Q. How can I test if two machines are using jumbo frames?

John Savill

January 10, 2010

1 Min Read
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A. An easy way to check if you're sending 9kB packets instead of the 1.5kB standard is to use the ping command. Use a data size of 8kB bytes along with the no-fragment switch.

ping  -f -l 8000

As can be seen in my example below, I can successfully use jumbo frames to talk to savdalvs02, but not to savdalwks01. If I reduce the packet size to 800B, it works just fine for non-jumbo frame hosts.

If I use the command

ping savdalvs02 -f -l 8000

I'll see

Pinging savdalvs02.savilltech.net [192.168.1.31] with 8000 bytes of data:Reply from 192.168.1.31: bytes=8000 time<1ms TTL=128Reply from 192.168.1.31: bytes=8000 time<1ms TTL=128Reply from 192.168.1.31: bytes=8000 time<1ms TTL=128Reply from 192.168.1.31: bytes=8000 time<1ms TTL=128Ping statistics for 192.168.1.31:Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),Approximate round trip times in milli-seconds:Minimum = 0ms, Maximum = 0ms, Average = 0ms

But if I enter

ping savdaldc10 -f -l 8000

I'll see

Pinging savdaldc10.savilltech.net [192.168.1.10] with 8000 bytes of data:Request timed out.Request timed out.Request timed out.Request timed out.Ping statistics for 192.168.1.10:Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

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Check out hundreds more useful Q&As like this in John Savill's FAQ for Windows. Also, watch instructional videos made by John at ITTV.net.

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