Re: [re-ECN] VIability issue #2

> -----Original Message-----
> From: re-ecn-bounces@ietf.org [mailto:re-ecn-bounces@ietf.org] On
> Behalf Of Leslie Daigle
> Sent: 05 November 2009 06:07
> To: re-ecn@ietf.org
> Subject: [re-ECN] VIability issue #2
> 
> 
> [This attempts to outline an issue that could be perceived as
> challenging the viability of congestion exposure work.  The goal is to
> capture the issue, as well as itemize reasonable supporting arguments
> (for viability) and remaining questions to be addressed.  Please
> respond
> with suggestions as needed for each section.  ]
> 
> Viability Issue #2
> 
> The expectation is that congestion exposure information will be
carried
> in IP packet headers.  Is there really enough room to do that
> effectively (in IPv4)?

Hopefully, but it is certainly tight... The key thing here is that the
IETF may have to actually decide the time has come to "unreserve" the
reserved flag! 

> 
> 
> For discussion:
> This assumes tight timing -- that feedback is received and acted upon
> such that subsequent flows will experience the same or similar network
> state.  What are the implications (or likelihood) of different paths?
> Or, are there other network state changes that will (could) change in
> that timeframe (now or in future developments).

There are issues to be resolved here about how quickly congestion may be
assumed to vary, how much impact a given flow may have on that
congestion level and as Leslie points out, the impact of path changes.
We also will later have to address how to aggregate and use the CONEX
info (eg using moving averages or counters...)

> 
> Leslie.
> 
> --
> 
> -------------------------------------------------------------------
> "Reality:
>       Yours to discover."
>                                  -- ThinkingCat
> Leslie Daigle
> leslie@thinkingcat.com
> -------------------------------------------------------------------
> _______________________________________________
> re-ECN mailing list
> re-ECN@ietf.org
> https://www.ietf.org/mailman/listinfo/re-ecn