Subject: RE: [ippm]Comments on initial rough draft of capacity definitions

From: "Fardid, Reza" <[email-masked]>
Date: Tue, 8 Mar 2005 13:26:41 -0800

Phil,

2544 and 3918 may be relevant as far as throughput is concerned.

Thanks,
Reza

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] 
Sent: Monday, March 07, 2005 5:33 PM
To: Fardid, Reza
Cc: [email-masked]
Subject: Re: [ippm]Comments on initial rough draft of capacity definitions

Hi Reza:

Thanks for your comments.
We'll try to be more consistent in the next draft...
Is there a specific BM RFC that you are referring to?

On Mar 7, 2005, at 18:27, Fardid, Reza wrote:

> Phil,
>
>  
>
> A couple of comments on this draft:  
>
>   
> 	1.  	Only metrics defined should be referred to, or otherwise all 
> terms used should be defined: effective capacity and throughput (2.3), 
> vs.
>
>  available capacity and utilization (3).
> 	2.  	Even though the scope of IPPM and BM WGs is different, terms 
> defined by the latter WG, such as throughput may be relevant in the 
> context of this ID.
>
>  
>
> Regards,
>
> Reza Fardid
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---

From: Federico Montesino Pouzols <[email-masked]>
Date: Wed, 9 Mar 2005 14:01:15 +0100

Hi all, I also have some general comments on the draft:

a) I would suggest updating the reference [PDM] to a more recent,
(extended and updated) work on the subject by the same authors:

Dovrolis, C., Ramanathan, P. and D. Moore, "Packet dispersion
techniques and a capacity estimation methodology", IEEE/ACM
Transactions on Networking 12(6): 963-977, December 2004.

b) Following the aforementioned reference, and other works from the
same and different authors, I understand that what is called
'Available Capacity' in the draft is usually called 'Available
Bandwidth'. Is there any reason for choosing another term?

c) For the Abstract section (and as point of view for the whole
draft), I think it would be clearer to talk of capacity as a metric
that describes a the state of a network link/path at a given time
rather than IP traffic.

Regards.

---

From: [email-masked]
Date: Wed, 09 Mar 2005 08:28:51 -0600

Federico: Thanks. Responses inline.

> Transactions on Networking 12(6): 963-977, December 2004.
Thanks for the reference. I'll use the updated reference in the next 
draft.

> Bandwidth'. Is there any reason for choosing another term?

Yes. We chose capacity because bandwidth is a term that covers lots of 
things and is easily misunderstood. Suppose that you have and RF link. 
Is the bandwidth the frequency band in which you transmit (Hz), the raw 
information-carrying capacity (bps), the information carrying capacity 
minus redundancy coding and physical layer overhead (bps), etc, etc. We 
are actually defining is the information carrying capacity as seen by 
the IP layer. Hence the choice of terminology and qualifications (i.e. 
IP layer ....).

> that describes a the state of a network link/path at a given time

We agreed in the WG that in this draft, we were not going to try to 
define metrics, but focus on very precisely defining the quantities of 
interest, rather than how to measure them. That is a hard enough task 
for the short term :-)

Regards,
Phil Chimento

---

From: Joseph Ishac <[email-masked]>
Date: Wed, 9 Mar 2005 12:07:43 -0500

Some further comment on (b):

We originally called 'available capacity' 'available bandwidth', and we
ran with the former term as Phil explained in his note.

However, we did have a snip-it of text that was removed that indicated
the common interchangeability of the two terms.  Perhaps we can work that
back into the draft?

-Joseph

---

From: Federico Montesino Pouzols <[email-masked]>
Date: Thu, 10 Mar 2005 14:07:59 +0100

> the common interchangeability of the two terms.  Perhaps we can work that

I think yes, a short note clarifying that the term chosen is different
to that of many papers and works (particularly the reference [PDM])
would avoid confusion. By the way, I do also prefer 'available
capacity' :)