D-Link DGS-1008P, Руководство пользователя

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D-Link Switch User Manual
7
Understanding The Switch’s Features
Cable Diagnostics
When the DGS-1008P is booting up, the Switch will scan all the ports to determine the status of the cable
connections. The diagnosis results will be displayed through the port LEDs immediately after the port scan has
finished. The port LED color indicates the following:
Solid green: A Gigabit connection was detected and there are no issues with the cable.
Solid amber: No connection or, bad cabling.
The quality of the used cable will also impact the diagnosis results. A Gigabit connection may be slowed down
to 10/100 Mbps as a result of using incorrect or bad quality Ethernet cables. Twisted pair Cat 5e cable or better
is recommended for Gigabit Ethernet.
Power over Ethernet (PoE)
The DGS-1008P supports many PoE features to guarantee the safety and stability of the Switch and the
connected powered devices.
PoE Power Budget: The total PoE budget of the DGS-1008P is limited to a maximum of 68 watts to both
protect the Switch and to stabilize the power being transmitted to the PoE-powered devices. Because the
Switch’s total PoE budget is 68 watts, this means that only 2 IEEE 802.3at-compliant devices can be
simultaneously powered by the Switch at 30 watts each.
PoE Port Priority: The DGS-1008P is configured to have predefined PoE priorities for all PoE ports to prevent
events such as unexpected overloading on PoE ports. Lower port numbers have a higher priority for supplying
power, for example port 1 > port 2 > port 3 > port 4. When a PoE overload is detected, the power supply from
the higher number ports will be cut off first.
Guard Band: The DGS-1008P reserves a 2 watts Guard Band to prevent the power supply from exceeding
the PoE power budget. When the Switch detects the current PoE output has reached 66 watts, the PoE Max.
LED will light up solid red and the Switch will check the priority of each PoE port. In the meantime, if a new
PoE device is connected, the Switch will cut off the power of the port with the higher port number.
For example: When Port 3 to 4 are both feeding 30 watts of power to the attached clients (total PoE power
used = 60 watts), and a new powered device is connected to port 1 that is being supplied more than 6 watts
of power, the power supply from port 4 will be cut off.
Quality of Service (QoS)
The DGS-1008P supports 4 levels of transmission queues to prioritize important traffic. The Switch will check
the priority tags in the packets and map them into corresponding queues. The mapping rules are as follows:
For 802.1p tag:
Priority value 1 and 2 are mapped to queue 0 (lowest priority queue)
Priority value 0 (No 802.1p tag) and priority value 3 are mapped to Queue 1
Priority value 4 and 5 are mapped to queue 2
Priority value 6 and 7 are mapped to queue 3 (highest priority queue)
Power Saving
The DGS-1008P supports IEEE 802.3az Energy Efficient Ethernet (EEE), which constantly monitors all ports
for data transmission and will put inactive ports in sleep mode to save power.