Jumbo Frames not in effect on Nexus 5548

[mmedwid]

According to this Cisco URL jumbo frames should be put into play by changing default ethernet system class. 

Recommended configuration:

!--- You can enable the Jumbo MTU 
!--- for the whole switch by setting the MTU 
!--- to its maximum size (9216 bytes) in 
!--- the policy map for the default 
!--- Ethernet system class (class-default).switch(config)#policy-map type network-qos jumboswitch(config-pmap-nq)#class type network-qos class-defaultswitch(config-pmap-c-nq)#mtu 9216switch(config-pmap-c-nq)#exitswitch(config-pmap-nq)#exitswitch(config)#system qosswitch(config-sys-qos)#service-policy type network-qos jumbo

URL:

http://www.cisco.com/en/US/products/ps9670/products_configuration_example09186a0080b44116.shtml

My configuration:

policy-map type network-qos jumbo

  class type network-qos class-default

    mtu 9216

    multicast-optimize

system qos

  service-policy type network-qos jumbo

One of my 10Gig interfaces showing only a 1500 MTU

Ethernet1/3 is up

  Hardware: 1000/10000 Ethernet, address: 547f.ee5c.69ca (bia 547f.ee5c.69ca)

  Description: Netapp FilerA e3a

  MTU 1500 bytes, BW 10000000 Kbit, DLY 10 usec

  reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA

  Port mode is access

  full-duplex, 10 Gb/s, media type is 10G

[Oleksandr Nesterov]

Hi

Here is a link for video how to configure Jumbo frames:

https://supportforums.cisco.com/videos/1215

Also check "sh queuing interface eth 1/3"

there you will be able to see real mtu, since in some nx-os releases has a cosmetic issue in displaying correct mtu.

HTH,

Alex

[vmiller]

Something else to look for:

sh interface ether1/3

Ethernet1/3 is down (SFP not inserted)

  Hardware: 1000/10000 Ethernet, address: 000d.ecec.c9ca (bia 000d.ecec.c9ca)

  Description: ovhesx01_clstr01

  MTU 1500 bytes, BW 10000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA

  Port mode is trunk

  auto-duplex, 10 Gb/s

  Beacon is turned off

  Input flow-control is off, output flow-control is off

  Switchport monitor is off

  Last link flapped never

  Last clearing of "show interface" counters never

  1 minute input rate 0 bits/sec, 0 packets/sec

  1 minute output rate 0 bits/sec, 0 packets/sec

  Rx

    0 input packets 0 unicast packets 0 multicast packets

    0 broadcast packets 0 jumbo packets 0 storm suppression packets

    0 bytes

  Tx

    0 output packets 0 multicast packets

    0 broadcast packets 0 jumbo packets

    0 bytes

    0 input error 0 short frame 0 watchdog

    0 no buffer 0 runt 0 CRC 0 ecc

    0 overrun  0 underrun 0 ignored 0 bad etype drop

    0 bad proto drop 0 if down drop 0 input with dribble

    0 input discard

    0 output error 0 collision 0 deferred

    0 late collision 0 lost carrier 0 no carrier

    0 babble

    0 Rx pause 0 Tx pause

  0 interface resets

look for the jumbo frame counter.