Using Metadata In Qos Policy - Cisco Catalyst 4500 series Administration Manual

Chapter 42 Configuring Quality of Service

Using Metadata in QoS Policy

Beginning with Cisco IOS Release IOS XE 3.3.0SG and IOS 15.1(1)SG, you can configure class-map
with metadata filters. A QoS policy that include such classes is termed a metadata based QoS policy or
parameterized QoS policy. It allows you to classify flows based on intuitive and user friendly metadata
attributes rather than individual flow 5-tuple and applicable QoS actions.
Software uses mechanisms like MSI and MSI-Proxy to do the following:
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For configuration details on Cisco Medianet Metadata, refer to the following URLs:
http://www.cisco.com/en/US/docs/ios-xml/ios/mdata/configuration/15-mt/metadata-framework.htmll
For details on the metadata commands, refer to the following URL:
http://www.cisco.com/en/US/docs/ios-xml/ios/qos/command/qos-cr-book.html
For configuration details on Cisco Media Services Proxy, refer to the following URL:
http://www.cisco.com/en/US/docs/ios-xml/ios/msp/configuration/15-mt/media-ser-prxy.html
For command details on Cisco Media Services Proxy, refer to the following URL:
http://www.cisco.com/en/US/docs/ios-xml/ios/msp/command/reference/guide/media-ser-prxy.html
Restrictions
The following restrictions apply to using a metadata-based QoS policy on a Catalyst 4500 series switch:
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Observing Metadata Filter Statistics
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OL_28731-01
Identify flows
Glean metadata information from the traffic received at the network edge
Generate and transport metadata information using RSVP messages hop-by-hop to every network
element along the flow path using on-path RSVP signalling mechanism.
They can only be attached to target in input direction.
They can only be attached to physical ports and EtherChannel. They cannot be attached to VLANs,
port VLANs, and SVI interfaces.
A policy can have multiple metadata-based classifiers.
A class-map can have one or more metadata filters with match-any or match-all semantics.
Policy actions corresponding to metadata class are applied on aggregate traffic. However, if the
metadata filter is configured along with Flexible NetFlow record filter, the policy action (like
policer) applies on individual flows.
If there are no flows associated with metadata filter, the software configures an implicit ACL with
a deny ACE.
If the same metadata QoS policy is applied on multiple interfaces, the policy is installed in hardware
in separate TCAM entries for each interface; the TCAM entries are not shared by the interfaces.
When a new flow is associated with a metadata filter, the software installs a new set of TCAM entries
that includes the new flow along with other existing previously-discovered flows.
Although interfaces with the same metadata policy do not share TCAM resources in hardware, the
metadata filter statistics observed with the show policy-map interface ifname command are reported
as though it were shared.
Only metadata filter statistics are available. The individual flow statistics are not available.
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
Overview of QoS
42-11