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Redundant Power Supply Capability
The switch has power supply redundancy capability when connected to an optional
SecureStack C2RPS‐POE external redundant power supply (RPS). If the internal power
supply fails, the RPS assumes the entire load of the switch without interrupting network
traffic. The internal power supply and RPS each have their own AC power connection,
which enables the connection of each power supply to a different AC power circuit for
additional AC power source redundancy.
PoE (Power over Ethernet) Support
The switch is 802.3af compliant, which means it can provide power over Ethernet cable
connections from its 48, RJ45 front panel connectors to PDs in the network.
Power over Ethernet (PoE) refers to the ability to provide 48 Vdc power to a powered
device using the same Ethernet cabling that provides data. Modern Ethernet
implementations employ differential signals over twisted pair cables. This requires a
minimum of two twisted pairs for a single physical link. Both ends of the cable are
isolated with transformers blocking any DC or common mode voltage on the signal pair.
PoE exploits this fact by using two twisted pairs as the two conductors to supply a direct
current. One pair carries the power supply current and the other pair provides a path for
the return current. While several proprietary legacy implementations of PoE have been
deployed by LAN equipment vendors, in 2003 the IEEE published the IEEE 802.3af‐2003
specification, which is part of the 802.3 suite of standards.
The switch is fully compliant with the IEEE 802.3af standard. It supports the standard
resistor‐based detection method, as well as AC disconnect capability. The switch is also
capable of supplying 7.5 watts of power to all ports simultaneously. Support is also
provided for the 802.3af‐defined maximum of 15.4 watts.
Each PD (Powered Device) has a PDC (Powered Device Classification) that is transmitted
to the switch for power management purposes. Table
classifications and the associated power ranges.
Table 1-1 Powered Device Classifications
Class
None
1
2
3
4
1‐1 on page 1‐5 lists the
Usage
Default
Optional
Optional
Optional
Not Allowed
PoE (Power over Ethernet) Support
PD Maximum Power Range
Usage
0.44 to 12.95 Watts
0.44 to 3.84 Watts
3.84 to 6.49 Watts
6.49 to 12.95 Watts
Reserved for Future Use
SecureStack B2 Installation Guide 1-5
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Troubleshooting
