Verifying the Jumbo MTU
On the Cisco Nexus device, traffic is classified into one of eight QoS groups. The MTU is configured at the
QoS group level. By default, all Ethernet traffic is in QoS group 0. To verify the jumbo MTU for Ethernet
traffic, use the
show queueing interface ethernet slot/chassis_number
command and find "HW MTU" in
the command output to check the MTU for QoS group 0. The value should be 9216.
The
show interface
command always displays 1500 as the MTU. Because the Cisco Nexus device supports
different MTUs for different QoS groups, it is not possible to represent the MTU as one value on a per interface
level.
For Layer 3 routing on the Cisco Nexus device, you must verify the MTU on the Layer 3 interfaces (SVIs
and physical interfaces with IP addresses) in addition to the global QoS MTU. You can verify the Layer
3 MTU by using the
show interface vlan vlan_number
or
show interface slot/chassis_number
.
Note
This example shows how to display jumbo MTU information for Ethernet 1/19:
switch#
show queuing interface ethernet1/19
Ethernet1/19 queuing information:
TX Queuing
qos-group
sched-type
oper-bandwidth
0
WRR
50
1
WRR
50
RX Queuing
qos-group 0
q-size: 243200,
HW MTU
: 9280 (
9216
configured)
drop-type: drop, xon: 0, xoff: 1520
Statistics:
Pkts received over the port
: 2119963420
Ucast pkts sent to the cross-bar
: 2115648336
Mcast pkts sent to the cross-bar
: 4315084
Ucast pkts received from the cross-bar
: 2592447431
Pkts sent to the port
: 2672878113
Pkts discarded on ingress
: 0
Per-priority-pause status
: Rx (Inactive), Tx (Inactive)
qos-group 1
q-size: 76800, HW MTU: 2240 (2158 configured)
drop-type: no-drop, xon: 128, xoff: 240
Statistics:
Pkts received over the port
: 0
Ucast pkts sent to the cross-bar
: 0
Mcast pkts sent to the cross-bar
: 0
Ucast pkts received from the cross-bar
: 0
Pkts sent to the port
: 0
Pkts discarded on ingress
: 0
Per-priority-pause status
: Rx (Inactive), Tx (Inactive)
Total Multicast crossbar statistics:
Mcast pkts received from the cross-bar
: 80430744
Verifying the System QoS Configuration
Use one of the following commands to verify the configuration:
Cisco Nexus 5000 NX-OS Quality of Service Configuration Guide, Release 5.1(3)N2(1)
OL-26657-01
41
Configuring QoS on the System
Verifying the Jumbo MTU