Re: [BEHAVE] Home NAPT44 - How many ports?

kaname nishizuka <kaname@nttv6.jp> Wed, 05 June 2013 18:16 UTC

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Date: Thu, 06 Jun 2013 03:15:57 +0900
From: kaname nishizuka <kaname@nttv6.jp>
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To: "Reinaldo Penno (repenno)" <repenno@cisco.com>
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Cc: "v6ops@ietf.org" <v6ops@ietf.org>, "behave@ietf.org" <behave@ietf.org>, "Poscic, Kristian \(Kristian\)" <kristian.poscic@alcatel-lucent.com>, "Softwires-wg list \(softwires@ietf.org\)" <softwires@ietf.org>, "Erik Kline \(ek@google.com\)" <ek@google.com>, "Rajiv Asati \(rajiva\)" <rajiva@cisco.com>
Subject: Re: [BEHAVE] Home NAPT44 - How many ports?
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With regard to the DNS packets, shortening the time-out of NAT table is 
another good solution.

In larger environment, we tested that when the time-out of DNS was 
shortened to 3sec, the impact of such DNS requests was much smaller than 
TCP sessions.
3 sec is sufficient  round-trip time in general situation.
I don't think it's necessary to place a recursive DNS server inside the CGN.

Though there are differences between Home NAPT44 and CGN, it will work 
well in both case.
That is because there are many devices in home and those seldom access 
the web site within a short time simultaneously.

regards,
--
kaname

(2013/06/06 1:27), Reinaldo Penno (repenno) wrote:
>
> On 6/5/13 1:23 PM, "Michael Richardson" <mcr+ietf@sandelman.ca> wrote:
>
>>>>>>> "repenno" == repenno  <Reinaldo> writes:
>>     repenno> On the other hand, as Rajiv captured,the number of
>>     repenno> UDP sessions can be much larger than the number of
>>     repenno> TCP. Because the way
>>     repenno> dynamic webpages are constructed today, there are sometimes
>>     repenno> literally 100s
>>     repenno> of DNS requests to download a single page.
>>
>> If one is doing CGN, wouldn't it be reasonable to point customers' at
>> a recursive DNS server with an interface inside the CGN?
> Yes. That's what I suggest. But some people use, say, Google's
> DNS/OpenDns/etc and in some other cases the network is not setup correctly.
>
>> This seems to also suggest that having a *caching* recursive DNS(SEC,
>> HOMENET+, mDNS+) server inside the customer router is also a big win.
> Yes, it is.
>
>> -- 
>> ]               Never tell me the odds!                 | ipv6 mesh
>> networks [
>> ]   Michael Richardson, Sandelman Software Works        | network
>> architect  [
>> ]     mcr@sandelman.ca  http://www.sandelman.ca/        |   ruby on rails
>>    [
>> 	
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-- 
----
Kaname Nishizuka
Innovative Architecture Center
NTT Communications Corporation
+81-50-3812-4704