North American Network Operators Group
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Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU

  • From: Iljitsch van Beijnum
  • Date: Sun Jan 09 18:41:11 2005 
On 10-jan-05, at 0:08, Mark Andrews wrote:


	Well DNS (not EDNS) is limited to 512 octets so you unless there
	are real links (not ones artificially constrained to demonstrate
	a issue) this should not be a issue in practice.

No, fortunately not. But it's still VERY wrong and it must be fixed.


	Note for IPv6 one sets IPV6_USE_MIN_MTU on the UDP socket so this
	should be a non-issue there.
In IPv6 PMTUD is handled at the IP layer so the second packet that's too large will be fragmented at the source, so there is no issue.