Re: [v6ops] PMTUD issue discussion

[Fernando Gont <[e-mail]>]

On 08/26/2014 01:33 PM, Templin, Fred L wrote:
>> FWIW, I'm all in favor of RFC4821, since it improves robustness of PMTUD.
>>
>> That said, as far as I can recall, using RFC4821 for blackhole detection
>> (when traditional PMTUD fails) is well within the spirit of RFC4821
>> (RFC4821 doesn't push ICMP-less as the only implementation strategy).
>>
>> What I recall from discussing this with Linux developers circa 2005 is
>> that a complete ICMP-less PMTUD is rather undesirable, since it tends to
>> have longer convergence time when compared with "traditional PMTUD" ||
>> "Traditional PMTUD + RFC4821 for blachole detection".
> 
> Accepting and processing PTBs as part of the PLPMTUD procedure is
> desirable and speeds convergence. But, the mechanism still needs to
> work when there are no PTBs.
> 
> So, the network should still do its best to return PTBs, and hosts
> should still do their best to observe them.

Agreed. IIRC, this behavios has been implemented in Windows and OpenBSD
for 5+ years, though.

-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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