Subject: [re-ECN] What Comcast's FairShare Solution does not provide...

From: "Tschofenig, Hannes (NSN - FI/Espoo)" <[email-masked]>
Date: Thu, 4 Mar 2010 12:17:05 +0200

Bob pointed to a slide set by Ric that talks about the Comcast
congestion management solution. Here is the slide set: 
http://giic.org/pdf/GIIC-CapShare-01-Woundy-Comcast.pdf

I tried to re-word the arguments to avoid the solution specific touch. 

Ric provided a few arguments what he believes is missing from their
current solution that might require future work: 

* Comcast's FairShare approach is not an end-to-end solution

I would say: So what? As an argument for an ISP that has a problem to
solve now that's probably not an interesting argument for further work. 

* It does not signal congestion to user applications nor to devices
along the path. 

True. 

Only devices within the Comcast network would see the DiffServ marking
when the increased traffic leads to traffic marking (from PBE to BE). 

* It does not enable application response. 

I don't agree with that. Packet dropping will give applications an
implicit indication. 

* Re-ECN enables DDoS mitigation and other capabilities

This is too unspecific to me to convince anyone. 

Do we have a few more arguments? 

Ciao
Hannes

---

From: "Woundy, Richard" <[email-masked]>
Date: Thu, 18 Mar 2010 02:31:04 -0400

Hannes,

I want to re-visit one point in this email.

Fairshare focuses on the broadband access network, and it does a
reasonable job at that. (It would be nice to incentivize LEDBAT of
course, but that's another point.)

While a lot of our internal focus has been on broadband access
congestion, that's not the only congestion point that impacts our
customers' experience. Another potential spot for congestion can be the
interconnects between backbones. What makes interconnects unique is that
they require coordination between two parties, whose business interests
and priorities are not necessarily aligned. One party may be more
concerned about congestion over a particular interconnect link that the
other party, but both parties need to cooperate for any upgrade.

In the year following our deployment of Fairshare, we were accused
several times of blocking or throttling specific application traffic (I
won't name them here). From what I understand, the root cause was traced
to either interconnect congestion or overload conditions in application
data centers.

That's why end-to-end visibility of congestion would be quite useful to
us.

-- Rich

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Tschofenig, Hannes (NSN - FI/Espoo)
Sent: Thursday, March 04, 2010 5:17 AM
To: [email-masked]
Subject: [re-ECN] What Comcast's FairShare Solution does not provide...

True. 

Ciao
Hannes
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