On Sat, 25 Aug 2018, Toerless Eckert wrote:
On Fri, Aug 03, 2018 at 09:48:25AM +0200, Mikael Abrahamsson wrote:
I've kept saying "Networks must support ip fragmentation properly.
Why ? Wheren't you also saying that you've got (like probably many
else on this thread) all the experience that only TCP MSS gets you
working connectivity in many case (like hotels) ?
Correct. The reason for this is that whatever we design must be resilient
to failure. Networks should work properly, but applications should
handle it when they don't. Degraded performance is ok.
IMHO, we (network layer) should accept defeat on network layer
fragmentation and agree that we should make it easier for the
transport layer to resolve the problem.
I want to keep the fragmentation requirement for the network.
Aka: I would lvoe to see a new ICMPv4/ICMPv6 reply and/or PTB reply option
indicating "Fragmented Packets Not Permitted". Any network device which
for whatever reason does not like Fragemnts would simply drop
fragmented packets and send this as a reply. Allows then the
transport layer to automatically use packetization (such as TCP MSS)
to get packets through.
I am not opposed to this option being created, but you still need PLPMTUD.
This option might trigger faster PLPMTUD, but it doesn't make the problem
go away. If the application still keeps sending packets that needs to be
fragmented, what should the stack do, just send an error to the
application? Yes, this will mean we will fail faster, but apart from that?
--
Mikael Abrahamsson email: swm...@swm.pp.se
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