Where does this "You can only have about 200-300 subscribers per IPv4 address on a CGN." limit come from? I have seen several apartment complexes run on a single static IPv4 address using a Mikrotik with NAT.
On Wed, Sep 22, 2021 at 2:49 PM Baldur Norddahl <baldur.nordd...@gmail.com> wrote: > > > > On Wed, 22 Sept 2021 at 16:48, Masataka Ohta > <mo...@necom830.hpcl.titech.ac.jp> wrote: >> >> Today, as /24 can afford hundreds of thousands of subscribers >> by NAT, only very large retail ISPs need more than one >> announcement for IPv4. > > > You can only have about 200-300 subscribers per IPv4 address on a CGN. If you > try to go further than that, for example by using symmetric NAT, you will > increase the number of customers that want to get a public IPv4 of their own. > That will actually decrease the combined efficiency and cause you to need > more, not less, IPv4 addresses. > > Without checking our numbers, I believe we have at least 10% of the customers > that are paying for a public IPv4 to escape our CGN. This means a /24 will > only be enough for about 2500 customers maximum. The "nat escapers" drown out > the efficiency of the NAT pool. > > The optimization you need to do is to make the CGN as customer friendly as > possible instead of trying to squeeze the maximum customers per CGN IPv4 > address. > > Perhaps IPv6 can lower the number of people that need to escape IPv4 nat. If > it helps just a little bit, that alone will make implementing IPv6 worth it > for smaller emerging operators. Buying IPv4 has become very expensive. Yes > you can profit from selling a public IPv4 address to the customer, but there > is also the risk that the customer just goes to the incumbent, which has old > large pools of IPv4 and provides it for free. > > Regards, > > Baldur >
