On 2020-05-27 04:26 PM, Russell Reiter wrote:
I can't say for sure whether token ring on optical networks has left the IoT entirely.
There have been a lot of technology that's come and gone over the years.
Fiber and associated hardware is still very expensive.
Not really. Generally speaking fiber is still more expensive than copper wiring but
On 5/28/20 6:57 AM, James Knott via talk wrote: the difference is not nearly as bad as it once was. The biggest thing is the price of CAT-5,6,7... is way down the price curve due to volume and the fact that most of us can afford the hardware to terminate copper cable. The cost of fiber termination is still way up there.
In some process and control systems redundancy and fail-over take necessary priority
Yep, and there are ways to do that with Ethernet and IP. I mentioned the 432 fibre strands on the Finch LRT. That's split into 2 redundant networks.
Redundant networks over the same cable(bundle) is not really redundant. Ethernet is not a real-time protocol. There are a number of ways to cover that shortcoming but Ethernet networks will never have deterministic throughput. For most things this is OK but if you need microsecond level timing then your looking at some other protocol. Throwing out real-time response and using CSMA/CD half duplex operation made the initial Ethernet hardware much cheaper than its competitors. With that market share the incremental changes to the hardware have made the original Ethernet unrecognizable. As for IP. It is best described as resilient and not redundant. The protocols on top of IP make for a very robust network that will generally route around failures. But they are even further from deterministic. -- Alvin Starr || land: (647)478-6285 Netvel Inc. || Cell: (416)806-0133 alvin@netvel.net ||