[CentOS] Centos 7: UPD packet checksum verification?

Wed Jan 29 14:44:11 UTC 2020
Stephen John Smoogen <smooge at gmail.com>

On Wed, 29 Jan 2020 at 08:16, hw <hw at gc-24.de> wrote:
> On Wednesday, January 29, 2020 12:38:32 AM CET Stephen John Smoogen wrote:
> > On Tue, 28 Jan 2020 at 15:56, hw <hw at gc-24.de> wrote:
> > > > For voice, that
> > > > usually means a drop or other ugliness because it is assumed that if
> > > > the quality is too bad, the people would just call each other again.
> > >
> > > That's a funny idea.  Phone calls just worked fine and were good quality
> > > 25
> > > years ago, and mostly long before that.  I have never expected to have to
> > > call anyone back because of poor quality in over 40 years, and I'm not
> > > going to start to expect that now.
> >
> > I got that from watching various training videos from the 1940's to
> > the 1970's on phone switching systems... and also the basic design of
> > how Erlang is programmed and deals with errors. It could be wrong,
> > erroneous or crap. However talking to phone people over the years that
> > was how they described things. A lot of them would say that a phone
> > call could die a billion different ways and it was a miracle it didn't
> > happen to everyone every day. It just happened to a couple of people a
> > day in different places because everything was coded for redundancy
> > and the expectation that it could get bad. That redundancy and
> > over-engineering seems to have allowed for the 'worse case they will
> > call back' to be a viable option.
> Maybe it took a lot of effort to keep things working, I can't tell.  But I can
> tell that for over 40 years, there was one single interruption of the phone
> line when a major line was damaged due to construction work.  Calls weren't
> interrupted, either.

40 years ago if you were in North America or Europe you were relying
on large infrastructure laid out by 'Cold War' needs that if a war
started the phones from site A to site B would work no matter what.
That meant there were all kinds of redundancy in the system.. enough
that pretty much every Phone company whether national or private were
valued by the amount of copper they had mostly from all this
redundancy. When that was no longer a driving factor and various
governments were no longer enforcing 'war' regulations on how the
phones MUST work.. you saw a lot of lines removed and the copper sold
as cash from both private and public phone companies. This was part of
the 'peace' dividend that many countries saw in the 1990's where
various other infrastructure could be upgraded because it wasn't being
held in reserve in case of war. The improvements in mobile phone
networks increased this because phone quality was limited to the
codecs used in that and you didn't need to string as much copper and
could even move to lower quality copper. Optical fibre also got
cheaper which allowed for improvements and more dumping of old copper
lines. The problem is that phone companies over-dumped and the prices
of copper have gone up enough that they can't adequately replace what
they need to do now. So they are pushing for more VOIP like solutions
to keep their costs down.. but

These things go in cycles.. and usually you have to go through a
'everything has gone to hell' before people wake up and realize they
needed to invest a certain amount in the infrastructure constantly. So
hopefully it will get better someday...

Stephen J Smoogen.