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kridsana's avatar
kridsana
Icon for Cirrocumulus rankCirrocumulus
Dec 26, 2012

How to clear Don't Fragment (DF) bit

there is some virtual server that have a problem that     packet segment lost when MTU = 1500     so i want to clear DF bit to fix this problem , and how to clear it?     than...
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What_Lies_Bene1's avatar
What_Lies_Bene1
Icon for Cirrostratus rankCirrostratus
Jan 18, 2013
OK, so to clarify, you see the correct ICMP Fragmentation Needed message come from the firewall and it contains a lower MTU value but the F5 continues to send larger packets? I'm sure Nitass has asked before but have you also run the show net cmetric command to confirm what MTU is shown there after you see the ICMP Fragmentation Needed message.

 

 

Even if it's not updated there, do you see the F5 continue to send packets larger than the lower MTU to the firewall or not?

 

 

I doubt your ping tests are really a valid way of testing this. Can you not use a client/browser on the other side of the firewall and request some content that should result in packets that are 1500 bytes?