Re: IP Fragmentation

[Fernando Gont <fernando () gont com ar>]

At 07:07 p.m. 20/08/2008, Sam Stickland wrote:

> > Yet all OSes have it enabled and there is no fallback to 
> > fragmentation in PMTUD: if your system doesn't get the ICMP 
> > messages, your session is dead in the water.
> Windows Vista/2007 has black hole detection enabled by default. It's 
> not massively elegant, but it will keep sessions up (falls back to 
> 536 byte MTU).
>
> http://support.microsoft.com/kb/925280

IPv4 minimum MTU is 68 bytes, not 536. 536 is the minimum fragment 
re-assembly buffer size. Falling back to 536-byte packets does not 
guarantee that sessions will be kept up.

Kind regards,

--
Fernando Gont
e-mail: fernando () gont com ar || fgont () acm org
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