Re: [tcpm] review of draft-zimmermann-tcpm-reordering-detection

Hi Wes,

thanks a lot for looking into the draft! Comments below.

> Am 05.02.2015 um 20:48 schrieb Wesley Eddy <wes@mti-systems.com>:
> 
> I reviewed the reordering detection algorithm document:
> https://tools.ietf.org/html/draft-zimmermann-tcpm-reordering-detection-02
> 
> The document is very well written.  The specification in the draft seems
> quite clear and like it would be easy to implement directly from the
> document.
> 
> The purpose of section 4.7 ("Placeholder for Response Algorithm") isn't
> clear to me, especially in relation to the separate reaction draft
> (draft-zimmermann-tcpm-reordering-reaction).

The purpose of section 4.7 is to have a hook for a further reordering
reaction algorithm. RFC 4015 has something similar. However, Eifel
reaction is maybe a bit more explicit and clear at this point (see step
(DET) in RFC 4015)

> 
> One thing that was unclear to me, and seems useful, is a discussion of
> the potential sources of error.  In other words, what events would
> cause the computed metrics to be wrong and how significantly wrong?
> There are a number of different events and potential corner cases that
> are already addressed in the algorithm, and it wasn't clear to me
> "what's left" or if it's supposed to just work perfectly in all cases.
> (I’m sure it's not!)

Very good point! I agree. We will add some text in the next version.

> 
> Obvious things that occurred to me were:
> - different compositions of loss and reordering "features" in the
>  forward path:
>  - lossiness followed by reordering
>  - reordering followed by lossiness
>  - reordering followed by reordering somewhere else (and do we even
>    care about this, since it's the state of the packets at the
>    receiver that matters, and not how many times the order has been
>    shuffled)
> - loss and reordering in the ACK path

+ packet duplication

> 
> The sensitivity to these things, I think, matters in understanding the
> utility of the computed metrics, and their feedback into a response
> function.

I agree.

Have a nice WE
Alex

> 
> 
> --
> Wes Eddy
> MTI Systems
> 
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Re: [tcpm] review of draft-zimmermann-tcpm-reordering-detection

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