Subject: RE: [ippm] Request for speaking slot:draft-anjali-ippm-avail-band -measurement-00.txt

From: Bennett Jon-MGIA0444 <[email-masked]>
Date: Fri, 8 Nov 2002 12:57:33 -0500

> > what happens when multiple people perform the test at the 
> same time? is the
> > available bandwidth = the available bandwidth? or = avail 
> bw / number
> > of testers?
> >
> 
> In a big network, the probability of two identical simultaneous events
> decreases with size. In other words, the probability of multiple users
> desiring path available bandwidth measurement simultaneously is low.

What do you base that statement on other then the fact that you would like
it to be true? What do you think the odds of more than one person probing
the bandwidth of the link to www.yahoo.com is? I would guess the probability
is ~1.0 

> However, in the rare case that this happens, it is desirable to have a
> conservative estimation of the path available bandwidth. If 
> the users are measuring the available bandwidth at an instant, it is 
> foreseeable that they will send traffic to use that measured value of 
> bandwidth. Thus, it is efficient to give to them a partial visibility
> of the total path available bandwidth.

its also probable that they were just performing a measurement, or that if
they transmit that it will not use the whole free capacity in which case
such an estimate will be wildly conservative.

> > one part that I was particularly scared by was
> >
> >
> > >It has to be noted that our scheme will have difficulty in
> > >   measuring bandwidth for paths with high capacity links. This is
>...
> > this strikes me as standardizing a DDOS mechanism :)
> >
> 
> Since there are no special features added by our method to a 
> simple TCP transfer, we are not adding any security concern. Sending a 
> TCP flow is a task that does not need any special privileges.

Well either you or someone is going to go and produce a "mechanism" to
perform this measurement in which case my statement holds, or no one is
going to make a mechanism to perform this measurement...... in which case
there is not much point in discussing it is there?

jon
_______________________________________________
ippm mailing list
[email-masked]
http://mailhost.advanced.org/mailman/listinfo/ippm