Re: [Softwires] dual-stack-lite-06 - Too biased against static port sharing

[Rémi Després <[e-mail]>]

Hi Ralph,
More in line.

Le 12 août 2010 à 08:06, Rémi Després a écrit :

> 
> Le 12 août 2010 à 00:00, Ralph Droms a écrit :
> 
>> Rémi - please see responses in line...
>> 
>> - Ralph
>> 
>> On Aug 11, 2010, at 8:38 AM 8/11/10, Rémi Després wrote:
>> 
>>> Helo all,
>>> 
>>> Sec 8.4.1 says (asterisks added):
>>> "... thousands or tens of thousands of ports could be use in a peak by any single customer browsing a number of AJAX/Web 2.0 sites.  
>>> As such, service providers allocating a fixed number of ports per user should dimension the system with a minimum of N = several thousands of ports for every user.  This would bring the address space reduction ratio to a single digit.  Service providers using a smaller number of ports per user (N in the hundreds) should expect customers applications to break in a more or less random way over time.
>>> In order to achieve higher address space reduction ratios, *it is recommended that service provider do not use this cookie-cutter approach, and, on the contrary, allocate ports as dynamically as possible, just like on a regular NAT*."
>>> 
>>> This is more biased against fixed number of ports per customer than technically appropriate, at least for the three reasons below. (Besides, such a bias isn't needed to justify the DS-lite specification): 
>>> 
>>> 1. The text should take into account that "over time" more and more servers will have IPv6, and that the full 64K ports are available in IPv6. (The mentioned AJAX/Web 2.0 sites would typically enable IPv6 asap, if not done yet. This will prevent problems over time.)
>> 
>> traffic to IPv6 servers just bypasses dual-stack lite altogether, right, so the limitation doesn't apply to that traffic?

Exactly.
Thus, dual-stack hosts will need time less and less IPv4 ports.
Suggesting in an RFC that they may need over time several thousands IPv4 ports would therefore be misleading.

>> 
>>> 2. If the number of assignable IPv4 addresses is for a start multiplied by 10, by statically sharing ports of each address among 10 customers, this still leaves several thousands of IPv4 ports per customer. (Exactly 6144 ports per customer if, as appropriate, the first 4K ports, that include well-known ports and have special value are excluded). 
>> 
>> Agreed; one could argue that even sharing an IPv4 address among 5 customers allows 5x as many customers in the existing IPv4 address assignment, which should be more than enough to bridge the gap until IPv6 is available.
>> 
>>> 3. Where applicable static sharing is much simpler to operate.
>> 
>> Agreed.
>> 
>>> If the principle is agreed, I can propose detailed words myself to improve the draft.

Is it right, then, that you welcome the proposal to revise the text?

Regards,
RD


>>> 
>>> Regards,
>>> RD
>>> 
>>> 
>>> Le 11 août 2010 à 00:30, [e-mail] a écrit :
>>> 
>>>> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>>>> This draft is a work item of the Softwires Working Group of the IETF.
>>>> 
>>>> 
>>>> 	Title           : Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion
>>>> 	Author(s)       : A. Durand, et al.
>>>> 	Filename        : draft-ietf-softwire-dual-stack-lite-06.txt
>>>> 	Pages           : 34
>>>> 	Date            : 2010-08-10
>>>> 
>>>> This document revisits the dual-stack model and introduces the dual-
>>>> stack lite technology aimed at better aligning the costs and benefits
>>>> of deploying IPv6 in service provider networks.  Dual-stack lite
>>>> enables a broadband service provider to share IPv4 addresses among
>>>> customers by combining two well-known technologies: IP in IP (IPv4-
>>>> in-IPv6) and Network Address Translation (NAT).
>>>> 
>>>> A URL for this Internet-Draft is:
>>>> http://www.ietf.org/internet-drafts/draft-ietf-softwire-dual-stack-lite-06.txt
>>>> 
>>>> Internet-Drafts are also available by anonymous FTP at:
>>>> ftp://ftp.ietf.org/internet-drafts/
>>>> 
>>>> Below is the data which will enable a MIME compliant mail reader
>>>> implementation to automatically retrieve the ASCII version of the
>>>> Internet-Draft.
>>>> <Pièce jointe Mail>_______________________________________________
>>>> Softwires mailing list
>>>> [e-mail]
>>>> https://www.ietf.org/mailman/listinfo/softwires
>>> 
>>> 
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>> 
>