[Ecn-sane] The two SCE tests I have in mind

[Pete Heist]

> On Mar 24, 2019, at 12:08 PM, Jonathan Morton <chromatix99 at gmail.com> wrote:
> 
>> On 24 Mar, 2019, at 12:05 pm, Pete Heist <pete at heistp.net> wrote:
>> 
>> tcpdump -r file.pcap udp port 2112 and greater 80 and "ip[1] != 0x1”
>> 
>> “greater 80” ignores the handshake packets and 0x1 is whatever TOS value we want to make sure the packets contain. We can use different filters for other traffic.
> 
> Bear in mind that the TOS byte contains ECN as well as DSCP fields, and the latter is left-justified.


Indeed, I was playing with irtt to see if it gladly writes the whole field including the ECN bits (it does). Better common examples we can test for DSCP could be 0x10 or 0xb8.