30W (or up to 25.50W at the PD) Type 3 (called 4PPoE, Ultra PoE, UPOE)Maximum per port power is 60W (which equates to 51W at the PD) Type 4 (called Ultra PoE, UPOE)Maximum power available for each port is 100W (with up to 71W available at the PD) For a reliable PoE solution, the PD's power requirements must match the capabilities of the PSE's port. What is a Power Budget?The PoE power budget is the maximum PoE power a PSE can supply to all of its PoE ports. The budget dictates how many connected PDs the switch can power. If the PDs draw too much power from the PSE, it may cause an error condition that restricts power to some PDs. Some models of Allied Telesis PoE switches have removable power supplies that enable the PoE budget to be varied according to requirements. For example, the x930 series switches have three types of power supply modules that can be "hot-swapped" (i.e. changed while the switch is being used without interrupting traffic, provided another power supply is installed):
So by changing the model and number of power supplies installed in the switch, the PoE budget of the x930 series switches can be adjusted from 380W to a massive 1440W (that's 30W per port on all 48 ports!) It is important to note that most PSEs use the PoE Type to calculate the power consumption, not the actual PD consumption. This means that even if a PD is consuming only 20W, the PSE assumes that it is a Type 2 device and allocates it 30W from its PoE power budget. (For a solution to this, see PoE Power Budget Override below.) Smart Power Budget FeaturesAllied Telesis has been developing PoE products ever since the first standards were published. We've used this experience to create some useful features that make using PoE more flexible and reliable: PoE Power Budget OverrideInstead of allowing the switch to determine the PD power consumption using PoE Type, our switches enable you to specify the maximum power a port can supply. This optimizes the amount of power allocated to each device so the power budget can support more PDs per switch. Dynamic Power AllocationSome Allied Telesis switches can calculate their power budgets based on the actual power consumption of the attached PDs. So, the budget reflects the real-time power requirements of the connected PDs, and no manual configuration is required. PD PriorityIf the PDs exceed the PSE power budget, the PSE will remove power from some PDs to protect itself from damage. Our switches allow you to allocate a priority to each of the PDs so you can choose those to sacrifice first to protect your most critical services. Continuous PoEUsually, when the switch is rebooted (for a firmware upgrade, for example), the PoE power is interrupted until the switch is back online. Continuous PoE maintains power throughout the reboot to minimize disruption and keep PDs operational. Read more here. Which of the following protocols provide protection against switching loops?Answer is A.
Spanning Tree Protocol (STP) prevents switching loop problems and should be enabled.
Which of the following answers refers to a type of routing protocol that determines the best route for data packets based on the lowest number of hops?Which of the answers listed below refers to a type of routing protocol that determines the best route for data packets based on the lowest number of hops? A hybrid routing protocol combines the features of distance-vector and link-state routing protocols.
What are the characteristic features of the 100basetx Ethernet standard?Main characteristics of 100Base-TX FastEthernet are listed below. Operating speed of FastEthernet is 100 Mbps. Similar to other Ethernet standards, 100Base-TX uses baseband signals to transfer data. FastEthernet supports a maximum distance 100 meters between the network switch and the client computer.
Which of the devices listed below is used for separating broadcast domains?Routers and other higher-layer devices form boundaries between broadcast domains.
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