Cisco Nexus 7000 Series Configuration Manual page 141

Configuring Queuing and Scheduling on F-Series I/O Modules
• See the following information about the Cisco 7710/7718 switches and the four default 4p8q policy
templates that support eight egress queues on these switches:
• See the following information about the match dscp command:
• Shared buffer queuing between ports in a port group is available only on the F3 Series modules.
• Shared buffering is supported only in 8e and 8e-4q4q templates.
• Break-out ports do not support shared buffering.
• The M1, M2, F1, F2 and F2e modules do not support shared buffering.
• Reloading an F2 module brings up all the cleared default 8e-4q4q template related policy-maps by
using the clear qos policies 8e-4q4q command.
• The default 8e-4q4q-policy template is published when a software upgrade is completed.
• The default 4q8q-policy templates are supported and enabled by default on the Cisco Nexus 7710
switch and Cisco Nexus 7718 switch only.
• The default 4q8q-policy templates are supported on F2e modules only.
• DSCP queuing is enabled by default on the Cisco Nexus 7710/7718 switches. You must use the no
hardware qos dscp-to-queue command to disable DSCP queuing on the switch. You can use the
hardware qos dscp-to-queue command module type command to reenable DSCP queuing.
• Supports only the ingress queues for F2 modules for the 8E template. (It does not support egress
queues, M1 queues, or fabric-qos queues.)
• Supports only ingress queues that have at least one CoS value associated with it without any restriction
on which CoS value is used.
• Cannot be used in user-defined class maps.
• Cannot be used in a user configuration session.
• Must be disabled for ISSD. (If it is not disabled, the ISSD is disruptive).
• DSCP to IVL mapping is disabled by default.
• The queue-limit command cannot be specified based on CoS or DSCP values. The configured
queue-limit sizes are applicable for both the DSCP and CoS values.
• No additional statistics are generated to differentiate how many packets are matched on DSCP or
CoS.
• When DSCP to IVL is enabled, an interface uses the DSCP value as trusted for IP packets and the
CoS value is trusted for non-IP packets.
• DSCP to IVL mapping is enabled by default on the Cisco Nexus 7710/7718 switches. You must
use the no hardware qos dscp-to-queue command to disable DSCP to IVL mapping.
• DSCP to IVL mapping for FabricPath interfaces is not supported.
• DSCP to IVL mapping for IPv6 packets is not supported.
• DSCP to IVL mapping change is a disruptive operation and might cause BFD/routing protocols to
flap.
Cisco Nexus 7000 Series NX-OS Quality of Service Configuration Guide
Guidelines and Limitations
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