Where to Use 240/4 Re: 202401100645.AYC Re: IPv4 address block

["Abraham Y. Chen" <aychen () avinta com>]

Hi, Michael:

1)    " ... While you may be able to get packets from point A to B in a 
private setting, using them might also be .. a challenge. ...   ":

    EzIP uses 240/4 netblock only within the RAN (Regional Area 
Network) as "Private" address, not "publicly" routable, according to the 
conventional Internet definition. This is actually the same as how 
100.64/10 is used within CG-NAT.

2)    However, this might be where the confusion comes from. With the 
geographical area coverage so much bigger, an RAN is effectively a 
public network. To mesh the two for consistency, we defined everything 
related to 240/4 as "Semi-Public" to distinguish this new layer of 
networking facility from the current public / private separation. That 
is, the CG-NAT routers will become SPRs (Semi-Public Routers) in EzIP's 
RAN, once the 240/4 is deployed.

Hope this helps,


Abe (2024-01-11 12:21)



On 2024-01-10 10:45, Michael Butler via NANOG wrote:
> On 1/10/24 10:12, Tom Beecher wrote:
> > Karim-
> >
> > Please be cautious about this advice, and understand the full context.
> >
> > 240/4 is still classified as RESERVED space. While you would 
> > certainly be able to use it on internal networks if your equipment 
> > supports it, you cannot use it as publicly routable space. There have 
> > been many proposals over the years to reclassify 240/4, but that has 
> > not happened, and is unlikely to at any point in the foreseeable future.
>
> While you may be able to get packets from point A to B in a private 
> setting, using them might also be .. a challenge.
>
> There's a whole bunch of software out there that makes certain 
> assumptions about allowable ranges. That is, they've been compiled 
> with a header that defines ..
>
> #define IN_BADCLASS(i)    (((in_addr_t)(i) & 0xf0000000) == 0xf0000000)
>
>     Michael


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