Minimum Internet MTU

bill bmanning at
Mon Dec 22 13:27:13 UTC 2003

> A few years back I noted some 512-536 MTU links in ASIA. I've been doing
> some testing and can't seem to find them anymore. Is is safe to assume
> that 99.9% of the Internet is running on 1500 MTU or higher these days? 

	define safe. 

> I know some people artificially set their end point MTU a bit lower
> (like 1400) to deal with things like having their traffic encapsulated
> by GRE or IPSec. With this in mind, would we be safe to flag/drop/what
> ever all fragments smaller than 1200 bytes that are not last fragments
> (i.e., more fragments is still set)? Does anyone maintain, or is aware,
> of links that would not meet this 1200 MTU?

	now that you mention it...  :)
	btw, what will your IDS/firewall do when presented w/ a 9k mtu?

> Any and all feedback would be greatly appreciated,
> C

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