Re: [NANOG] Microsoft.com PMTUD black hole?

[Nathan Anderson/FSR <nathana () fsr com>]

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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