Lantronix
LSS2200-8P Install Guide
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9. If no PoE is available, note that LSS2200-8P per-input power consumption is not limited to the configured
budgets for PS1 and PS2. The LSS2200-8P per-input power consumption is dictated by relative input voltage
rather than by software configured power budgets. In practice, whichever supply provides higher voltage provides
the majority of the power to the switch, so if a lower power supply has a slightly higher voltage than a higher
power supply, the lower power supply will be utilized as the power source nearly all of LSS2200-8P power,
potentially exceeding the software defined budget for the lower power supply.
While dual power sources are connected, the LSS2200-8P will draw the majority of its power from the higher
voltage supply, even if the higher voltage supply has the lower budget, even if that consumption exceeds the
budget for the weaker supply. This occurs even from cold boot if the weaker supply is consistently regulated to a
higher voltage.
Advanced Steps
1. Get as much detail as possible regarding the symptom, including any system messages from the PoE switch.
For example, does a PD not power up at all, or does it power up briefly and then power down?
2. Determine if the trouble occurred on initial installation or after the PD had been working normally?
3. If the trouble started after the PD was working, what changed? Were there hardware or software changes?
4. Verify that the port is not shut down, disabled, or errored.
5. Verify that the Ethernet cable from the PD to the switch port is good.
6. Verify that the total cable length from the switch front panel to the connected PD is not more than 100 meters.
Some of the power from the switch port is dissipated in the cable due to wire resistance, especially on cables
as long as 100 meters. Only the remaining power is available to the PD. The 100-meter limit for twisted-pair
Ethernet cable assumes
a)
not more than four RJ-45 connection points in the transmission path,
b)
90 meters
of solid-strand Category 5 or 5e, and
c)
10 meters of flexible multistrand cable (2-to-5 meters of multistrand
Category 5 patch cords).
7. Verify that the PSE switch power budget can power the PD. If the switch power budget is depleted, additional
PDs will not power-on when connected to a PoE port. Verify that the switch power budget (available PoE) is
not depleted before or after the PD is connected. Verify that sufficient power is available for the PD type.
8. Verify if non-powered Ethernet devices can establish an Ethernet link on any port and that PoE devices do not
power up on the same port.
9. Review alarms reported previously by system messages.
10. If a working IP Phone or WAP intermittently reloads or disconnects from inline power, verify all electrical
connections from the switch to the PD. An unreliable connection results in power interruptions and intermittent
PD operation, such as PD disconnects and reloads.
11. Check for changes in the electrical environment at the switch site. What is happening at the PD when the
disconnect occurs? Check for error messages reported by the switch at the same time of the disconnect.
12. Verify an IP Phone is not losing access just before a reload occurs (a network problem, not a PoE problem).
13. Pre-standard and post-standard VoIP phones may use different detection and connect / disconnect methods.
Note that PD detection occurs when an Ethernet device is first connected to a PoE port. If a non-PoE device
is connected to a PoE port, detection is deactivated. If the non-PoE device is later disconnected and replaced
by a PD, the switch may not detect it immediately.
14. Verify that the PD is not causing an overcurrent condition on the port. Specifically, does the VoIP phone
initially power on and then disconnect? If so, the problem may be an initial current surge that exceeds a
current-limit threshold for the switch port. Some PDs may have excessive “surge in” current when first
connected to a PoE port. The switch initially provides power to the port, and then quickly removes power due
to a momentary overcurrent condition. The PD starts to power up, but then quickly powers down.