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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 44 Configuring Quality of Service
Configuring QoS on a Standalone Supervisor Engine 6-E/6L-E or Supervisor Engine 7-E/7L-E/8-E
• A policy can contain multiple classes and each class-map may contain the same or different FNF
flow record.
• Flow based QoS policy and FNF monitor both cannot be applied on the same target at the same time.
• When the interface mode changes from switchport to routed port and vice versa, any Flow QoS
policy attached to the port remains applied after the mode change.
• There are 3 types of FNF flow records: ipv4, ipv6, and datalink. The datalink flow record is mutually
exclusive with the ipv4 and ipv6 flow records; a classmap with the datalink flow record cannot
co-exist with classmap having a ipv4 or ipv6 flow record in the same policy and vice-versa.
• Classmap class-default is not editable; it cannot be configured with the match flow record. Instead,
you can configure the policy with a class-map that uses a match any filter and the flow record.
• Traffic is classified in the same order in which class-map is defined in a policy. Hence, if a FNF flow
record is the only match statement in a class-map, the classifier matches all packets of the type
identified by the flow record. This means that any subsequent class-map in the same policy matching
on the same traffic type will be redundant and will never be hit.
• Policers associated with classmap having flow record are called microflow policers. The CIR and
PIR rates for microflow policers cannot be configured using the percent keyword.
• Flow records within the same policy must include appropriate key fields to ensure flows created
from different classmaps are unique and distinct. Otherwise, the resulting flows from different
classmap cannot be distinguished. In such cases, policy actions corresponding to the classmap which
created the first flow in hardware will apply and results will not be always be as expected.
• Flows from traffic received on different QoS targets are distinct even if the same policy is applied
to those targets.
• A flow is aged out if the it is inactive for more than 5 seconds; there is no traffic matching the flow
for a period longer than 5 sec.
• When a flow is aged out, policer state information associated with the flow is also deleted. When a
new flow is created, the policer instance for the flow is re-initialized.
• Flows created by flow based QoS policy exist in hardware only and cannot be exported (as with FNF
monitor).
• Per-flow statistics are not available for flows created by flow based QoS policy.
• Class-map statistics indicate the number of packets matching the classifier. It does not represent
individual flow stats.
• Policer statistics show the aggregate policer statistics of individual flow.
• Information about the flows created by hardware are not available and not displayed in the show
commands associated with QoS policy-map. Only class-map and policer statistics are displayed in
the output of the show policy-map commands.
Configuring CoS Mutation
CoS reflection and CoS mutation are supported on Supervisor Engine 6-E and Catalyst 4900M. Below
is an example of how to apply CoS reflection.
Let us say that traffic arrives on interface gigabit 2/5 with VLAN 10 and COS 1, 2, .... We want traffic
to egress interface gigabit 2/6 with outer tag VLAN 11 and CoS copied from C-tag, where C-tag is
VLAN 10 and COS 1, 2, ...
class-map match-all c2
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