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We are planning to use Ethernet bus topology (wiki). The reason using this very old topology is hardware limitations and software requirements. Collisions should be OK, as bandwitdh requirement is very low.

My problem is, how can we test this topology with modern Ethernet controllers and software like Ubuntu etc. I could not find a good implementation example.

I have tried connecting three Intel Ethernet controllers (with Static IPs) together and only two of them had link at a time (they worked in point-to-point connection as usual)

ubsahin
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  • Did you use T connectors and the correct terminators, and what does this have to do with programming? – Ron Maupin Oct 26 '17 at 12:52
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    You need to tell us what kinds of hardware you have available (types of NICs, hubs, switches) and what hardware limitations and software requirements you're facing. – Zac67 Oct 29 '17 at 14:46
  • Well, hardware limitation is this: it is actually several custom PCBs connected via backplane. Backplane is a COTS product and has its slots pin-to-pin connected. Therefore we need to use some kind of bus topology. Additionally software team requires network interface so their previous designs can be reused. So we have chosen Ethernet-bus topology. – ubsahin Oct 30 '17 at 07:53
  • @RonMaupin It is not directly programming but I thought it could be related with setting up driver? I forgot to add terminations, I will try again. However, it already works between two nodes (any combination of 2 out of 3). Since distance is very short, I believe loss is not huge and currently it is working under poor conditions. – ubsahin Oct 30 '17 at 08:03

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"Modern" hardware is rather limited when trying to build a bus topology - it's much easier to build a more usual star/tree network. However, with the right key components you can even connect both topologies.

From the software point of view, the network just "works", i.e. as long as the network is configured correctly the software applications can (and should) be oblivious to the network layout.

With an assumed Ethernet network, the logical structure of each segment is a bus anyway: each device can just talk to any other device, regardless of where and how they are connected.

Zac67
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