"ping" with packets larger then 25152 bytes fails.

Peter Jeremy peterjeremy at optushome.com.au
Wed Jul 16 21:35:31 UTC 2008

On 2008-Jul-16 12:37:59 -0700, Barney Cordoba <barney_cordoba at yahoo.com> wrote:
>> >When I run "ping" between 2 identical FreeBSD hosts, with packets larger
>> >then 25152 bytes, "ping" fails.
>Isn't this sort of like going to your auto dealer and complaining that you get vibration at 240mph?

I don't think so.  There are no specific limits on the size of ICMP
ECHO REQUEST or ICMP ECHO REPLY packets, therefore the only limit should
be the IP packet limit (64KB).  It does work with other IP stacks and
with the loopback interface on FreeBSD.

Poking around a bit more, the culprit looks like
net.inet.ip.maxfragsperpacket - which is set to 16 by default.

Peter Jeremy
Please excuse any delays as the result of my ISP's inability to implement
an MTA that is either RFC2821-compliant or matches their claimed behaviour.
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