Apart from anything else, even using fast ethernet and a switch rather than a router, there should be ample bandwidth to accommodate both the low bandwidth comms with the Mesa card and other stuff .. however as as you fire up linuxcnc, the other ethernet connectivity appears to disappear.
What I don't have is the patience to order multiple USB ethernet adaptors from Amazon and discover that they don't work in this combo. If someone could just point out one that is known to work, I'd really appreciate it. On Sun, 6 Mar 2022 at 22:47, Peter C. Wallace <p...@mesanet.com> wrote: > On Sun, 6 Mar 2022, Chris Albertson wrote: > > > Date: Sun, 6 Mar 2022 12:31:23 -0800 > > From: Chris Albertson <albertson.ch...@gmail.com> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <emc-users@lists.sourceforge.net> > > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net > > > > Subject: Re: [Emc-users] Pi4 with LinuxCNC and MESA 7i92H > > > > What is the actual goal? Keep anyone state it in exact terms? > > > > In past decades the Ethernet was a shared medium where every device was > > exposed to every packet sent by any other device. This was back in the > time > > when we used coaxial cables. Then twisted pair Ethernet was invented but > > we all used "hubs" that simply retransmitted any incoming packet to every > > other port. This simulated the way coaxial networks worked. Then > maybe > > 20 years ago? We started to use "Ethernet switches". These devices look > > at the packet header from each inbound packet on each port and only send > it > > out the port it is addressed to. So on a modern Ethernet, a device > like > > a Pi4 or MESA 7i92H never sees Ethernet packets that were not sent to it. > > OK, there are some broadcasts that are sent to every device. > > But simply using a modern switched Ethernet gets a LONG ways to an > > isolated network. My gues is the advice to use dedicated network > hardware > > comes from the era before network switches where common > > > > So again, what exactly is the goal? > > > > Maybe the goal is not to delay outbound traffic from the Pi4 to the MESA > > 7i92H? So if the Pi4 is sending data to some web server we do not > > want our web surfing to be queued ahead of the LCNC related commands. > > But do you get this effect by installing a second Ethernet port? I > doubt > > it. The only queue in the system is inside the Linux OS. > > > > It would be good to know EXACTLY what the problem is, > > > > > > The bottleneck with a shared Ethernet port is the MAC/Phy which would mean > outgoing and incoming real time packets might need to wait for normal > (large > packet) Internet traffic, adding considerable jitter. This is solved by > using a > separate physical interface. > > > Peter Wallace > Mesa Electronics > > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
