On Wed, Jul 26, 2023 at 5:09 PM Robert Edmonds <edmo...@mycre.ws> wrote:
> George Michaelson wrote: > > if QDCOUNT is defined as [0|1] then we have 15 new bits of freedom in > > the header. > > > > What would be interesting uses of the flow-label? Oh wait.. that's > > right, nobody really knows at scale how to use flow-label either. > > > > I tend to "use it for 15 bits of signalling" because there are a lot > > of things I wish were signalled from client to server. > > > > "I am new code" > > "I am at least not ancient code" > > "I'm the same as that other guy you saw over <there>" > > "I like TCP and want to do a persisting session" > > "tell me if you are doing a|b|c|d" > > "I like chocolate and want a pony" > > > > maybe the truth is, we've got 15 bits of zero in the header forever, > amen. > > > > (I deliberately didn't put this in the draft- post from Ray so as not > > to pollute an objective discussion of what it is or is not the value > > proposition) > > > > clue-stick hits welcome. Avoid the stomach. > > > > -G > > With a maximum length QNAME inside a UDP query packet there are slightly > under a couple thousand bits available for EDNS. Those bits at the end > of the packet are easier to get to, ecosystem-wise, so if those use > cases are worthwhile they should probably be done with EDNS. > > It depends. E.g. one variable in the mix is UDP fragmentation, which can put the EDNS component outside the first fragment. Header bits are always in the first fragment, so depending on the specific attack scenario and deployment state of things (like avoid-fragmentation), entropy in the first packet is still valuable. Brian
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