I am trying to determin if Jumbo frames are enabled on out Nexus 7000, and I am getting mixed info back from the swtich.
I looks like the system jumbo MTU size is 9216 by default, but the interfaces all say the MTU of the interface is 1500 bytes. According to this article, the interface MTU should read 9216 is the jumbo frames are enabled globally. Is this correct. Is there a way to verify if Jumbo frame support is turned on?
Here is our output from sh run all | sec system
n7k1# sh run all | sec system
no system default switchport
system default switchport shutdown
system jumbomtu 9216
cdp format device-id system-name
And the interface output:
n7k1# sh int po40
port-channel40 is up
vPC Status: vPC number: 40
Hardware: Port-Channel, address: 0024.f71d.9813 (bia 0024.f71d.9813)
Description: to msndc-intel-asw Access Switches
MTU 1500 bytes, BW 20000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Port mode is trunk
full-duplex, 10 Gb/s
Input flow-control is off, output flow-control is off
Switchport monitor is off
Members in this channel: Eth1/12, Eth2/12
Last clearing of "show interface" counters never
30 seconds input rate 27816480 bits/sec, 5672 packets/sec
30 seconds output rate 33896296 bits/sec, 12904 packets/sec
Load-Interval #2: 5 minute (300 seconds)
input rate 82.15 Mbps, 9.90 Kpps; output rate 37.58 Mbps, 17.28 Kpps
57135287297 unicast packets 13338525 multicast packets 2206711 broadcast packets
57150832533 input packets 69901179046421 bytes
0 jumbo packets 0 storm suppression packets
0 runts 0 giants 0 CRC 0 no buffer
0 input error 0 short frame 0 overrun 0 underrun 0 ignored
0 watchdog 0 bad etype drop 0 bad proto drop 0 if down drop
0 input with dribble 0 input discard
0 Rx pause
100563243159 unicast packets 661949296 multicast packets 4071877704 broadcast packets
105297070159 output packets 27468942487440 bytes
0 jumbo packets
0 output error 0 collision 0 deferred 0 late collision
0 lost carrier 0 no carrier 0 babble
0 Tx pause
2 interface resets
After you turn jumbo frames on globally, you then have to set mtu under the interfaces.
There is a clear example of this in the command lookup for NX OS. Just search for jumbo frames:
switch# config t
I Wil do the same configuration tomorrow. The moment that I execute this, It´s going to result in loss of service?
Try to use
"sh queuing interface eth x/y"
since in "show interface eth x/y" correct MTU may not be visible due to cosbetic issue.