Qos Treatment For Performance-Monitoring Protocols; Cisco Ip-Slas Probes; Cpu Traffic - Cisco 3845 - Security Bundle Router Software Manual

Chapter 27 Configuring QoS
However, these output policy maps can contain only three unique configurations of queue limits. These
three unique queue-limit configurations can be included in as many output policy maps as there are
switch ports. There are no limitations on the configurations of bandwidth, priority, or shaping.

QoS Treatment for Performance-Monitoring Protocols

QoS is not configurable for Cisco IP service level agreements (IP SLA) probes or for traffic to the CPU.
QoS treatment is set by default.
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Cisco IP-SLAs Probes

For information about Cisco IP service level agreements (IP SLAs), see the
IP SLAs" section on page
The QoS treatment for IP-SLA probes exactly reflects effects that occur to the normal data traffic
crossing the device. The generating device does not change the probe markings. It queues these probes
based on the configured queueing policies for normal traffic.
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CPU Traffic

By default, the switch assigns a separate classifier, CPU-traffic classifier, for all traffic destined to the
CPU. For traffic from the CPU, the switch uses a default classifier for high-priority control protocol
traffic. These protocols are considered high priority:
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All other traffic from the CPU is classified with a normal classifier.
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Cisco IP-SLAs Probes, page 27-23
CPU Traffic, page 27-23
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Marking
By default, the CoS marking of CFM traffic (including IP SLAs using CFM probes) is not changed.
QoS configuration cannot change this behavior.
By default, IP traffic marking and the CoS marking of all other Layer 2 non-IP traffic is not changed.
The QoS marking feature can change this behavior.
Queuing
IP SLAs traffic is queued according to its ToS or DSCP value and the output policy map configured
on the egress target, similarly to normal traffic. QoS cannot change this behavior.
By default, all other Layer 2 non-IP traffic and all IP traffic is statically mapped to a queue on the
egress target.
Protocols with the PAK_PRIORITY flag set in Cisco IOS software. These include EIGHT, HSPR,
GRD, LDP, OSPF, RIP, WCCP, BFD, CFM, SAA, CDP, ISIS, DTP, IGRP, Ethernet OAM, LACP,
LLDP, PAgP, and STP.
IP protocols with IP precedence set to 6 or 7.
Cisco ME 3800X and 3600X Switch Software Configuration Guide
Understanding QoS
"Understanding Cisco IOS
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