Subject: Re: [BEHAVE] Fwd: New Version Notification for draft-nishizuka-cgn-deployment-considerations-00.txt

From: "Rajiv Asati (rajiva)" <[email-masked]>
Date: Thu, 9 May 2013 12:19:01 +0000

Hi Simon,

> An ISP is running out of addresses. It considers two options: static CGN
> vs dynamic CGN. Static allows, let's say, 32 users per public IPv4
> address. Given the 1:10 figure from the draft, it follows that dynamic
> allows 320 users per public IPv4 address.

1:32 (dynamic assignment) on top of 1:10 (static assignment)? Did you
intend to nest?

Could you please clarify?

Cheers,
Rajiv

-----Original Message-----
From: Simon Perreault <[email-masked]>
Date: Thursday, April 4, 2013 5:49 AM
To: Behave WG <[email-masked]>
Subject: Re: [BEHAVE] Fwd: New Version Notification
for	draft-nishizuka-cgn-deployment-considerations-00.txt

>Le 2013-04-03 20:57, Senthil Sivakumar (ssenthil) a écrit :
>> If it is not the address, what is the limiting factor? The reason ISP
>> is deploying CGN is the shortage of addresses and cant provide a
>> single address to each of his subscribers. Maybe you meant to say the
>> address is not the only limiting factor. I never said the text was
>> saying static isnt good enough :-), I deduced from the study that the
>> usage of ports is far more compellingly efficient with dynamic port
>> allocation and the cost of logging infra can be justified.
>
>I'll try to illustrate my point with an example with numbers.
>
>An ISP is running out of addresses. It considers two options: static CGN
>vs dynamic CGN. Static allows, let's say, 32 users per public IPv4
>address. Given the 1:10 figure from the draft, it follows that dynamic
>allows 320 users per public IPv4 address.
>
>If 32 is "enough", why suffer the trouble of logging (among others) just
>to get to 320? If 32 and 320 are both "enough", then considerations
>other than efficient use of public IPv4 addresses must take priority.
>
>"Enough" could mean something like "enough to support projected growth
>for X years".
>
>> Most of the studies in the past projected how bad the logging problem
>> is but didn¹t have any data on the other side of the equation on how
>> inefficient the static port allocation is. I wouldn¹t want this draft
>> to say one is better than the other, but let the operators choose, if
>> 10:1 static to dynamic port allocation is justified for their
>> deployment.
>
>The 10:1 figure is useful. However, the conclusion "therefore dynamic is
>better" is premature. There are tons of other criteria to consider. Even
>worse, it is very possible that the 10:1 figure does not even matter: if
>static is "good enough", you may not care that dynamic is 10 times better.
>
>Simon
>-- 
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---

From: Simon Perreault <[email-masked]>
Date: Mon, 13 May 2013 13:46:35 +0200

> Could you please clarify?

The draft says that the achievable address sharing ratio for dynamic is 
10x that of static. So if you have 1:32 for static (a made up figure), 
it follows you would have 1:320 for dynamic.

Simon

---

From: kaname nishizuka <[email-masked]>
Date: Wed, 15 May 2013 13:20:48 +0900

Yes. Based on the port consumption trend, we figured out that the 
sharing ratio of dynamic assignment is 10 times of that of static 
assignment.
However, I'm not intended to conclude that which is preferable in the draft.
That depends on the provider's choice.
I would carefully remove confusing representations.

regards,
kaname

(2013/05/13 20:46), Simon Perreault wrote:
> The draft says that the achievable address sharing ratio for dynamic 
> is 10x that of static. So if you have 1:32 for static (a made up 
> figure), it follows you would have 1:320 for dynamic.
>
> Simon

-- 
----
Kaname Nishizuka
Innovative Architecture Center
NTT Communications Corporation
+81-50-3812-4704

---

From: "Rajiv Asati (rajiva)" <[email-masked]>
Date: Wed, 15 May 2013 10:48:23 +0000

the achievable address sharing ratio for dynamic is 10x that of static.

I find this to be quite higher than what I would consider generically speaking.

Perhaps, we need to differentiate between mobile and wireline deployments.

Irrespective of that, I wonder the usefulness of static vs dynamic ratio, and how it could help in any CGN deployment. The question many deployments often ask is about the CGN pool size(s). We should qualify and quantify the answer to that question in this draft.

Cheers,
Rajiv

Sent from my Phone

On May 15, 2013, at 12:20 AM, "kaname nishizuka" <[email-masked]<mailto:[email-masked]>> wrote:

Yes. Based on the port consumption trend, we figured out that the sharing ratio of dynamic assignment is 10 times of that of static assignment.
However, I'm not intended to conclude that which is preferable in the draft.
That depends on the provider's choice.
I would carefully remove confusing representations.

regards,
kaname

The draft says that the achievable address sharing ratio for dynamic is 10x that of static. So if you have 1:32 for static (a made up figure), it follows you would have 1:320 for dynamic.

Simon
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