Guidelines And Limitations - Cisco Nexus 9000 Series Configuration Manual

Configuring QoS TCAM Carving

Guidelines and Limitations

TCAM region sizes have the following configuration guidelines and limitations:
• show commands with the internal keyword are not supported.
• After TCAM carving, you must save the configuration and reload the switch.
• Cisco Nexus 9200 platform switches and Cisco Nexus 9300-EX platform switches are of the same type
• By default, all IPv6 TCAMs are disabled (the TCAM size is set to 0).
• Use the show hardware access-list tcam region command to view the configured TCAM region size.
• Beginning with Cisco NX-OS Release 7.0(3)I5(2), the global CLI hardware qos classify ns-only
• By default, the TCAM region for CoPP is 95% utilized on the Nexus 9300/Nexus 9500 platform switch.
• When any of the following classification criteria are used for IPv4 and IPv6, you need to carve the IPv4
and therefore, they have the same TCAM regions.
command is introduced to enable configuration of the QoS policy on the NS ports without carving the
T2 QoS region, for example, qos and l3-qos regions. This command removes the TCAM restrictions that
are associated with the QoS classifications on the ALE ports and it is only supported on Cisco Nexus
9000 Series switches with Application Leaf Engine (ALE).
For example, for Layer 2 Application Leaf Engine (ALE) port with IPv4 traffic, qos, and ns-qos TCAM
carving is a must for the QoS classification to work. With the hardware qos classify ns-only CLI
command, ns-QoS TCAM alone is sufficient.
See the following example for applying the CLI hardware qos classify ns-only command:
switch(config)# hardware qos classify ns-only
Warning: This knob removes the restriction of carving qos as well as ns-qos TCAM region
for NS port QoS classification policies.
Warning: Only NS TCAM will be used, as a result policy-map statistics, marking and
policing is not supported on NS ports
See the following example for removing the CLI hardware qos classify ns-only command:
switch(config)# no hardware qos classify ns-only
Warning: Special knob removed. Please remove and apply QoS policies on NS ports to get
default behavior
Note Policing, policy-map statistics, and marking are not supported on the NS ports if
the hardware qos classify ns-only CLI command is used. The show policy-map
interface ethernet x/y does not return QoS statistics. The NS TCAM does not
have some of the Network Forwarding Engine (NFE) TCAM resources, for
example, range etc. Therefore, the policies may need more TCAM entries.
If you modify the CoPP policy, it is likely that you will need to modify other TCAM region sizes to allow
for more space to be applied to the CoPP TCAM region.
based QoS TCAM region. It is not necessary to carve an IPv6 based QoS TCAM region.
• Differentiated Services Code Point (DSCP) based classification
Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 7.x
Guidelines and Limitations
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