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Cisco IE 3010 Switch Software Configuration Guide
OL-23145-01
Chapter 33 Configuring QoS
Configuring Standard QoS
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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 Guidelines
These are the policing guidelines:
• 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 bo undaries. You cannot reserve
policers per port; there is no guarantee that a port w ill 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 EtherChannel .
General QoS Guidelines
These are general QoS guidelines:
• Control traffic (such as spanning-tree bridge protocol data units [BPDUs] and routing update
packets) received by the switch are subject to all ingress QoS processing.
• You are likely to lose data when you change queue settings; therefore, try to make change s when
traffic is at a minimum.