Masataka, On 6/15/2012 3:48 AM, Masataka Ohta wrote: > After thinking more about the draft, I think it is > purposelessly hostile against innocent operators and > end users who are suffering between people filtering > ICMP and people insisting on PMTUD. > > Today, innocent operators often clear DF bit and > end users are happy with it, because, today, probability > of accidental ID match is small enough. That is not an innocent action. It defeats PMTUD, which is a draft standard. It also violates RFC 791 and 1121. > However, as the ID specifies: > > >> Originating sources MAY set the IPv4 ID field of atomic datagrams > to any value. > > >> IPv4 datagram transit devices MUST NOT clear the DF bit. > > people insisting on PMTUD are now authorized to set ID always > zero, trying to discourage ICMP filtering and DF bit clearing. > > But, as people filtering ICMP won't stop doing so and if > operators can do nothing other than clearing DF, it is > end users who suffers. This document only restates existing requirements in this regard, stating them in 2119-language. It does not create any new requirement. Operates that clear the DF bit are already in violation of three standards-track RFCs. > Then, end users may actively act against PMTUD and/or IETF. I disagree; if they wanted to do so, they already would have acted since the requirements already exist, albeit in pre-RFC2199 language. Joe > > Masataka Ohta