I was responding to his post that blocking or disabling PMTUD was the way to avoid the ping of death, which is False, nothing more, nothing less. As far as who Iljitsch is, everyone misspeaks from time to time. Even those of us who have been at this for nearly 3 decades.
-----Original Message----- From: Nathan Anderson/FSR [mailto:nathana@fsr.com] Sent: Wednesday, May 07, 2008 2:08 PM To: nanog@merit.edu Subject: Re: [NANOG] Microsoft.com PMTUD black hole?
Tomas L. Byrnes wrote:
The remedy you have below is NOT the only one, and is, in fact, a non-sequitur in this case.
How so? Iljitsch is suggesting that ICMP blockers originate packets without DF set if they are going to block the ICMP messages that PMTUD needs in order to work in the first place. That's what (I think) he means by "disabling path MTU discovery."
The network-level solution to ping of death is to BLOCK fragmented packets, and the way to ensure this doesn't self-deny-service is to perform PMTUD and Black-Hole Router discovery.
Which end are you talking about here, the servers or the client? If the servers, how do you expect them to do PMTUD if they _can't hear the ICMP messages_?
Also, for some reason, as I pointed out before, XP black hole router discovery doesn't seem to be working for me for whatever reason. Does anybody have any clue why that might be the case?
-- Nathan Anderson First Step Internet, LLC nathana@fsr.com
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