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Cisco IE 2000 Switch Software Configuration Guide
OL-25866-01
Chapter 38 Configuring Standard QoS
Information About Standard QoS
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In a hierarchical policy map attached to an SVI, you can only c onfigure an individual policer at
the interface level on a physical port to specify the bandwidth limits for the traffic on the port.
The ingress port must be configured as a trunk or as a static-access port. You cannot configure
policers at the VLAN level of the hierarchical policy map.
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The switch does not support aggregate policers in hierarchical policy maps.
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After the hierarchical policy map is attached to an SVI, the interface-level policy map cannot
be modified or removed from the hierarchical policy map. A new interface-level policy map also
cannot be added to the hierarchical policy map. If you want these changes to occu r, the
hierarchical policy map must first be removed from the SVI. You also cannot add or remove a
class map specified in the hierarchical policy map.

Policing

• The port ASIC device, which controls more than one physical port, supports 256 policers (255
user-configurable policers plus 1 policer reserved for system internal use). The maximum number
of user-configurable policers supported per port is 63. For example, you could configure 32 polic ers
on a Gigabit Ethernet port and 8 policers on a Fast Ethernet port, or you could co nfigure 64 policers
on a Gigabit Ethernet port and 5 policers on a Fast Ethernet port. Policers are allocated on demand
by the software and are constrained by the hardware and ASIC boundaries. You cannot reserve
policers per port; there is no guarantee that a port wi ll be assigned to any policer.
• Only one policer is applied to a packet on an ingress port. Only the average rate and committed burst
parameters are configurable.
• You can create an aggregate policer that is shared by multiple traffic classes within the same
nonhierarchical policy map. However, you cannot use the aggregate policer across different policy
maps.
• On a port configured for QoS, all traffic received through the port is classified, pol iced, and marked
according to the policy map attached to the port. On a trunk port configured for QoS, traffic in all
VLANs received through the port is classified, policed, and marked according to the policy map
attached to the port.
• If you have EtherChannel ports configured on your switch, you must configure QoS classification,
policing, mapping, and queueing on the individual physical por ts that comprise the EtherChannel.
You must decide whether the QoS configuration should match on all ports in the EtherCh annel.
Default Standard QoS Configuration
QoS is disabled. There is no concept of trusted or untrusted ports because the packets are not modified
(the CoS, DSCP, and IP precedence values in the packet are not changed). Traffic is switched in
pass-through mode (packets are switched without any rewrites and classified as best effort without any
policing).
When QoS is enabled with the mls qos global configuration command and all other QoS settings are at
their defaults, traffic is classified as best effort (the DSCP and CoS value is set to 0) without any polici ng.
No policy maps are configured. The default port trust state on all ports is untrusted. The default ingress
and egress queue settings are described in the “Default Ingress Queue Settings” section on page 38-7 and
the “Default Egress Queue Settings” section on page 38-7.