[conex] Accounting of ConEx signals

[Mirja Kühlewind <[e-mail]>]

Hi everybody,

Richard and I are currently working on the TCP modifications draft. And we get 
always stocked at the same question how the accounting of the ConEx signal 
should be done. I believe we assume that the ConEx signal is counted 
byte-wise that means all bytes of a marked packet are assumed to expose the 
link congestion. First of all, I have to say hat this is nowhere officially 
defined. That lead to the following couple of questions:

1. Where do we need to define this? In the IPv6 doc? 
Because it might be a more general question and it must be clear to everyone 
that if we account the signal byte-wise this has to be done in the endsystem 
as well as in every network device using this information.

2. Which bytes of a packet do we take? The IP length incl header, the IP 
payload incl. TCP header or the actual payload?
In TCP if a packet get lost (with SACK) we only know how many payload got 
lost. We do not know the number of packets/headers that were used to transmit 
this data. If we would loose one big packet and then retransmit a large 
number of small packets instead (which are all ConEx marked) that might give 
quite a different ConEx signal. On the other hand, what causes the congestion 
is the whole packet incl header(s). What is the right thing to do?

Input is very welcome!

Thx,
Mirja