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Chapter 31
Configuring QoS
S e n d f e e d b a c k t o n x 5 0 0 0 - d o c f e e d b a c k @ c i s c o . c o m
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When configuring Ethernet port channels, note the following guidelines:
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Configuring PFC and LLC
Cisco Nexus 5000 Series switches support PFC and LLC on Ethernet interfaces. The Ethernet interface
can operate in two different modes: FCoE mode or standard Ethernet mode.
If the interface is operating in FCoE mode, the Ethernet link is connected at the server port using a
converged network adapter (CNA). Refer to
configuring PFC and LLC when the interface is operating in FCoE mode.
If the interface is operating in standard Ethernet mode, the Ethernet link is connected at the server port
with a standard Ethernet network adapter (NIC). The network adapter must support DCBX protocol for
PFC or ingress policing to be supported on the interface.
You must configure a no-drop Ethernet system class for PFC to operate on Ethernet traffic (PFC will be
Note
applied to traffic that matches the CoS value configured for this class).
Configuring PFC and LLC for standard Ethernet is covered in the following topics:
•
•
Configuring Priority Flow Control
By default, Ethernet interfaces negotiate PFC capability with the network adapter using DCBX protocol.
When PFC is enabled, PFC is applied to traffic that matches the CoS value configured for the no-drop
Ethernet class.
You can override the negotiation result by force-enabling the PFC capability. To force-enable the PFC
capability, perform this task:
Command
Step 1
switch# configure terminal
Step 2
switch(config)# interface type slot/port
Step 3
switch(config-if)# priority-flow-control
mode {auto|on}
OL-16597-01
All FCoE traffic on an Ethernet interface is mapped to one no-drop system class. By default, this
class is associated with CoS value 3, although you can configure a different value. If you configure
standard Ethernet traffic to use the same CoS value as FCoE, this traffic is still mapped to the FCoE
system class and the switch will apply priority flow control on the FCoE CoS value.
The service policy configured on a port channel applies to all member interfaces.
The priority flow control configured on a port channel applies to all member interfaces.
Configuring Priority Flow Control, page 31-7
Configuring IEEE 802.3x Link-Level Flow Control, page 31-8
Chapter 29, "Configuring FCoE"
Purpose
Enters configuration mode.
Specifies the interface to be changed.
Sets PFC mode for the selected interface.
Specify on to force-enable PFC.
Specify auto to negotiate PFC capability.
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
Configuring PFC and LLC
for information about
31-7
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