At 23:04 04/11/2013, Andrew Mcgregor wrote:
> This seems like valuable work.  One question is, can we put in scope 
> notification that losses are NOT due to congestion?

Speaking for myself, I'm not sure how I would do that.

A loss (or mark) due to congestion is pretty simple. The switch knows what it 
did. 

To know that a packet was lost for reasons other than congestion, I need to 
somehow know what packets I should expect, and infer that something that I 
expected didn't happen. In TCP, we know about data segments because they are 
enumerated - I know what the next octet sequence number to expect, and it 
doesn't arrive. Control segments (SYN, ACK, FIN, RST, and so on) are not 
enumerated in that sense - if my peer sends ten identical acks and nine arrive, 
I as the receiver have no way to know that. At the link layer, most link 
protocols in use today (PPP, Ethernet, and so on) do not enumerate packets in 
flight - they are simply there. I *might* be able to see a burst of noise on 
the line, but only if it looks like it might be the start of a packet and then 
doesn't end with the right checksum. Even if I can see it, I have no way to 
know whether the noise garbled one packet or many.

If you want to do some research and come up with a solution, be my guest. But 
in a standard discussed in 2013... let's not.

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