# IPv6 ping fails with size > 45 bytes



## santoshrps (Aug 17, 2012)

Hi,

Greetings. I am new to the FreeBSD and seek your help in resolving a IPv6 ping issue.

I am using an embedded device (access point) and i386 PC with FreeBSD. Both are connected back-to-back using a cross cable. I am able to do IPv6 ping from PC to access point. But from access point to PC, I am not able to ping if packet size is more than 45 bytes. Only one ping succeeds and FreeBSD PC continuously receives IPv6 ping packets and never responds. For ping sizes less than 45 bytes, everything is fine and I am able to do IPv6 ping from PC to access point.

I tried increasing the sysctl parameters, but couldn't get the IPv6 ping successfully.

Thanks in advance.

Regards,
Pavan


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## OH (Aug 17, 2012)

Could you elaborate more on the commands you've been using and why you're pinging with a non-standard packetsize?

Does any of the interfaces on the machines involved have a really low mtu?


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## santoshrps (Aug 18, 2012)

Thanks for the response.
I am using the ping6 command with -s (size) option with variable sizes. We are testing our access point for IPv6 conformance (IPv6 Gold), which needs the ICMP packets exchange with variable sizes. 

I verified the MTU sizes on both the machine and found as 1500.


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