Re: Backward Compatibility Re: 202401100645.AYC Re: IPv4 address block

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

Hi, Christopher"

1)    "  IPv6 is designed to replace IPv4.  ":

    Correct. But, this is not like Ten Commandments that God gave to 
his children. Even such had not worked out in most cases. In real life, 
technical backward compatibility is the only known approach to achieve 
graceful replacement of the old. Failing to observe such discipline, one 
should not blame others for the disappointment in the transition. I am 
an outsider to the Internet development history. But, the overall 
appearance at this moment is that somehow IPv6 design failed to properly 
execute the backward compatibility requirement. So, IPv6 replacing IPv4 
is not given.

2)    Allow me to share with you an almost parallel event in the PSTN, 
to illustrate how tough is to achieve the replacement of a working 
service, even under an environment with very strict backward 
compatibility disicpline:

    A.    The Decadic (rotary) Dialing (DD) technique worked well on 
the telephone loop to a certain limit of distance for many years that 
enabled the automatic telephone switching systems. But, it could not go 
beyond the CO (Central Office).

    B.    So, Bell Labs studied the use of DTMF (Dual Tone 
Multi-Frequency) or commonly known as Touch-Tone as trademarked in US, 
etc. The work started in mid 1940s.

    c.    By late 1960s, working demos became available. During the 
mid-1970s, it was deployed across the Bell System (and beyond upon 
requests from other countries).

    D.    With end-to-end signally capability of the DTMF signalling, a 
lot of services such as remote purchase, airline status checking , 
etc.,grew drastically.

    E.    However, DTMF was a complete technology from Decadic Dialing 
and most phones in the field were still the latter type. COs had to 
install dual function line cards on the loop that subscriber liked to 
enjoy the DTMF capability. Obviously, the dual function line cards 
costed more than that of the basic DD version.

    F.    Initially, AT&T offered the DTMF service for free (well, 
covered by the rental of the new phone) to encourage that adoption. 
Then, they raised the monthly service rate for lines still requiring DD 
receiver hoping to gracefully forcing the subscribes to wean from using 
DD phones.

    G.    Guess what, the inertia of the huge DD phones out there in 
the field accumulated through near one century made the strategy 
impossible. That is, many subscribers would rather to pay one extra 
dollar or so a month to enjoy having the old DD phone around, either to 
avoid paying a new DTMF phone or just for the antique look of the DD 
phone. This also created a nightmare of three types (DD, DTMF and 
combined) line cards in the CO.

    H.    As this went on, a version of phone with DTMF dial pad but 
sending out DD pulses appeared on the open market (thanks to the 
deregulation / break up the Bell System). Such novelty phones really 
gave phone companies a hard time about the transition plan.

    I.    In the meantime, IC technology advanced to have single chip 
capable of both dialing techniques (even further integrated other 
traditional line card functions onto the same chip) making the 
transition plan moot.

    J    Nowadays, almost every line card type chip handles DTMF as 
advertised. But, if you try a DD phone on it, chances are, it works anyway!

    K. You may see some parallelism between the above and the current 
IPv4 / IPv6 transition issues.


Regards,


Abe (2024-01-15 12:37)




On 2024-01-15 00:15, Christopher Hawker wrote:
> To my knowledge IPv6 is designed to replace IPv4. Anyone, feel free to 
> correct me if I'm wrong. There are just short of 4.3 billion IPv4 
> addresses, where the number of IPv6 addresses is 39 digits long.
>
> Regards,
> Christopher Hawker
>
> On Mon, 15 Jan 2024 at 15:18, Abraham Y. Chen <aychen () avinta com> wrote:
>
>     Hi, Randy:
>
>     1)   " ... unfortunately i already had grey hair in the '90s and
>     was in the room for all this, ...  ":
>
>         My apologies! For an uninitiated, I misread your message as if
>     IPv6 was originally designed with a plan to assure smooth
>     transition from IPv4.
>
>     Regards,
>
>
>     Abe (2024-01-14 23:17)
>
>
>     On 2024-01-12 17:45, Randy Bush wrote:
> > >     Perhaps you are too young to realize that the original IPv6 plan was
> > >     not designed to be backward compatible to IPv4, and Dual-Stack was
> > >     developed (through some iterations) to bridge the transition between
> > >     IPv4 and IPv6? You may want to spend a few moments to read some
> > >     history on this.
> >     ROFL!!!  if there is anything you can do to make me that young, you
> >     could have a very lucrative career outside of the internet.
> >
> >     hint: unfortunately i already had grey hair in the '90s and was in the
> >     room for all this, and spent a few decades managing to get some of the
> >     worst stupidities (TLA, NLA, ...) pulled out of the spec.  at iij, we
> >     rolled ipv6 on the backbone in 1997.
> >
> >     randy
>
>
>
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