Class of Service Configuration 3

Class of Service Configuration

Class of Service (CoS) allows you to specify which data packets have greater precedence when traffic is buffered in the switch due to congestion. This switch supports CoS with eight priority queues for each port. Data packets in a port’s high-priority queue will be transmitted before those in the lower-priority queues. You can set the default priority for each interface, and configure the mapping of frame priority tags to the switch’s priority queues.

Layer 2 Queue Settings

Setting the Default Priority for Interfaces

You can specify the default port priority for each interface on the switch. All untagged packets entering the switch are tagged with the specified default port priority, and then sorted into the appropriate priority queue at the output port.

Command Usage

•This switch provides eight priority queues for each port. It uses Weighted Round Robin to prevent head-of-queue blockage.

•The default priority applies for an untagged frame received on a port set to accept all frame types (i.e, receives both untagged and tagged frames). This priority does not apply to IEEE 802.1Q VLAN tagged frames. If the incoming frame is an IEEE 802.1Q VLAN tagged frame, the IEEE 802.1p User Priority bits will be used.

•If the output port is an untagged member of the associated VLAN, these frames are stripped of all VLAN tags prior to transmission.

Command Attributes

•Default Priority20 – The priority that is assigned to untagged frames received on the specified interface. (Range: 0 - 7, Default: 0)

•Number of Egress Traffic Classes – The number of queue buffers provided for each port.

20. CLI displays this information as “Priority for untagged traffic.”

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