On 2020-05-28 08:30 AM, Alvin Starr via talk wrote:
Generally speaking fiber is still more expensive than copper wiring
but 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.
The cost of fibre patch cords isn't that far from copper:
https://www.fs.com/c/fiber-optic-cables-209?gclid=Cj0KCQjwwr32BRD4ARIsAAJNf_1q8st39oVuCo89F6NQOX8dAx0yCm8-isqGkMAxY3_IgfIIJgQsaWsaAm7cEALw_wcB
SFP modules will set you back less than $10. Compare that to the cost
of a Cisco switch or router and you'll find the difference is trivial.
There's also the advantages such as immunity from electrical
interference, shock hazard, no longer limited to 100M (in fact, it's
possible to cross the Atlantic, without repeaters). Unbelievable
bandwidth (theoretical maximum 2.5 petabit, IIRC), less volume
(important with larger cables) and more.
Redundant networks over the same cable(bundle) is not really redundant.
Who said anything about being in the same bundle?
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.
Token ring was deterministic, in that there was a maximum time, before a
device could transmit. This compared with half duplex Ethernet (coax or
hub), where there's a random factor. However, that difference doesn't
exist with switches, where you can assign priority, scheduling and
more. The limiting factor with Ethernet is something called
"funneling", where packets from multiple sources are all heading to the
same port, which will cause a backup. VLAN tags can be used to provide
priority, as well as ToS in IP. So, it all boils down to proper
engineering of the network.
Throwing out real-time response and using CSMA/CD half duplex
operation made the initial Ethernet hardware much cheaper than its
competitors.
When's the last time you saw half duplex Ethernet? Also, most of that
gear ran at 10 Mb, with a small amount capable of 100 Mb. However,
switches killed half duplex. Of course, 100 Mb was left in the dust
years ago, with 100 Gb, or more, now used in many applications.
https://en.wikipedia.org/wiki/Terabit_Ethernet
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.
IP and Ethernet are best effort. Then again, so was token ring. They
all rely on some end to end protocol, such as TCP to provide protection
against data loss. You'd have to go back to X.25 (yes, I've worked with
that too) to get such protection on a per hop basis.
As I mentioned, almost my entire career, going back to 1972 has been in
telecom, computers and networks, so I do have some idea about what I'm
talking about.
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