Prerequisites For Queuing And Scheduling; Guidelines And Limitations - Cisco Nexus 7000 Series Configuration Manual

Configuring Queuing and Scheduling on M-Series I/O Modules

Prerequisites for Queuing and Scheduling

Queuing and scheduling have the following prerequisites:
• You must be familiar with the "Using Modular QoS CLI" chapter.
• You are logged on to the switch.
• You are in the correct VDC. A VDC is a logical representation of a set of system resources. You can use

Guidelines and Limitations

Queuing and scheduling have the following configuration guidelines and limitations:
•
• Configure system-defined class maps with care because the changes occur immediately and traffic might
• Defining the CoS with the match cos command is not supported for custom configured class maps.
• Specifying DSCP values for a class map with the match dscp command is not supported for custom
• When you are working with 10-Gigabit Ethernet ports in the shared mode, the egress queuing policy
• You cannot set either the queue limit or WRED on ingress 10-Gigabit Ethernet ports except for the 8
• To ensure accurate hardware programming on Cisco M1 Series modules, when you add a physical
• On Cisco M1 series modules, it may not be possible to configure actual values for traffic shaping. For
• When changing egress Class of Service (CoS) to queue mapping, ensure that you specify 2 or 3 seconds
• The Cisco M3 series modules do not support per-queue counters for egress drops (multicast, unknown
• Only 8e templates are supported on Cisco M3 series modules.
• In Cisco Nexus 7700 switches, the Cisco M3 series module supports only network-qos policies based
the switchto vdc command with a VDC number.
be disrupted on all VDCs.
configured class maps.
applies to all the ports in the port group. With the 10-Gigabit Ethernet ports in shared mode, all the ports
in the port group must be in the same VDC. For information about the shared and dedicated modes, see
the Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide. For information about the port
groups, see the Cisco Nexus 7000 Series Hardware Installation and Reference Guide.
port, 10-Gigabit Ethernet I/O module.
interface to a port-channel, which already has a queuing policy applied, you must remove the queuing
policy and reapply. Without this reapplication, queuing policy will not be correctly applied on all the
interfaces. Otherwise, you must ensure that the queuing policy is applied on the port-channel interface
only after all the physical ports are bundled into the port-channel.
example, on a 1 Gigabit interface with 65% average shaping, the output rate on the interface goes only
up to 450Mbps, whereas with 70%, it goes to 850Mbps.
as the minimum time limit between changes. Otherwise, continuous traffic drop might occur.
unicast, or broadcasts). The egress drops will be per port and per Q-Default counter.
on the 8e-4q8q template.
Cisco Nexus 7000 Series NX-OS Quality of Service Configuration Guide
Prerequisites for Queuing and Scheduling
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