Cisco Nexus 9000 Series Configuration Manual page 57

Configuring QoS TCAM Carving
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
• By default, the TCAM region for CoPP is 95% utilized on the Nexus 9300/Nexus 9500 series switch.
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.
• When any of the following classification criteria are used for IPv4 and IPv6, you need to carve the IPv4
based QoS TCAM region. It is not necessary to carve an IPv6 based QoS TCAM region.
• When a QoS policy is applied on multiple interfaces or multiple VLANs, the label is not shared since
the statistics option is enabled.
To share the label for the same qos policy that is applied on multiple interfaces or multiple VLANs, you
need to configure the qos policy with no-stats option using the service-policy type qos input my-policy
no-stats command.
• On Cisco Nexus 9300 Series switches, the X9536PQ, X9564PX, and X9564TX line cards are used to
enforce the QoS classification policies applied on 40G ports. It has 768 TCAM entries available for
carving in 256-entry granularity. These region names are prefixed with "ns-".
• For the X9536PQ, X9564PX, and X9564TX line cards, only the IPv6 TCAM regions consume
double-wide entries. The rest of the TCAM regions consume single-wide entries.
• When a VACL region is configured, it is configured with the same size in both the ingress and egress
directions. If the region size cannot fit in either direction, the configuration is rejected.
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.
◦ Differentiated Services Code Point (DSCP) based classification
◦ Class of service (CoS) based classification
◦ IP precedence based classification
Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 7.x
Guidelines and Limitations
43