Re: [re-ECN] RE-ECN without ECN.

[João Taveira Araújo <[e-mail]>]

Matt Mathis wrote:
>>>> For all modern reliable protocols over non-ECN networks (where loss is
>>>> the primary congestion indicator), the amount of duplicate data is a
>>>> direct measure of the down stream congestion.    (e.g. If I observe
>>>> both a data packet and its retransmission, then the first transmission
>>>> was lost someplace downstream).    This is because for all modern
>>>> protocols, the sender almost never sends data that the receiver
>>>> already holds.
>>>>
>>>>         
>>> Except it's not transport oblivious, so you'd have to a) redesign the
>>> solution for every new transport protocol or b) expect a single transport
>>> protocol to be all-encompassing. Won't nitpick since this is a thought
>>> experiment though...
>>>       
>
> Joao,
> Which do you think is harder: adding duplicate data detection for a
> new transport protocol to the ingress router or to get a (potentially
> hostile) new transport to carry the ECN information on its ACKs?  (See
> the ECI field for TCP Section 6.1.1 in -re-ecn-tcp- )   My bet that it
> is a lot easier to add the duplicate detection to the ingress router,
> since the owner is motivated to do so.
>
>   

I thought you were referring to the first, rather than last ISP, so I 
had construed your solution backwards, but even so doesn't this depend 
on the fate of non-re-ECN traffic? If non compliant traffic is treated 
in bulk as if it were misbehaving, the incentive would be for all 
transport protocols to adhere to re-ECN, in which case it wouldn't 
matter how hostile a transport protocol is, so long as it complies with 
the ISP's definition of acceptable behaviour [see Bob's ReArch paper].

Joao