[AusNOG] MTU debugging? (Or possibly just a fault with Amazon SES?)

[Mark Andrews]

In message <CAMmROTJqXxB7vmN8Y=Uj=HVUr9hq7_L+YqAWFd9DwP5+vXUNRw at mail.gmail.com>, Paul Wilkins writes:
>
> My understanding is well behaved hosts will send DF traffic only for
> PMTUD. If you're sending regular traffic with DF, you're pretty much
> asking for it.
>
> Paul Wilkins

For IPv4 PMTUD is basically only TCP with the exception of a couple
of platforms which basically don't follow the relevent RFC by setting
DF unconditionally.

For IPv6 PMUTD basically can't be turned off.  Instead you use
IPV6_USE_MIN_MTU and send minimal sized packets if you don't
want to do PMUTD.

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org