NAT444 or ?

Leigh Porter leigh.porter at
Thu Sep 8 08:48:16 UTC 2011

> -----Original Message-----
> From: Owen DeLong [mailto:owen at]
> Sent: 08 September 2011 01:22
> To: Leigh Porter
> Cc: Seth Mos; NANOG
> Subject: Re: NAT444 or ?
> > Considering that offices, schools etc regularly have far more than 10
> users per IP, I think this limit is a little low. I've happily had
> around 300 per public IP address on a large WiFi network, granted these
> are all different kinds of users, it is just something that operational
> experience will have to demonstrate.
> >
> Yes, but, you are counting individual users whereas at the NAT444
> level, what's really being counted is end-customer sites not individual
> users, so the term
> "users" is a bit misleading in the context. A given end-customer site
> may be from 1 to 50 or more individual users.

Indeed, my users are using LTE dongles mostly so I expect they will be single users. At the moment on the WiMAX network I see around 35 sessions from a WiMAX modem on average rising to about 50 at peak times. These are a combination of individual users and "home modems".

We had some older modems that had integrated NAT that was broken and locked up the modem at 200 sessions. Then some old base station software died at about 10K sessions. So we monitor these things now..

> > I would love to avoid NAT444, I do not see a viable way around it at
> the moment. Unless the Department of Work and Pensions release their /8
> that is ;-)
> >
> The best mitigation really is to get IPv6 deployed as rapidly and
> widely as possible. The more stuff can go native IPv6, the less depends
> on fragile NAT444.

Absolutely. Even things like google maps, if that can be dumped on v6, it'll save a load of sessions from people. The sooner services such as Microsoft Update turn on v6 the better as well. I would also like the CDNs to be able to deliver content in v6 (even if the main page is v4) which again will reduce the traffic that has to traverse any NAT. 

Soon, I think content providers (and providers of other services on the 'net) will roll v6 because of the performance increase as v6 will not have to traverse all this NAT and be subject to session limits, timeouts and such.


This email has been scanned by the MessageLabs Email Security System.
For more information please visit 

More information about the NANOG mailing list