nanog mailing list archives

Re: Streamline the CG-NAT Re: 202401101433.AYC Re: EzIP Re: 202401100645.AYC Re: IPv4 address block


From: Christopher Hawker <chris () thesysadmin au>
Date: Fri, 12 Jan 2024 23:30:46 +1100

"Source NAT changes the source address in IP header of a packet. It may
also change the source port in the TCP/UDP headers. The typical usage is to
change the a private (rfc1918) address/port into a public address/port for
packets leaving your network."

"Destination NAT changes the destination address in IP header of a packet.
It may also change the destination port in the TCP/UDP headers.The typical
usage of this is to redirect incoming packets with a destination of a
public address/port to a private IP address/port inside your network."

Source:
https://serverfault.com/questions/119365/what-is-the-difference-between-a-source-nat-destination-nat-and-masquerading

Regards,
Christopher Hawker

On Fri, 12 Jan 2024 at 23:17, Abraham Y. Chen <aychen () avinta com> wrote:

Hi, Christopher:

1)   "  destination/source NAT  ":

    I am not sure about this terminology. Could you please elaborate? If
you are referring EzIP being a bigger CG-NAT, it is exactly correct. That
is, the first step of EzIP implementation is just to give CG-NAT a larger
netblock to work with, so that the chore of dynamic address assignment to
the client may be avoided.

Regards,

Abe (2024-01-12 07:16)



On 2024-01-11 22:46, Christopher Hawker wrote:

Not going to lie, EzIP just seems to be some version of destination/source
NAT on steroids.

Regards,
Christopher Hawker

On Fri, 12 Jan 2024 at 14:36, Abraham Y. Chen <aychen () avinta com> wrote:

Hi, Forrest:

0)    Thanks for your in-depth analysis.

1)     However, my apologies for not presenting the EzIP concept clearer.
That is, one way to look at the EzIP scheme is to substitute the current
100.64/10  netblock in the CG-NAT with 240/4. Everything else in the
current CG-NAT setup stays unchanged. This makes each CG-NAT cluster 64
fold bigger. And, various capabilities become available.

Regards,

Abe (2024-01-11 22:35)



On 2024-01-11 02:02, Forrest Christian (List Account) wrote:

I shouldn't probably go down this path... as I know this has been
discussed but I'm hoping that this might make a difference.

Abraham,

Even if 240/4 is "fixed", your EzIP scheme will require some sort of NAT
box between the 240/4 addressed devices and the non-EzIP internet.  That
NAT box will have to remain in place until such time as every single
publically addressed device on the public internet has been updated to
support EzIP.  In addition, protocols such as DNS, SIP, and others which
pass around addresses will need to be updated to be able to pass the full
EzIP addressing around so endpoints can properly insert the EzIP header,
and so on.

The point I'm trying to make is that, at this point, deploying EzIP as an
end to end address exhaustion solution has MORE challenges that simply
deploying IPv6 would.  This is because, just like EzIP, deploying IPv6
requires a NAT box of some sort to be put in place until the last IPv4
device is turned off.   But unlike EzIP, almost every new device coming out
supports IPv6 out of the box.   All of the technical standards work has
already been done.   Thus, the only meaningful barrier to IPv6 at this
point is convincing people to use it, not convincing people to use it PLUS
convincing the tech companies to support it,  and doing protocol changes
like you would with EzIP.

I applaud your attempt at a unique solution but I really feel that ship
has sailed, at least for an EzIP type of solution. Maybe something like
this would have better received years ago, but at this point IPv6 is a much
more logical path forward.

I do wonder,  however,  if some of your concepts might be able to be
applied to the IPv6 transition.  I have some ideas here,  but most, if not
all, of them are only partially cooked but some have similar approaches as
EzIP but with an actual IPv6 packet inside.






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