HP ProCurve 6120G/XG Configuration Manual page 329

Table 12-1. Per-Port Outbound Priority Queues
802.1p Priority Settings in Tagged VLAN
Packets*
1 (low)
2 (low)
0 (normal)
3 (normal)
4 (medium)
5 (medium)
6 (high)
7 (high)
*The switch processes outbound traffic from an untagged port at the "0" (normal) priority level.
You can use GMB to reserve a specific percentage of each port's available
outbound bandwidth for each of the eight priority queues. This means that
regardless of the amount of high priority outbound traffic on a port, you can
ensure that there will always be bandwidth reserved for lower-priority traffic.
Since the switch services outbound traffic according to priority (highest to
lowest), the highest-priority outbound traffic on a given port automatically
receives the first priority in servicing. Thus, in most applications, it is neces­
sary only to specify the minimum bandwidth you want to allocate to the lower
priority queues. In this case, the high-priority traffic automatically receives all
unassigned bandwidth without starving the lower-priority queues.
Conversely, configuring a bandwidth minimum on only the high-priority out­
bound queue of a port (and not providing a bandwidth minimum for the lower-
priority queues) is not recommended because it may "starve" the lower-
priority queues.
Port Traffic Controls
Guaranteed Minimum Bandwidth (GMB)
Outbound Priority Queue for a Given Port
1
2
3
4
5
6
7
8
12-11