Subject: RE: [PCN] Off list: Comments on re ecn border cheat

From: "Geib, Ruediger" <[email-masked]>
Date: Fri, 12 Jan 2007 17:35:57 +0100

Bob,

thanks for the helpful explanations. Yes, I'd be interested in 
working on an ID on re-ECN for PCN domains. Some more 
comments in line.

[Snip]

R>To sum up, I'd prefer a deeper analysis of the scenarios
|>and architectures around cheating before discussing
|>solutions.

Bob:
|Certainly. I tried to write up both the problem and the 
|solution, so that anyone who cared to read it all could 
|start to satisfy themselves that PCN potentially had 
|enough legs to go beyond just an intra-domain scenario.

Yes, going beyond an intra-domain scenario and allowing 
transits for bulk PCN service is a useful aim. 

|I would be very happy to take a more measured approach to this 
|whole area, if others are interested too. In that case, 
|yes, we should start with a problem statement alone. 
|I suggest the general problem is how to police 
|microflow admission control at borders without per-flow 
|processing. Or we could limit the scope of the problem 
|to a PCN context.

I got the second last sentence and agree with you. I'm not sure, 
whether I understand what you mean by "limiting the scope 
to a PCN context." If you want to say, let's focus on the 
kind of service which is specified by the current PCN WG, 
I agree too.

|
|Even though this isn't yet PCN chartered work, would you be 
|interested in working on an I-D on this with me in 
|parallel to the PCN w-g, so it's ready 
|for when the PCN group re-charter in about a year's time?

As I mentioned, I'd be willing to work on such an I-D.

|Once the problem is clarified, we should see if we can dream up other 
|solutions. However, policing of a response to network layer 
|congestion by the transport was a very hard problem to solve elegantly. 
|Solving it across an internetwork has been much much harder. 
|So I suspect any alternative solutions are going to look pretty 
|similar to this one, unless someone makes an innovative breakthrough.

Probably my command of English is a little to weak here. By "policing" 
you don't refer to a network functionality called "policer", you 
rather mean "sanction" or "punish" in a more general sense? 

There's probably more like the above, where text is worrying me. 
Maybe trying  strictly apply a terminology through 
the document would help? The other example I just discovered is a 
sentence of section 5.4 saying:

"...the ingress gateway...will have to put twice as much congestion 
marking into the packets...."

The feature which is meant is "RE-blanking", isn't it? In 4.3.1 your 
text says "To avoid confusion we will use the term "blanking" 
(rather than marking)..."

Looks a little like pea counting here...so don't get me wrong, I think 
the RE-feedback and RE-blanking is a good idea and a better one is 
instantly hard to imagine. While I think to have understood the 
fundamental idea, some parts of the text result in making me 
question whether I really got it.

Regards,

Ruediger

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