Verifying Jumbo frame statistics in N5K

[e-chuah]

Hi I am running  4.2(1)N2(1a) on my N5K. I have a N5K connectd to N2K. PC connected to the N2K doing large packet ping. WHen i do a "show interface eth101/1/1" where the PC is connected. I can't see the jumbo frame statistics. WHen i do a "show interface eth1/1" (ports where N5K is connected to N2K), i can see jumbo frame statistics. Attached is the output. Just want to confirm if this is the correct behaviour. THanks Eng Wee

[CARL LINDAHL]

Is the ping successful with a 9000 byte packet?

If you look the ports on the N5K with the FEX connected by issuing " sh queuing inter eth 1/1" or whatever interface your FEX is connected to you should see the actual harware MTU instead of the visual defect on the show interface command. I agree that this bug is REALLY annoying to work with.

sh queuing inter eth 1/1

Ethernet1/1 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

on the indivduidal fex port I have no idea as I don't have any hosts running jumbo MTU on the 1gig interfaces, but agree I don't see any easy way to see if the jumo counters are not incrementing.

[Lucien Avramov]

look at : https://supportforums.cisco.com/videos/1215, I explain how to check MTU and the defect you mention on the show int.

Note that the ping with 9000 will not work if you ping from N5K. You need to make a ping test from an end host to another host and set the df bit for your ping.

[sbhadrav@cisco.com]

All you need to do is put this configuration on all your nexus 5ks:

switch(config)#policy-map type network-qos jumbo

switch(config-pmap-nq)#class type network-qos class-default

switch(config-pmap-c-nq)#mtu 9216

switch(config-pmap-c-nq)#exit

switch(config-pmap-nq)#exit

switch(config)#system qos

switch(config-sys-qos)#service-policy type network-qos jumbo

This will globally enable jumbo frame capability.

To verify that it works, do a "show int eth x/y", if you see the jumbo configuration increasing and the packets aren't getting stomped, its working.

Also note that the mtu won't change on the interface itself, its a global command, not a 'per interface' command. But thats ok, even if mtu says 1500 it can still accept jumbo frames if you have the global config applied.

Example:

Ethernet1/1 is up

...

  RX

      0 unicast packets  1221713 multicast packets  2644 broadcast packets

      1224357 input packets  91236171 bytes

---> 458 jumbo packets  0 storm suppression packets

      0 giants  0 input error  0 short frame  0 overrun   0 underrun

      0 watchdog  0 if down drop

      0 input with dribble  0 input discard

      0 Rx pause