“Fast-PoE and Perpetual-PoE are new standards or not?”
The “Power over Ethernet” technology, or “PoE” for short, has firmly entered our life and is inextricably linked with the overwhelming majority of installations of IP-telephony, video surveillance and wireless networks. The last update of the IEEE 802.3 standard, in part of the familiar PoE, was conducted in 2012. Then, during the next revision of the standard, the adopted additions were included in it, including 802.3at-2009 (Power over Ethernet enhancements - 25.5 W), known to us as “PoE +”. Today, products with the support of Fast-PoE and Perpetual-PoE technologies are entering the market of network switches. Whether these capabilities of the switches are part of the standard or not, let's try to understand our article.
Immediately, the IEEE 802.3 standard includes the following approved additions with regards to PoE:
802.3af || 2003-06 || Power over Ethernet (15.4 W)
802.3at || 2009-09 || Power over Ethernet enhancements (25.5 W)
802.3au || 2006-06 || Isolation requirements for Power over Ethernet (802.3-2005 / Cor 1)
802.3bt || 2018-09 || Third generation Power over Ethernet with up to 100 W using all 4 pairs of I / T applications (eg lighting, sensors, building automation).
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The 802.3af / at / au standards are successfully implemented and widely used; 802.3bt (PoE ++) was ratified only last year and is beginning to conquer its niche in the market. Characteristics of standards:
Also in the current 2019, the IEEE 802.3cq working group plans to make editorial and technical corrections, clarifications and explanations to section 33 of the standard (IEEE Std 802.3-2018 Clause 33), without adding new features. This is necessary to improve the accuracy and clarity of the standard.
802.3cq || (TBD) || Power over Ethernet over 2 pairs (maintenance) - scheduled for summer 2019
Actually, none of the above additions to the standard describes such concepts as “Fast-PoE” and “Perpetual-PoE”. The point is that the standard describes the requirements and the counter work of the PSE, PD and cable lines (“Power Source Equipment”, “Powered Device”). Something like the diagram below:
PSE, in the most general case, is any switch with PoE. The switch architecture, which is familiar to us, consists of “Control Plane” and “Data Plane”, and in the case of PoE, an independent PoE controller is also added to this scheme. It is the PoE controller that is responsible for the classification of PD and the supply of voltage to the line. The logical boundary in this scheme passes just through the PoE controller. So on the one hand this border we have the PoE standard, which describes the work in the direction of the cable line, and on the other hand, we have nowhere described the operation of the same controller with the other elements of the switch and its operating system. That is, before it was thought that the PoE controller is powered and works 100% of the time, the switches never reboot and do not lose power. “Fast-PoE” and “Perpetual-PoE” technologies are an improvement of the switch operation, and are designed just to eliminate these gaps.
"Perpetual PoE" : saves power to the line during a soft reset ("warm reboot")
"Fast PoE" : provides power to the line after a reboot on power ("cold reboot") before the switch is fully loaded with OC
"Perpetual PoE"
Provides the ability to reboot switches while at the same time providing continuous power to devices connected to the PoE. Currently, a switch reboot results in a temporary loss of power on the ports, which leads to a complete reboot of all connected devices. This is very undesirable in working conditions. Perpetual PoE alleviates this unpleasant problem by continuing to provide continuous power through the PoE ports to external devices, even when the power supply switch reboots.
In network switches, the PoE subsystem is powered by the same power source as the switch itself. Power to each switch subsystem, including the PoE subsystem, is controlled by FPGA. Today, when the switch is rebooted by a command from the OS, the FPGA first turns off the power and then turns on all switch subsystems, including the PoE subsystem. When the PoE subsystem turns off, power is cut off on all ports, thereby disconnecting all connected devices. That is, while the switch itself is connected to the PSU and receives power from it, Perpetual PoE technology ensures that the FPGA will keep the PoE subsystem turned on and provide continuous power to all PoE ports on all connected devices, even when the switch OS is rebooted.
"Fast PoE"
The standard implementation of switches provided that after a power reset (“cold reboot”), PoE is fed into the line only after the switch loads its own OS and it sends instructions to the PoE controller. This usually occurs a few minutes after power is applied to the switch. “Fast PoE” is designed to provide power to PoE devices as soon as the switch is turned on. For this, the PoE settings are saved in the PoE controller EEPROM. When the switch is turned on, the PoE controller loads the last saved configuration from the EEPROM and starts automatically supplying power without waiting for the switch OS to boot. Within a few seconds, PD power will be resumed, and the PD and PSE will be loaded in parallel rather than in series. This minimizes the time of possible interruption of communication.
And although these improvements may seem rather prosaic from the client’s point of view, they consist of several very important changes to the switch architecture. As in the hardware - the PoE controller itself, and software - in the part of the FPGA code, which prevents the activation of the reset of the PoE subsystem, and the OS part of the switches, which controls the FPGA under the guise of "Perpetual PoE" control. It is also important to note that "Perpetual PoE" and "Fast PoE" are completely independent from each other, and from the PoE standard itself.
These improvements can be extremely popular and useful for projects of critical infrastructure, where disruption of work is always tolerated very painfully, both from a business point of view and from a security point of view.
As part of the Extreme Networks product line, ExtremeSwitching X465 series switches support Fast-PoE and Perpetual-PoE, as well as PoE ++ (802.3bt).
If you have questions, please contact our local Extreme Networks representative .
Immediately, the IEEE 802.3 standard includes the following approved additions with regards to PoE:
802.3af || 2003-06 || Power over Ethernet (15.4 W)
802.3at || 2009-09 || Power over Ethernet enhancements (25.5 W)
802.3au || 2006-06 || Isolation requirements for Power over Ethernet (802.3-2005 / Cor 1)
802.3bt || 2018-09 || Third generation Power over Ethernet with up to 100 W using all 4 pairs of I / T applications (eg lighting, sensors, building automation).
')
The 802.3af / at / au standards are successfully implemented and widely used; 802.3bt (PoE ++) was ratified only last year and is beginning to conquer its niche in the market. Characteristics of standards:
Also in the current 2019, the IEEE 802.3cq working group plans to make editorial and technical corrections, clarifications and explanations to section 33 of the standard (IEEE Std 802.3-2018 Clause 33), without adding new features. This is necessary to improve the accuracy and clarity of the standard.
802.3cq || (TBD) || Power over Ethernet over 2 pairs (maintenance) - scheduled for summer 2019
Actually, none of the above additions to the standard describes such concepts as “Fast-PoE” and “Perpetual-PoE”. The point is that the standard describes the requirements and the counter work of the PSE, PD and cable lines (“Power Source Equipment”, “Powered Device”). Something like the diagram below:
PSE, in the most general case, is any switch with PoE. The switch architecture, which is familiar to us, consists of “Control Plane” and “Data Plane”, and in the case of PoE, an independent PoE controller is also added to this scheme. It is the PoE controller that is responsible for the classification of PD and the supply of voltage to the line. The logical boundary in this scheme passes just through the PoE controller. So on the one hand this border we have the PoE standard, which describes the work in the direction of the cable line, and on the other hand, we have nowhere described the operation of the same controller with the other elements of the switch and its operating system. That is, before it was thought that the PoE controller is powered and works 100% of the time, the switches never reboot and do not lose power. “Fast-PoE” and “Perpetual-PoE” technologies are an improvement of the switch operation, and are designed just to eliminate these gaps.
"Perpetual PoE" : saves power to the line during a soft reset ("warm reboot")
"Fast PoE" : provides power to the line after a reboot on power ("cold reboot") before the switch is fully loaded with OC
"Perpetual PoE"
Provides the ability to reboot switches while at the same time providing continuous power to devices connected to the PoE. Currently, a switch reboot results in a temporary loss of power on the ports, which leads to a complete reboot of all connected devices. This is very undesirable in working conditions. Perpetual PoE alleviates this unpleasant problem by continuing to provide continuous power through the PoE ports to external devices, even when the power supply switch reboots.
In network switches, the PoE subsystem is powered by the same power source as the switch itself. Power to each switch subsystem, including the PoE subsystem, is controlled by FPGA. Today, when the switch is rebooted by a command from the OS, the FPGA first turns off the power and then turns on all switch subsystems, including the PoE subsystem. When the PoE subsystem turns off, power is cut off on all ports, thereby disconnecting all connected devices. That is, while the switch itself is connected to the PSU and receives power from it, Perpetual PoE technology ensures that the FPGA will keep the PoE subsystem turned on and provide continuous power to all PoE ports on all connected devices, even when the switch OS is rebooted.
"Fast PoE"
The standard implementation of switches provided that after a power reset (“cold reboot”), PoE is fed into the line only after the switch loads its own OS and it sends instructions to the PoE controller. This usually occurs a few minutes after power is applied to the switch. “Fast PoE” is designed to provide power to PoE devices as soon as the switch is turned on. For this, the PoE settings are saved in the PoE controller EEPROM. When the switch is turned on, the PoE controller loads the last saved configuration from the EEPROM and starts automatically supplying power without waiting for the switch OS to boot. Within a few seconds, PD power will be resumed, and the PD and PSE will be loaded in parallel rather than in series. This minimizes the time of possible interruption of communication.
And although these improvements may seem rather prosaic from the client’s point of view, they consist of several very important changes to the switch architecture. As in the hardware - the PoE controller itself, and software - in the part of the FPGA code, which prevents the activation of the reset of the PoE subsystem, and the OS part of the switches, which controls the FPGA under the guise of "Perpetual PoE" control. It is also important to note that "Perpetual PoE" and "Fast PoE" are completely independent from each other, and from the PoE standard itself.
These improvements can be extremely popular and useful for projects of critical infrastructure, where disruption of work is always tolerated very painfully, both from a business point of view and from a security point of view.
As part of the Extreme Networks product line, ExtremeSwitching X465 series switches support Fast-PoE and Perpetual-PoE, as well as PoE ++ (802.3bt).
If you have questions, please contact our local Extreme Networks representative .
Source: https://habr.com/ru/post/459226/
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