Functionality of the SecureStack RPS Systems

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Article ID: 5741 

Products
SecureStack C3
SecureStack C2
SecureStack B3
SecureStack B2
SecureStack A2
C2RPS-POE
C2RPS-PSM
C2RPS-CHAS2
C2RPS-CHAS8
C2RPS-SYS 

Protocols/Features
PoE
RPS 

Symptoms
"Not Installed and/or Not Operating"
"Installed and Not Operating" 

Cause
Two separate Reserve Power Systems may be used with the SecureStack products: one to provide reserve power to PoE (Power over Ethernet) switch models and their attached PoE clients, and the other to provide reserve power to non-PoE switch models. 

Solution 

For PoE use, these are the components:
  • C2RPS-POE - Standalone 500-watt (130 watts @ 12V DC for switch operation, 370 watts @ 48V DC for PoE client operation) power supply with one 110V AC power cord for attachment to the electrical source and one 12V/48V DC cable for attachment (not hot-swappable) to a "P"-suffixed (example: C2H124-48P) switch.
The DC Power/Monitor cable attaches to 15-pin D-type connectors located on the rear of a C2RPS-POE and the rear of a SecureStack PoE switch unit. This cable is keyed differently from the non-PoE cable (see below), and is not interchangeable with it. 

For non-PoE use, these are the components:
  • C2RPS-PSM - 150-watt power supply with one 110V AC power cord for attachment to the electrical source and one 12V DC cable for attachment to a SecureStack switch of model other than the PoE models stated above.
  • C2RPS-CHAS2 - Passive, rack-mount chassis for housing up to two C2RPS-PSM power supplies
  • C2RPS-CHAS8 - Passive, rack-mount chassis for housing up to eight C2RPS-PSM power supplies
  • C2RPS-SYS - One C2RPS-CHAS8 with one C2RPS-PSM power supply (and cord/cable) included
The DC Power/Monitor cable attaches to 15-pin D-type connectors located on the rear of a C2RPS-PSM and the rear of a SecureStack non-PoE switch unit. This cable is keyed differently from the PoE cable (see above), and is not interchangeable with it. 

Q&A 

Q. Does the C2RPS-PSM require the use of the C2RPS-CHAS2 or C2RPS-CHAS8? 
A. No. The C2RPS-CHAS2 and C2RPS-CHAS8 are merely passive racking options for one or more C2RPS-PSMs. 

Q. Does the RPS serve as a UPS in the event of power failure?
A. Since the RPS requires a constant source of 110-volt AC Power to properly function, it does not serve as an Uninterruptable Power Supply. Rather, it serves as a Reserve Power Supply in the event the physical power supply mounted within the SecureStack goes into a fail state. There is no disruption to switch operation when the power feed reverts to the RPS or back to the primary supply. 

Q. Can the RPS serve as a supplementary power source which can be aggregated with standard AC power to provide more than the standard wattage (5418) to each PoE switch unit? 
A. No. It is redundant to the on-board power supply, and used only in the event of primary power failure. 

Q. What determines a "fail state" for either the internal/primary power supply or the external/reserve power supply?
A. Both the internal and external supplies have a POWER OK hardware signal, which when true (on, asserted) indicates that both the AC power feed and the DC power output are within specifications. A power supply is considered to be in a fail state when the POWER OK hardware signal for that supply is false (off, not asserted). 

Q. Which component makes the decision regarding when to fail over or fail back?
A. Within each of the switches there are what are referred to as "OR"ing diodes. These diodes connect the internal/primary and external/reserve supplies to the main power logic in the switch. There is no digital logic involved in this process other than status reporting logic which monitors and reports the status of the POWER OK signal from each of the supplies and their output voltages. 

Q. When does the RPS take over for the primary power supply?
A. The RPS takes over for the primary supply when the primary supply's POWER OK is false and the RPS's POWER OK is true. 

Q. When does the RPS return control to the primary power supply?
A. The RPS returns control to the primary power supply when the primary supply'sPOWER OK is true or the RPS's POWER OK is false. If both power supplies are in a POWER OK false state, the switch will lose power and fail to operate. 

Q. How are power outages handled?
A. A power outage will cause SecureStack switch power loss if experienced by both primary and reserve power supplies. The use of a UPS System on the reserve and/or primary power feed is encouraged in order to avoid such possibilities. 

Q. How are brown-outs handled?
A. A severe brownout could cause short-term power loss if experienced by both primary and reserve power supplies. The use of a UPS System on the reserve and/or primary power feed is encouraged in order to avoid such possibilities. 

Q. Might the power supply feed "flap" back and forth?
A. If the switch and the RPS are on separate power grids or the switch has no UPS but the RPS does, then an unstable power condition on the switch could have the RPS taking over power, relinquishing it, then taking it over again, repeatedly, for the duration of the instability. This is within design specifications, with no expectation of switch disruption. 

Q. What are the indicators on the host SecureStack switch, and on the C2RPS-PSM, under various RPS operation state scenarios?
A. This chart explains the indicators seen when there is no PSM cable attached to the switch, when a PSM cable is attached to the switch but does not lead to a ready PSM, when a PSM is installed but not providing backup power, and when a PSM is installed and actively providing backup power: 

     Scenario         SecureStack Switch                        C2RPS-PSM 
RPS LED 'show system' Power LED
PS2-Status

No PSM cable off "Not Installed and/or Not Operating" n/a
PSM cable, no PSM off "Installed and Not Operating" n/a
PSM installed off "Ok" green
PSM active amber "Ok" green

Q. Are the components hot-swappable?
A. Yes. 

Q. How long are the power cables?
A. For both PoE and non-PoE applications, the AC power cords are 2 meters (6.6 feet) in length and the DC power cables are 1 meter (3.28 feet) in length. 

Q. What are the newer RPS products?
A. These are outlined in 13569

Manuals:For more information, please review the SecureStack Installation Guide relevant to your switch model.
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