[e2e] [tcpm] Question on RFC6298, Managing the RTO Timer and additional lost pakets in Recovery state

[Michael Welzl]

> On 03 Mar 2016, at 15:54, Michael Welzl <michawe at ifi.uio.no> wrote:
> 
> 
>> On 03 Mar 2016, at 15:31, Mark Allman <mallman at icir.org> wrote:
>> 
>> 
>>> It says quote “(5.3) When an ACK is received that acknowledges new
>>> data, restart the retransmission timer so that it will expire after
>>> RTO seconds (for the current value of RTO).”
>>> 
>>> What is the definition of new data ?. The strict interpretation is
>>> when SND.UNA advances, but it can also be that the highest SACKed
>>> sequence number increases. The former case it is more likely that
>>> RTO happens. 
>> 
>> Seems like something we should have nailed down in the spec at some
>> point after SACK became widely prevalent.  Alas.
>> 
>> I think "new data" can be interpreted as "cumulative ACK advances".
> 
> This "new data" stuff is also all over RFC 5681. I remember being confused by it long ago, exactly with the same two possible interpretations that Ingemar writes below.
> Back then I assumed that it must be me; I'm glad to see that I'm not the only one who got confused by this.

... and what can you expect from a guy who can't even get "above" vs. "below" right?

Sigh... sorry folks

Michael