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Author: Jim Jackson
Date:  
To: Dng
Subject: Re: [DNG] Request for information - - re: networking



On Mon, 5 Jun 2023, o1bigtenor via Dng wrote:

> On Mon, Jun 5, 2023 at 1:38?PM Antony Stone
> <Antony.Stone@???> wrote:
> >
> > On Monday 05 June 2023 at 20:30:19, Jim Jackson wrote:
> >
> > > On Sun, 4 Jun 2023, o1bigtenor via Dng wrote:
> > > > Should I switch my present router from 192.168.1.1 to my chosen
> > > > 172.16.x.x (I'm running on dd-wrt)?
> > >
> > > Do you want your sensors (assumed ethernet connected) to use the router and
> > > be able to access / be accessed from the internet?
> > >
> > > If yes then do it.
> >
> > Why do you recommend changing to 172.16.0.0/16 instead of using
> > 192.168.0.0/16?


Security - the router doesn't need changing and doesn't know about the
new net and so can't forward traffic to it.

> > >     How are existing machines network configured?

> > >
> > >       If they are manually configured you will have give them numbers in
> > >       the new network range. If you let your router do DHCP, then you
> > >       should be ok.

> > >
> > >       How are the sensors network configured? If using DHCP, can your DHCP
> > >       server manage that numbers of DHCP clients? You may have to configure
> > >       your routers DHCP server to have a big enough range of addresses to
> > >       hand out.

> >
> > I think that should be trivial compared to the requirements for switches
> > and/or wireless access points to handle this many devices & addresses.


Some of the cheap-ish 24 port dumb switches manage 8k MAC addtress tables.
16 port 100 only 2k mac address table might cause a problem.

> > > If no then it would be better to use the existing 192.168.1.0 network for
> > > those machines that need internet access, and use the bigger 172.16.x.x
> > > addresses for the sensors and the machine they talk to.
> >
> > I don't see the advantage of over-complicating things in this way.
> >
> > > You can run several networks on the same phyical LAN. You will have to put
> > > the machine the sensors talk to on this network as well. A linux network
> > > interface has have several addresses.
> >
> Did some digging earlier today - - - switches - - - 10+1 and 16+1 are
> sorta cheap but not as
> cheap as the 16 port switches. What I found fascinating was that 48+2
> (or maybe 4) port
> switches are say $500 yet the 24+1 port switches are just over a $100
> - - - - makes sense
> at this point to have 24+1 port switches.


At the sorts of data rates you've quoted, 100M links between switches will
be fine even using 24 port switches.

> (Why 24+1 port switches - - - individual sensors + most other things on the lan
> function just fine at 100 MBit/sec (if not even lower) - - then
> collecting the 24 ports
> together and sending to 'management/oversight' at I GBit/sec.)
>
> Thanking all the contributors for my education upgrade - - - (grin!).
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