Subject: [cso] Some thoughts from the CSO Bar BOF...

From: Greg Bernstein <[email-masked]>
Date: Tue, 09 Nov 2010 12:28:20 -0800

Hi folks interested in cross stratum optimization (CSO) a few thoughts 
on some of the interesting points raised at the Bar BOF and to possibly 
stimulate further discussion:

(a) Who benefits from CSO? The application provider or the carrier? It 
seems to be viable CSO should benefit both. The network operator 
(carrier, ISP, IT department, etc...) should benefit from more effective 
utilization of network resources (links, switches, routers, etc...) and 
gain more flexibility in dealing with fault conditions. The application 
provider benefits from being able to offer either higher quality 
services or better assurances on service quality. Essentially the 
network operator gets to influence the placement of load on the network 
while the application provider gets information that allows them to 
optimize their resources along with their customers experience.

(b) Isn't the Internet "best effort"? How can you talk of providing a 
better "network experience" to applications?
First CSO isn't strictly aimed at the "Internet" in general, but would 
start with various network domains (LAN, OSPF area, AS, etc...). Also 
"best effort" is a somewhat misleading term since it doesn't take into 
account overall statistical quality measures that are very important to 
user experiences. For example 2000 sessions sharing a link on a first 
come first serve basis are considered "best effort" whether the link is 
a T1 or an OC-192 but will generally experience greatly different 
"average" QoS ;-) . Depending on the network context and technology 
various service level guarantees may be explicit or implicit.

(c) What's a "data center" and do we include "hosts"? Folks interested 
in CSO come from a number application and network areas.  The essence is 
that guidance from the network provider to the application provider 
concerning network state and capability provides benefits to both. In 
one of the drafts we tried a definition of a "data center" as something 
like "a location within the network where application resources maybe 
aggregated".
I'd say a "host" (or my laptop) would qualify. Other ideas?

(d) Examples? During some of the background work for the CSO drafts we 
looked at a number of examples that we published in the original draft. 
We've also looked at "pre-CSO" type mechanisms that are being used to 
try and optimize applications. These include "old school" and "new 
school" CDN approaches,  load balancing within and between data centers 
(local versus global),  various papers dealing with local and wide area 
VM migration, and High Performance Computing applications (radio 
astronomy being an interest of mine). Would it be useful to organize 
these in some way? We had some of these in the original CLO draft but 
the overall length was getting to long.  For our WSON work we set up web 
pages to keep track not just editors copies of our drafts (for all to 
work with) but supplemental material (some of which was later published 
in IEEE/OSA journals).

Just some thoughts from a jet lagged Californian ;-)

Greg B.

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Dr Greg Bernstein, Grotto Networking (510) 573-2237