D-Link DES-3250TG manual 802.1p User Priority, QOS Output Scheduling

D-Link DES-3250TG Standalone Layer 2 Switch

802.1p User Priority

The DES-3250TG allows the assignment of a Class of Traffic to each of the 802.1p priorities.

Click 802.1p user_priority in the QoS folder on the Configuration menu:

Figure 7- 34. QoS Class of Traffic window

Once you have assigned a maximum number of packets and a maximum latency to a given Class of Service on the switch, you can then assign this Class to each of the eight levels of 802.1p priorities.

(QOS Output) Scheduling

Click QoS on the Configuration menu, and then click scheduling:

Figure 7- 35. QoS Output Scheduling window

The Max. Packets(O-255) field specifies the number of packets that a queue will transmit before surrendering the transmit buffer to the next lower priority queue in a round-robin fashion.

The Max. Latency(0-255) field specifies the maximum amount of time that a queue will have to wait before being given access to the transmit buffer. The Max. Latency(0-255) is a priority queue timer. When it expires, it overrides the round-robin and gives the priority queue that it was set for access to the transmit buffer.

There is a small amount of additional latency introduced because the priority queue that is transmitting at the time the Max. Latency(0-255) time expires will finish transmitting its current packet before giving up the transmit buffer.

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