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

"Rajiv Asati (rajiva)" <rajiva@cisco.com> Wed, 05 June 2013 19:07 UTC

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From: "Rajiv Asati (rajiva)" <rajiva@cisco.com>
To: kaname nishizuka <kaname@nttv6.jp>, "Reinaldo Penno (repenno)" <repenno@cisco.com>
Thread-Topic: [BEHAVE] Home NAPT44 - How many ports?
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Date: Wed, 5 Jun 2013 19:04:43 +0000
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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>
Subject: Re: [BEHAVE] Home NAPT44 - How many ports?
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Kaname-san,

That's a good suggestion, though the captured data suggests that UDP NAT exhaustion is not a problem, but TCP NAT is.


Cheers,
Rajiv


> -----Original Message-----
> From: kaname nishizuka [mailto:kaname@nttv6.jp]
> Sent: Wednesday, June 05, 2013 2:16 PM
> To: Reinaldo Penno (repenno)
> Cc: Michael Richardson; v6ops@ietf.org; Softwires-wg list
> (softwires@ietf.org); Poscic, Kristian (Kristian); behave@ietf.org; Erik Kline
> (ek@google.com); Rajiv Asati (rajiva)
> Subject: Re: [BEHAVE] Home NAPT44 - How many ports?
> 
> 
> 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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> > Behave@ietf.org
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> 
> 
> --
> ----
> Kaname Nishizuka
> Innovative Architecture Center
> NTT Communications Corporation
> +81-50-3812-4704