3Com 3CNJ220-CRM, Руководство пользователя

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Changing Device Configuration 45
transmissions in the Property window because it is unlikely that the IntelliJack will
drop any Ethernet Packets.
If you believe that the IntelliJack is dropping Ethernet packets, you may want to
configure the Counter Mode to count received errors (Rx Errors) and transmission
collisions (Tx Collisions). This will give you a good sense of whether packets are
actually being dropped.
10 To change the Power Forwarding setting, click the box and select an option from
the drop list.
IEEE 802.3af is the recognized standard for Power over Ethernet (POE) and the
default setting. More and more network devices that are POE capable are
adhering to this standard.
The IntelliJack’s Power over Ethernet capability also lets you forward power to a
standards-compliant device plugged into Port 1 of the NJ220. The default setting
of the NJ220 is auto-detect. We recommend that you keep this setting as part of
your configuration to ensure that power will only be forwarded to devices capable
of receiving it.
The IEEE802.3af standard requires a powered device to present a signature to the
power sourcing equipment. The power sourcing equipment will check this
signature and will only apply power to the line when it sees the correct signature.
If you want to ensure that power will not be forwarded at all, however, you could
select Force power OFF to any device connected to Port 1.
Select Force power ON if you always want to apply power to any device plugged
into Port 1. This option would let you power devices plugged into Port 1 that do
not have the signature required by IEEE802.3af-compliant power sourcing
equipment.
WARNING: By forcing power ON, you may damage equipment that is
inadvertently plugged into Port 1, such as a device that is not designed to
handle 48V.