Quality of Service (QoS): Managing Bandwidth More Effectively
Introduction
But if the packet is in a VLAN-tagged environment, then the above setting is
also added to the packet as an 802.1p priority for use by downstream devices
and applications (shown in table 6-3). In either case, an IP packet can also
carry a priority policy to downstream devices by using DSCP-marking in the
ToS byte.
Table 6-3.Mapping Switch QoS Priority Settings to Device Queues
Priority Setting Outbound Port 802.1p Priority Setting Added Queue Assignment in Downstream Devices With:
Queues in the
Switch
to Tagged VLAN Packets
Leaving the Switch
8 Queues 3 Queues 2 Queues
1
2
Queue 1 1 (low priority)
2
Queue 1
Queue 2
Queue 1
Queue 1
0
3
Queue 2 0 (normal priority)
3
Queue 3
Queue 4
Queue 2
4
5
Queue 3 4 (medium priority)
5
Queue 5
Queue 6
Queue 7
Queue 8
Queue 3
Queue 2
6
7
Queue 4 6 (high priority)
7
Note On Using
Multiple
Criteria
Classifiers for Prioritizing Outbound Packets
ProCurve recommends that you configure a minimum number of the available
QoS classifiers for prioritizing any given packet type. Increasing the number
of active classifier options for a packet type increases the complexity of the
possible outcomes and consumes switch resources.
Packet Classifiers and Evaluation Order
The switches covered by this chapter provide six QoS classifiers (packet
criteria) you can use to configure QoS priority.
6-9
