FCoE Cookbook for HP Virtual Connect Version 4.20 Firmware Enhancements May 2014
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Quality of Service Configuration
The default Virtual Connect configuration provides lossless service of the FCoE traffic. PFC (Priority Flow Control)
mechanisms are used to provide the FCoE lossless service and prevent congestion. It is therefore not necessary to
enable any particular QoS settings in the VC Domain.
Since Virtual Connect provides only best effort service for Ethernet traffic (i.e. flow control does not take place, in the
event of congestion, packets get dropped) Administrator can decide to configure QoS in the Virtual Connect Domain and
on the upstream switches to improve the Ethernet traffic service level control.
The bandwidth allocation for FCoE-capable SUS uplinks always allocates only half the link bandwidth to FCoE traffic,
with the other half allocated to Ethernet traffic. Since VC 4.01, this allocation is fixed and cannot be modified.
Therefore it is important to configure the upstream switches with the same Virtual Connect Domain QoS settings as
follow:
FCoE lossless traffic class 3.
50/50% of bandwidth sharing between regular and lossless traffic.
Note: Conflicting QoS parameters between the Virtual Connect Domain and the upstream environment can badly impact
the traffic and affect the performance.
QoS on Nexus 5010 and 5020
On the Nexus 5010 and 5020 it is not necessary to modify the QoS settings because by default once the FCoE feature is
configured (by entering “feature fcoe”) the default QoS template for shared links allocates the same shares and
priorities than Virtual Connect. The following two classes of service are automatically configured:
class-fcoe is configured to be no-drop with a COS priority 3 and a MTU of 2158 with an ingress/egress bandwidth
allocation of 50%.
class-default is configured to be drop with an MTU of 1500 with an ingress/egress bandwidth allocation of 50%.
To verify that the FCoE policy maps can be found in the running configuration, enter:
show policy-map system