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Quality of Service: Managing Bandwidth More Effectively
Globally-Configured QoS
Global VLAN-ID Classifier
Global QoS Classifier Precedence: 5
The global VLAN-ID (VID) classifier allows you to use up to 4094 VLAN IDs to
match packets. When a particular VLAN-ID classifier has the highest prece-
dence in the switch, traffic received in the VLAN i s marked with the configured
priority level. You can configure different global VLAN-ID classifiers to mark
packets with different priority levels.
Options for Assigning Priority. The global QoS packet-marking options
for packets that carry a specified VLAN-ID include:
■ 802.1p priority
■ DSCP policy (Assigning a new DSCP and an associated 802.1p priority;
inbound packets must be IPv4.)
For information on QoS operation when other global QoS classifiers match
the same traffic, see to “Globally-Configured Packet Classification” on page
6-12.
Configuration A global VLAN-ID classifier marks priority levels only in packets received on
Notes
static VLANs. Packets received in a dynamic VLAN created by GVRP operation
are not marked by a global VLAN-ID classifier.
The VLAN ID used as a global QoS classifier must currently exist on the switch.
If you remove a VLAN from the switch, all global QoS configurations that use
the VLAN ID for packet marking are also removed.
Assigning a Priority for a Global VLAN-ID Classifier
This global QoS packet-marking option assigns a priority to all outbound
packets having the specified VLAN-ID (VID). You can configure this option by
either specifying the VLAN-ID ahead of the qos command or moving to the
VLAN context for the VLAN you want to configure for priority.
Syntax: vlan < vid > qos priority < 0 - 7 >
Configures an 802.1p priority for outbound packets belong-
ing to the specified VLAN. This priority determines the
packet’s queue in the outbound port to which it is sent. If the
packet leaves the switch on a tagged port, it carries the 802.1p
priority with it to the next downstream device. You can
configure one QoS classifier for each VLAN-ID. (Default: No-
override)
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