Huawei AR150 Series Configuration Manual page 139

Huawei AR150&200&1200&2200&3200 Series Enterprise
Routers
Configuration Guide - Device Management
PoE Power Management Mode
When PDs connected to the PSE increase, the PoE power supply cannot provide power for all
PDs. Therefore, the PSE should manage the power supply. Power management is classified into
two modes: automatic and manual.
l
l
Power Supply Mode of PSEs
As defined in IEEE standard, PSEs provide power for PDs and are classified into MidSpan (the
PoE module is installed out of the device) and Endpoint (the PoE module is integrated to device)
PSEs. Huawei' PoE modules are Endpoint PSEs. The Endpoint PSE is compatible with 10Base-
T, 100Base-TX, and 1000Base-T interfaces. The Endpoint PSE is more widely used than the
Midspan PSE.
Endpoint PSEs can work in Alternative A (line pair 1/2 and line pair 3/6) and Alternative B
(Line pair 4/5 and line pair 7/8) power supply modes according to different copper line pairs.
l
l
Generally, a standard PD supports the two modes, whereas the PSE only needs to support one
mode. Huawei PSE supports only Alternative A.
LLDP Power Capability Negotiation
Originally, a device analyzes the current that is transmitted between the PSE and PD to classify
PDs. Besides current analysis, the device supports Link Layer Discovery Protocol (LLDP) power
capability negotiation. IEEE 802.1ab defines the optional TLV: Power via MDI TLV. The Power
via MDI TLV is encapsulated in LLDP packets, and is used for discovery and advertisement of
MDI power capabilities, and network management.
When the PSE detects a PD, the PSE and PD periodically send LLDP packets with the defined
TLV to each other. The peer end records the information in LLDPDIs for information exchange.
Issue 05 (2014-01-16)
Automatic mode: The PSE automatically powers on or powers off PDs based on power
priorities. You can configure a power priority of each interface as Critical, High, or Low
based on the importance of the PD connected to each interface. When providing power
nearly at full capacity, the PSE provides power first for the PD connected to the interface
of Critical priority and then provides power for the PD connected to the interface of High
priority. If multiple PoE interfaces have the same priority, the system first supply power to
the PDs connected to the interfaces with smaller interface numbers.
Manual mode: You can manually power on or power off interfaces. In manual mode, the
PSE provides power for an interface without considering the priority. Powering on or
powering off a single interface does not affect the power supply status. When providing
power nearly at full capacity, the PSE cannot continue to power on a new PD.
Alternative A mode: Power is transmitted over pairs of lines that transmit data.
The PSE provides power for the PD over copper line pairs connected to pins 1 and 2 and
pins 3 and 6. Pins 1 and 2 use the positive voltage and pins 3 and 6 use the negative voltage.
10Base-T and 100Base-TX interfaces use copper line pairs connected to pins 1 and 2 and
pins 3 and 6 to transmit data, and 1000Base-T interfaces use four line pairs to transmit data.
DC power and data frequency are independent. Therefore, the power and data can be
transmitted in one pair of lines.
Alternative B mode: Power is transmitted over idle pairs of lines.
The PSE provides power for the PD over copper line pairs connected to pins 4 and 5 and
pins 7 and 8. Pins 4 and 5 use the positive voltage and pins 7 and 8 use the negative voltage.
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
6 PoE Configuration
130