Jumbo frames being dropped on M5300

[icotera]

I enabled jumbo frames on the switch by issuing mtu 9216 command on all of the interfaces. Connectivity works - two connected hosts ping each other - unless I increase the packet size over the standard MTU size (-s 1472 -M do is the highest size that is not being dropped). I can also see on show interface ethernet that the Discarded Rx counter increases on the interfaces. What could be the issue?

[Retired_Member]

Hi @icotera,

Welcome to the community!

As the MTU config include L2 MTU and L3 MTU concept, not sure what's your config on the port. So could you please share your detailed config?

It's better if you can provide the tech-support file of the Switch:
How do I send tech-support files from my Managed Switch to NETGEAR community moderators?
http://kb.netgear.com/app/answers/detail/a_id/31439

Another question: Does the two host IP is in same subnet?

Hope it helps!

Regards,

EricZ
NETGEAR employee

[icotera]

Thank you very much for your response.

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As the MTU config include L2 MTU and L3 MTU concept, not sure what's your config on the port. So could you please share your detailed config?

---

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I tried both:

interface 1/0/6
set igmp
mtu 9216
switchport mode trunk
switchport trunk native vlan 10
switchport trunk allowed vlan 10
vlan pvid 10
ip mtu 9000

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It's better if you can provide the tech-support file of the Switch:

I guess it will contain a lot of sensitive info, so I very much would like to avoid this.

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Another question: Does the two host IP is in same subnet?

Yes.

[Retired_Member]

Hi @icotera,

Could you please show the packet statistics of the port? Just follow below steps (keep two host ping each other with jumbo frame):

clear counters all

(wait about 1 minute)

show interface counters

show interface 1/0/6

show interface ethernet 1/0/6

[icotera]

show interface counters

https://pastebin.com/7CjkH3DS

[icotera]

show interface

https://pastebin.com/sSgEZ7fH

show interface ethernet

https://pastebin.com/VfspEwwS

[Retired_Member]

Hi @icotera,

Thanks for your immediately response. I notice there is some 'Unacceptable Frame Type' pasket statistics on the ethernet port.

1. So could you please introduce your network topo?

2. Does the two host connect to the switch directly?

3. Does the two host in same VLAN?

4. And please share the command for jumbo frame ping on your host. 

5. Could you please try to ping switch IP address with jumbo frame?

1. Total Received Packets Not Forwarded........... 66
2. 802.3x Pause Frames Received................... 0
3. Unacceptable Frame Type........................ 66

[icotera]

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Thanks for your immediately response. I notice there is some 'Unacceptable Frame Type' pasket statistics on the ethernet port.

Yup, I saw those too.

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1. So could you please introduce your network topo?

2. Does the two host connect to the switch directly?

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Yes, so there isn't really any topology to introduce.

3. Does the two host in same VLAN?

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Yes.

4. And please share the command for jumbo frame ping on your host.

Windows: ping IP -t -l 1700 -f

Linux: ping IP -s 1700 -M do

5. Could you please try to ping switch IP address with jumbo frame?

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This works, I'm getting echo replies.

[Retired_Member]

Hi @icotera,

I test in my side with M5300 switch. It's work success when two hosts ping each other with jumbo frame.

It's very stange.

What's firmware of your switch? Please make sure set MTU value to maximum on two ports that connect the host.

And could you please reload the switch and try again?

[icotera]

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I test in my side with M5300 switch. It's work success when two hosts ping each other with jumbo frame.

It's very stange.

What's firmware of your switch?

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11.0.0.31

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Please make sure set MTU value to maximum on two ports that connect the host.

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The MTU on all ports on the switch is 9216

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And could you please reload the switch and try again?

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Unfortunately, it didn't help.