Ericsson ECN330, User Manual

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Introduction to the ECN330-switch
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1553-KDU 137 365 Uen D 2006-06-16
2.2 Hardware Description
2.2.1 Power-over-Ethernet Ports
All of the 24 10BASE-T/100BASE-TX RJ45 ports support PoE capability and
can supply up to 23.1 W per port to connected EDA nodes.
The PoE enables DC power to be supplied to the connected nodes through the
Ethernet cable. IP DSLAMs attached to a port can directly draw power from the
ECN330-switch over the Ethernet cable without requiring a separate power
source. The ECN330-switch automatically detects an EDA node by its
authenticated PoE signature and senses its required load before turning on DC
power to the port. An electrical port of ESN108 (which is also a PoE node) can
also be connected to the ECN330-switch. The sense circuit in both nodes
(ECN330 and ESN108) will sense that no power is required. This detection
mechanism also prevents damage to other network equipment that is not an
EDA node.
The ECN330-switch delivers power to the IP DSLAM using the two wire pairs in
UTP or STP CAT 5 cable that are not used for 10BASE-T/100BASE-TX
connections (for details see the ECN330 Installation Guide). Each line is 100%
individually controlled with an auto-detect circuit that opens up if a load within
the EDA-specified range is detected, and shuts down if the load exceeds the
limit of 23.1 W. Each line is filtered for surge currents and has a 4 ms backup
reservoir, should short voltage dropouts occur.
The ECN330-switch can provide up to 600 mA continuously on each 10/100
Mbps port, or up to 23.1 W of power. However, taking into account some power
loss over the cable run, the amount of power that can be delivered to an EDA
node is about 21 W. If a device draws more than 625 mA from a port, an overload
condition occurs and the port turns off the power.
These ports also support automatic MDI/MDI-X operation, so straight-through
cables can be used for all network connections to PCs or servers, or to other
switches or hubs.
The ports also support auto-negotiation, so the optimal transmission mode
(half or full duplex), and data rate (10 or 100 Mbps), or flow control method
(IEEE 802.3x, Back-Pressure or none) can be selected automatically, if this
feature is also supported by the attached device. If a device connected to one of
these ports does not support auto-negotiation, the correct speed will be sensed
by the port, but the transmission mode will by default be half duplex.