Re: question about IPv6 Flow label

[Hesham Soliman <hesham@elevatemobile.com>]

On 18/05/09 8:19 PM, "David Malone" <dwmalone@maths.tcd.ie> wrote:

> On Mon, May 18, 2009 at 03:22:46AM +0200, marcelo bagnulo braun wrote:
>> In the MEXT WG we are discussing about using the Flow Label as a flow
>> descriptor and we were wondering how widely implemented is RFC3697. In
>> particular, how many of the current OSes actually do:
> 
> I had a look at this a few years ago with Orla McGann, because we
> wanted to know if the flow label could be used by a stateful firewall:
> 
> http://www.maths.tcd.ie/~dwmalone/p/ec2nd05.pdf
> 
> It seemed that there were some problems where the flow label was
> not set consistently. We fixed this up in FreeBSD, so I can tell
> you what happens there. For TCP the flow label is usually set
> randomly, either using a hash of the connection details (+ a secret)
> or is set randomly using a PRNG. At the moment there isn't check
> to make sure the flow label is not shared between two flows.
> 
> For UDP, I think the flow label will default to zero.

=> Do you know why the same was not done for UDP?

Hesham

> 
> David.
>