Cisco 3850 MTU

[Diana Karolina Rojas]

Good morning community!

We are trying to connect an storage to a Cisco 3850X Switch with a TenGiga x4 module, we configured the "system mtu 9198" globally but the Jumbo frames do not cross the switch, when I try it using the Giga Interfaces it works perfectly, is there something I can do so that this work in TenGiga interfaces?

TenGigabitEthernet2/1/3 is up, line protocol is up (connected)
Hardware is Ten Gigabit Ethernet, address is 00eb.d56a.e2b7 (bia 00eb.d56a.e2b7)
MTU 9198 bytes, BW 10000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 10Gb/s, link type is auto, media type is SFP-10GBase-SR
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
30909 packets input, 3026648 bytes, 0 no buffer
Received 2916 broadcasts (2844 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 2844 multicast, 0 pause input
0 input packets with dribble condition detected
73528 packets output, 6289079 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

Thank you, 

[marce1000]

 - What do you mean by 'do not cross the switch' ?

M.

[Diana Karolina Rojas]

It does not pass through* the Switch sorry, the Jumbo packet does not arrive to the other equiptment.

Regards,

[marce1000]

 - 1) You said it worked on the Giga interface, but did you then try jumbo-framing too ?. 2) Does the end device support receiving jumbo frames  3) Is there anything to see on show logging on the switch when things do not work ?

M.

[Diana Karolina Rojas]

Marce answers to your questions:

1. The MTU configuration is globally , and is a layer 2 connection, we don't have routers or SVIs.

2. Yes, are the same hosts I am using when do the test with the TenGiga interface.

3. No, we don't have any logs.

Regards,

[marce1000]

 - Ok, their are 2 hosts; one is the storage device , and there's another; what type of device is that ? Either way , on jumbo-framing comm attempts, check their networking and or system logs (this time of both devices).Watchout for  problem info , if any.

M.

[Yachay]

Did you reboot the switch?

[Philip D'Ath]

The "system mtu" command only takes affect after a reboot.  Did you do the reboot?

[mmccrack3n]

Is a reboot required on all IOS-XE versions? TAC said it was not required, so curious what your reference is.