Configuring Qos - Cisco 3845 - Security Bundle Router Software Manual
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Configuring QoS
This chapter describes how to configure quality of service (QoS) on the ME 3800X and ME 3600X
switches by using the modular QoS command-line interface (MQC) commands. With QoS, you can
provide preferential treatment to certain types of traffic at the expense of other types. When you do not
configure QoS, the switch offers best-effort service to each packet, regardless of the packet contents or
size. MQC provides a hierarchical configuration framework for prioritizing or limiting specific streams
of traffic.
QoS includes traffic classification, marking, policing, queuing, and scheduling, configured with service
policies that are attached to ingress and egress targets. On the ME 3800X and ME 3600X switches,
targets can be switchports or Ethernet Flow Points (EFPs), also referred to as service instances. The
switches do not support service policies attached to EtherChannel port channels, although you can attach
them to ports that belong to an EtherChannel. The switches also do not support service policies attached
to the physical interface on which the EFP service instances are configured.
Ingress QoS includes classification, marking, and policing. Classification can be based on the class of
service (CoS), Differentiated Services Code Point (DSCP), IP precedence, or the multiprotocol label
switching (MPLS) experimental (EXP) value in the inbound packet. You can classify based on Layer 2
MAC, IP-standard, or IP-extended access control lists (ACLs).
Egress QoS supports the same classifications as ingress QoS except for ACLs, and also includes
classification based on QoS group or discard class. Egress QoS also includes queueing based on the
weighted tail drop (WTD) algorithm, scheduling based on shaped weights, and an egress priority queue.
You can also use hierarchical QoS to classify, police, mark, queue, and schedule inbound or outbound
traffic. You can define a policy map for the first, second, or third level of the hierarchy. Hierarchical QoS
offers classification based on the CoS, DSCP, IP precedence, or the MPLS EXP bits in the packet, and
classifying a packet based on its VLAN. The switch supports two-rate, three-color policing at different
levels. Drop policy actions include passing the packet through without modification; marking down the
CoS, DSCP, IP precedence, or the MPLS EXP bits in the packet; or dropping the packet.
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Understanding QoS, page 27-2
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Configuring QoS, page 27-24
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Displaying QoS Information, page 27-57
For more information about Cisco IOS MQC commands, see the "Cisco IOS Quality of Service
Solutions Command Reference:"
http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_book.html
For complete syntax and usage information for the platform-specific commands used in this chapter, see
the command reference for this release.
OL-23400-01
C H A P T E R
Cisco ME 3800X and 3600X Switch Software Configuration Guide
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