4

The original SFP specification (INF-8074i) was intended for Ethernet and Fibre Channel use. While Ethernet used to increment speeds by a factor of ten, FC doubled the speed over generations. At the time of SFP introduction in 2001 those speeds where 1.25 and 4.25 Gbit/s raw, respectively. There is no support for 2.5 Gbit/s Ethernet because 2.5G is twisted-...


3

Cisco is being a bit literal. 10/100 "T" (twisted pair) does have independent TX and RX conductors. In a point-to-point situation, the link is fundamentally full-duplex. However, when a hub is involved, everyone's TX is connected to everyone else's RX. As a result, it's impossible for more than one node to transmit at a time, thus half-duplex, but ...


2

"does a crossover cable decrease power consumption, increase transfer speed, or decrease load on the adapter or other components?" No, not at all. The speed, power consumption, latency, etc. are all the same for a straight-through vs. a crossover cable. The bandwidth is the bandwidth. For 1000Base-T (1 Gbps on UTP) it is always 1 Gbps.


2

There's Auto Negotiation and that's it. Both sides advertise the speeds and modes they support and the best mutual mode is chosen. The cable is not tested. If the cable quality doesn't support the chosen speed, transmission errors and even repeated link loss have to be expected. The rare exception are "smart-rate" ports for 2.5/5 Gbit/s (and often ...


1

This configuration looks very much like a Cisco IOS configuration. You could try using the global spanning-tree portfast default global command. It only affects access interfaces, not trunk interfaces. Or, you could try the #spanning-tree portfast interface command for a specific access interface. Portfast bypasses the STP blocking, listening, and learning ...


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