TCAM region sizes have
the following configuration guidelines and limitations:
show commands with the
keyword are not supported.
carving, you must save the configuration and reload the switch.
Cisco Nexus 9200 Series switches and Cisco Nexus 9300-EX Series switches are of the same type and therefore, they have the same TCAM regions.
By default, all
IPv6 TCAMs are disabled (the TCAM size is set to 0).
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 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
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.
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
Services Code Point (DSCP) based classification
service (CoS) based classification
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.
On Cisco Nexus
9200 Series switches, the ing-sup region occupies a minimum size of 512
entries, and the egr-sup region occupies a minimum size of 256 entries. These
regions cannot be configured to lesser values. Any region size can be carved
with a value only in multiples of 256 entries (with the exception of the span
region, which can be carved only in multiples of 512 entries).