IEEE 802.1Q VLANs
143
power to ports set for a lower priority. If power is dropped to low-priority
ports and later the power demands on the switch fall back within its budget,
the dropped power is automatically restored.
Switch power budget
You can define a maximum PoE power budget for the switch (power
available to all switch ports) so that power is centrally managed, preventing
overload conditions at the power source. If the power demand from devices
connected to the switch exceeds the power budget setting, the switch uses
port power priority settings to limit the supplied power.
Port PoE power
If a device is connected to a switch port and the switch detects that it
requires more than the power budget of the port, no power is supplied to
the device (that is, the port power remains off).
If the power demand from devices connected to switch ports exceeds the
power budget set for the switch, the port power priority settings are used to
control the supplied power. For example:
•
If a device is connected to a low-priority port and causes the switch to
exceed its budget, port power is not turned on.
•
If a device is connected to a critical or high-priority port and causes
the switch to exceed its budget, port power is turned on, but the switch
drops power to one or more lower priority ports.
Power is dropped from low-priority ports in sequence starting from port
number 12.
IEEE 802.1Q VLANs
In large networks, routers are used to isolate broadcast traffic for each
subnet into separate domains. The switch provides a similar service at Layer
2 by using Virtual Local Area Networks (VLANs) to organize any group of
network nodes into separate broadcast domains. VLANs confine broadcast
traffic to the originating group and can eliminate broadcast storms in large
networks. They also provide a more secure and clean network environment.
An IEEE 802.1Q VLAN is a group of ports that can be located anywhere in
the network, but communicate as though they belong to the same physical
segment.
VLANs help to simplify network management by allowing you to move
devices to a new VLAN without having to change any physical connections.
VLANs can be easily organized to reflect departmental groups (such as
Marketing or R&D), usage groups (such as e-mail), or multicast groups
(used for multimedia applications such as videoconferencing).
SMB
Using the Nortel Business Ethernet Switch 50 Series
NN47924-301
01.01
Standard
1.00
October 2006
Copyright © 2006, Nortel Networks
Nortel Networks Confidential
.
Summary of Contents for BES50FE-12T PWR
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