Thanks Nick for replying 
In the first question I was referring to the flowmod messagesreceived from the 
controller (not actual flows) that a hardware switch can process.
Does anyone have a rough approximate of this value for a hardware switch? (Just 
curious)
Is there any tool for measuring theperformance of a hardware switch ?
When can we expect support for version 1.1 by vendors? I am wondering if there 
are some chips which have hardware support for1.1 version or new chips need to 
be manufactured for this version.If latter, I think it would take some time 
right?
I suppose there would have been discussions with chipmanufactures prior release 
of ver 1.1 on the feasibility of certain actions.But first need to see if some 
vendor has full support for version 1.0.
Karthik

--- On Sat, 4/30/11, Nicholas Bastin <[email protected]> wrote:

From: Nicholas Bastin <[email protected]>
Subject: Re: [openflow-discuss] Questions on hardware switches
To: "karthik" <[email protected]>
Cc: [email protected]
Date: Saturday, April 30, 2011, 3:12 AM

On Sat, Apr 30, 2011 at 02:15, karthik <[email protected]> wrote:

I have some questions on openflow mainly related to vendor hardware switches 1. 
The open flow controllers seem to be getting more robust and powerful.
    I was wondering how many flows/sec can a hardware switch (Hp 
Procurve,Indigo etc)    process per second.
Do you mean flowmods, or actual flows through the switch fabric?  Generally the 
hardware switches can forward at line rate through any number of flow mods (the 
limiting factor usually being the size of the flow table, not the processing 
speed).  Obviously you should refer to the vendor specs for more precise 
information.
 
2. Can the controller overwhelm a hardware switch by sending packet out   ,flow 
mod and flow stat commands?
Very likely. 
If it can, does openflow protocol have some         mechanism where the switch 
and controller can exchange the limits of its 
    processing capabilities.Example if a switch can handle only say 50 flow mod 
msgs/sec    it can communicate to the controller at the
 initial handshake about this and controller    restricting the flows to this 
limit.
This is outside the scope of the spec - every device will behave differently 
and while controllers could encode this information, it's certainly not 
codified in the spec (different requests will have unknown requirements on CPU 
time, it would be hard to communicate this in a handshake). 
 
Last question, how many vendor switches support openflow now (ver 1.0 and 1.1) 
I don't believe any available hardware switches support 1.1 (at least not 
publicly) - this spec is very new and they've barely had time to read it, let 
alone implement it.

The only commercially available switches that I know of that support openflow 
out of the box are from Pronto and Netgear (there may very well be others I 
don't know about - don't count this list as exclusive by any means), although 
there are various other vendors who have experimental firmwares that you can 
likely acquire if you communicate with their sales staff.

--Nick
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