Fabric Extender provides two user queues for its
quality of service (QoS) support, one for all no-drop classes and one for all
drop classes. The classes configured on its parent switch are mapped to one of
these two queues; traffic for no-drop classes is mapped to one queue and
traffic for all drop classes is mapped to the other. Egress policies are also
restricted to these two classes.
The parent switch
provides two predefined type qos class maps for matching broadcast or multicast
traffic; class-all-flood and class-ip-multicast. These classes are ignored on
Fabric Extender uses IEEE 802.1p class of service
(CoS) values to associate traffic with the appropriate class. Per-port QoS
configuration and CoS-based egress queuing is also supported.
support pause frames, which is implemented using IEEE 802.3x link-level flow
control (LLC). By default, flow control send is on and flow control receive is
off on all host interfaces. Autonegotiation is enabled on the host interfaces.
Per-class flow control is set according to the QoS classes.
support jumbo frames (up to 9216 bytes); however a per-host interface maximum
transmission unit (MTU) is not supported. Instead, MTU is set according to the
QoS classes. You modify MTU by setting policy and class maps on the parent
switch. Because the
Fabric Extender has only two user queues, the MTU for
the drop-queue is set to the maximum MTU of all drop classes and the MTU on the
no-drop queue is set to the maximum MTU of all no-drop classes.
For more information
about LLC and quality of service, see the
Cisco Nexus 5000 Series NX-OS
Quality of Service Configuration Guide, Release 4.2(1)N1(1).