HP 445946-001 Using 802.1p priorities to provide QoS, DSCP, Priority, Default PHB, Service Level, Class Selector, 802.1p Priority, Quality of Service

Quality of Service

•Class Selector (CS)—This PHB has eight priority classes, with CS7 representing the highest priority, and CS0 representing the lowest priority, as shown below. CS PHB is described in RFC 2474.

Table 18 Class selector priority classes

Priority	Class Selector	DSCP
Highest	CS7	56
	CS6	48
	CS5	40
	CS4	32
	CS3	24
	CS2	16
	CS1	8
Lowest	CS0	0

QoS levels

The following table shows the default service levels provided by the switch, listed from highest to lowest importance:

Table 19 Default QoS service levels

Service Level	Default PHB	802.1p Priority
Critical	CS7	7
Network Control	CS6	6
Premium	EF, CS5	5
Platinum	AF41, AF42, AF43, CS4	4
Gold	AF31, AF32, AF33, CS3	3
Silver	AF21, AF22, AF23, CS2	2
Bronze	AF11, AF12, AF13, CS1	1

Using 802.1p priorities to provide QoS

The HP 10GbE switch software provides Quality of Service functions based on the priority bits in a packet’s VLAN header. (The priority bits are defined by the 802.1p standard within the IEEE 802.1q VLAN header.) The 802.1p bits, if present in the packet, specify the priority given to packets during forwarding. Packets with a numerically higher (non-zero) priority are given forwarding preference over packets with lower priority.

Packets with a priority mapped to a higher Class of Service (COS) and COS queue (COSq) weight are given forwarding preference over packets with priority mapped to a lower COS and COSq weight. The scheduling scheme is Weight Round Robin (WRR), with user-configurable weight from 0 to 15 for a COSq. The switch can be configured with either two or eight output Class of Service queues (COSq).

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