Qos Policies On Fabric Extenders - Cisco Nexus 7000 Series Configuration Manual

QoS Policies on Fabric Extenders

By default, the device always enables a system default queuing policy, or system-defined queuing policy map,
on each port and port channel. When you configure a queuing policy and apply the new queuing policy to
specified interfaces, the new queuing policy replaces the default queuing policy and those rules now apply.
The default settings for various interface modes is shown in the table below.
Trust DSCP/CoS by Default
SVI
Routed Interface
Layer 2 Interface
1
Note
When traffic is routed, the DSCP value is used (by default) to derive the egress queue. If the egress interface
is the trunk, the CoS is derived from the DSCP value of the routed packet.
For more information on the system-defined, default queuing policies and the default values that apply to
each interface, see "Using Modular QoS CLI."
The device enables other QoS features, policing and marking, only when you apply a policy map to an interface.
QoS Policies on Fabric Extenders
The Cisco Nexus 2000 Series Fabric Extender (FEX) is a remote line card that you can connect to the Cisco
Nexus 7000 Series switch. The FEX has 48 1-Gbps front-panel or server-facing ports, which are satellite
ports. The FEX has four uplink ports that you can use to connect it to the Cisco Nexus 7000 Series switch.
The four ports on the Cisco Nexus 7000 Series switch that connect to the uplink ports are fabric ports. Only
QoS policies can be configured on the server-facing FEX ports. Currently, queuing on the FEX interfaces is
not supported.
Starting with Cisco Nexus OS Release 6.2.(2), the configured MTU for the FEX ports is controlled by the
network QoS policy. To change the MTU configured on the FEX ports, you must modify the network QoS
policy to change when the fabric port MTU is also changed.
For more information on FEX, see the Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide,
Release 6.x, Cisco Nexus 7000 Series NX-OS Fundamentals Configuration Guide, Release 6.x, and Cisco
Nexus 7000 Series NX-OS Fundamentals Command Reference.
Cisco Nexus 7000 Series NX-OS Quality of Service Configuration Guide
8
When the Layer 2 Interface is an access port, it is considered as no CoS. CoS is set to 0 in the case when
access to the trunk interface with bridged traffic, even if DSCP bits are set.
Ingress
CoS
DSCP
1
CoS
Overview
Egress (After Traffic is Routed)
DSCP
DSCP
DSCP