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Overview • The switches support the aggregate QoS model by enabling classification, policing/
metering, and marking functions on a per-port basis at ingress and queuing/scheduling
functions at egress.
• The switches support configuring QoS ACPs on all ports, using ACPs to ensure proper
policing and marking on a per-packet basis. Up to four ACPs per switch are supported in
configuring either QoS ACPs or security filters.
• Automatic QoS (Auto-QoS) greatly simplifies the configuration of QoS in voice-over-IP
(VoIP) networks by issuing interface and global switch commands that allow the detection
of Cisco IP phones, the classification of traffic, and egress queue configuration.
QoS Classification
Support at Ingress
• The switches support QoS classification of incoming packets for QoS flows based on Layer
2, Layer 3, and Layer 4 fields.
• The following Layer 2 fields (or a combination) can be used for classifying incoming
packets to define QoS flows: source/destination MAC address, or 16-bit Ethertype.
• The switches support identification of traffic based on Layer 3 type of service (ToS) field
DSCP values.
• The following Layer 3 and Layer 4 fields (or a combination) can be used to classify
incoming packets to define QoS flows: source/destination IP address, TCP source/
destination port number, or UDP source/destination port number.
QoS metering/
policing at ingress
• Support for metering/policing of incoming packets restricts incoming traffic flows to a
certain rate.
• The switches support up to six policers per Fast Ethernet port, and 60 policers on a Gigabit
Ethernet port.
• The switches offer granularity of traffic flows at 1 Mbps on Fast Ethernet ports, and 8 Mbps
on Gigabit Ethernet ports.
QoS marking at
ingress
• The switches support marking and remarking packets based on the state of policers/
meters.
• The switches support marking and remarking based on the following mappings: from
DSCP to 802.1p, and from 802.1p to DSCP.
• The switches support 14 well-known and widely used DSCP values.
• The switches support classifying or reclassifying packets based on the default DSCP per
port, and support classification based on DSCP values in the ACL.
• The switches support classifying or reclassifying frames based on the default 802.1p value
per port.
• The switches support 802.1p override at ingress.
QoS scheduling
support at egress
• Four queues per egress port are supported in hardware.
• The WRR queuing algorithm ensures that low-priority queues are not starved.
• Strict Priority Scheduling ensures that time-sensitive applications such as voice always
follow an expedited path through the switch fabric.
Sophisticated traffic
management
• The switch offers the ability to limit data flows based on MAC source or destination
address, IP source or destination address, TCP/UDP port numbers, or any combination of
these fields.
• The switch offers the ability to manage data flows asynchronously upstream and
downstream from the end station or on the uplink.
Management
Table 1 Product Features and Benefits
Feature Benefit
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(97 pages)
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