Jumbo packet ping from PC (windows 10)

Referring to this link How to test if 9000 MTU/Jumbo Frames are working - Blah, Cloud.

I tried to follow its instruction guide to ping Jumbo packet from my PC (Windows 10).

ping -f -l 9000 192.168.1.88

However, it show the error as below:

Pinging 192.168.1.88 with 9000 bytes of data:

Packet needs to be fragmented but DF set.

How should I do to make the Jumbo Packet ping successfully?

I had enabled Jumbo packet in both PC, but it still show the same error as above.

4 Answers

Directly from Microsoft's technet page:

Error Message:

Packet needs to be fragmented but DF set.

Explanation:

The packet length is to big to be processed by the ping command.

User Action:

Turn off the Do Not Fragment flag by removing the -f option from the command line and then try again. You may try decreasing the packet size by using the -l option prior to disabling the Do Not Fragment flag.

As the page says, it means you're sending packets larger than can be handled.

For anyone stumbling upon this later on, it seems the netsh way is not persistent despite the "store=persistent" parameter.

Modifying the registry proved annoying, but Powershell does the trick:

Assuming you have interfaces named iSCSI1, iSCSI2, etc.

Get-NetAdapterAdvancedProperty "iSCSI*" -DisplayName "Jumbo*" | Set-NetAdapterAdvancedProperty -RegistryValue "9014"

Then you can verify with ping:

ping -f -l 8972 [host IP]

You've selected 4K MTU rather than 9K MTU as that tutorial was testing for. Right now, the max ping packet size you could send is 4000.

Setting the NIC properties is not enough as that will only allow you to receive Jumbo frames.

You'll also need to tell Windows to use Jumbo frames.

1) In command prompt or PowerShell, type:

netsh interface ipv4 show subinterface

Make a note of the name of the interface that you want to enable Jumbo frames on.

2) Then type:

netsh interface ipv4 set subinterface “TheNameOfYourInterface” mtu=9000 store=persistent

3) Reboot your computer