Cisco Nexus 5000 Series Switch CLI Software Configuration Guide, NX-OS 4.0(1a)N1 (OL-16597-01, January 2009)

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31-12
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
OL-16597-01
Chapter 31 Configuring QoS
Configuring System Classes
switch(config-pmap-c)# pause no-drop
switch(config-pmap-c)# mtu 2000
switch(config)# system qos
switch(config-system)# service-policy system-policy
In this example, the first class-map command defines a new Ethernet system class. Packets from all over
the system with 802.1p CoS value of 5 will be classified into this new system class.
The second class-map command changes the match value of the default no-drop system class.
The policy-map command defines a QoS policy for each traffic class. The new Ethernet class is
configured as a no-drop class, with an MTU of 2000 bytes. The pause no-drop command causes PFC
to apply pause functionality for packets with IEEE 802.1p priority value 5.
The service-policy command sets the specified policy as the system class.
Enabling Jumbo MTU
To enable jumbo MTU for the whole switch, set the MTU to its maximum size (9216 bytes) in the policy
map for the default Ethernet system class (class-default).
In the following example, the default Ethernet system class is configured to support the jumbo MTU:
switch(config)# policy-map jumbo
switch(config-pmap)# class class-default
switch(config-pmap-c)# mtu 9216
switch(config)# system qos
switch(config-system)# service-policy jumbo
Note The system jumbomtu command defines the maximum MTU size for the switch. However, jumbo MTU
is only supported for system classes that have mtu configured.
Verifying Jumbo MTU
To verify that jumbo MTU is enabled, enter the show interface ethernet slot/port command for an
Ethernet interface that carries traffic with jumbo MTU.
The following example shows how to display summary jumbo MTU information for Ethernet 2/1 (the
relevant part of the output is shown in bold font):
switch# show interface ethernet 2/1
Ethernet2/1 is up
...
Rx
1547805598 Input Packets 1547805596 Unicast Packets 0 Multicast Packets
0 Broadcast Packets 1301767362 Jumbo Packets 33690 Storm Suppression Packets
7181776513802 Bytes
Tx
1186564478 Output Packets 7060 Multicast Packets
0 Broadcast Packets 997813205 Jumbo Packets
4813632103603 Bytes
...
The following example shows how to display detailed jumbo MTU information for Ethernet 2/1 (the
relevant part of the output is shown in bold font):