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Forum Discussion
Managed PoE Switch - 4 Port (Power through spare pairs only)
Hi,
I am looking for a managed PoE switch(midspan device), 802.3af compliant, 10/100Mbps 4 port switch, which can send power through spare pairs only.
I intend to measure current delivered to the PD device from each port of the switch. Please let me know your suggestions.
3 Replies
Is this an academic project or more?
Most Web managed, Smart managed, or managed switches provide the power information in the Web UI, sometimes in SNMP, ... So why bother about things you have no control - because you don't know on how the PD does negotiate things.
No. This is not an academic project.
We have developing a PoE PD device, and we are now building a FCT fixture to test the PoE PD.
I have following ain requirements here:
1. 4 downlink PoE Port
2. PoE switch should be able to individually turn on/off downlink Ports
3. PoE load current through each should be measurable
4. PoE switch is used to power an 802.3af compliant PD.
Kindly suggest me the most cost effective solution for my reqirement.
Requirement #1, #4: GS110TPP - no models with less PoE+ ports and SNMP AFAIK (I'm not Netgear!)
Requirement #2, #3: SNMP controls (GS110TPP - download -> MIB -> POWER-ETHERNET-MIB) allows enable/disable PoE, reading current PSE consumption in Watt delivered to the port, reading and setting power pairs, ... Further on, there is some more information available e.g. on the PSE state diagram, negotiated power pairs
Reading (e.g. on auto negotiation) or setting the power pairs (Note: GbE does use all pairs for signals - this might allow setting the mode so you can loop-out the non-signal pairs over measuring equipment):
Requirement set to outband::pethPsePortPowerPairs OBJECT-TYPE
SYNTAX INTEGER {
signal(1),
spare(2)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"Describes or controls the pairs in use. If the value of
pethPsePortPowerPairsControl is true, this object is
writable.
A value of signal(1) means that the signal pairs
only are in use.
A value of spare(2) means that the spare pairs
only are in use."
REFERENCE
"IEEE Std 802.3af Section 30.9.1.1.4 aPSEPowerPairs"
::= { pethPsePortEntry 5 }
Requirement #2:
pethPsePortAdminEnable OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"true (1) An interface which can provide the PSE functions.
false(2) The interface will act as it would if it had no PSE
function."
REFERENCE
"IEEE Std 802.3af Section 30.9.1.1.2 aPSEAdminState"
::= { pethPsePortEntry 3 }
Requirement #3: Depending on the measurement quality, this might be already sufficient:
...
pethMainPseConsumptionPower OBJECT-TYPE
SYNTAX Gauge32
UNITS "Watts"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"Measured usage power expressed in Watts."
::= { pethMainPseEntry 4 }...
Enough fre consulting for now - send beer!Regards,
-Kurt.
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