I see 10G SFP+ modules (RJ45 port) popping up claiming to be able to also run 1G and foremost 2.5G/5G (NBASE-T).
What if the switch itself only refers to the following standards?
- IEEE 802.3ab 1000BASE-T
- IEEE 802.3z 1000BASE-X
- IEEE 802.3ae 10GBASE-X
- IEEE 802.3ba 40GBASE-X
Will it be able to use 2.5G with such an SFP+ module?
What does this depend on? Does it depend on the PHY?
On a copper port-only switch the PHY is probably located inside the switch. In an SFP-based switch the PHY is located inside the SFP module I guess.
So why does it depend on the switch? (Especially in the above example where the maximum port speed is 40Gbps, why wouldn't it support 2.5G?)
I found a guy who claims that using a third party 10/5/2.5/1GBASE SFP+ module, his Netgear switch which is not specified for 802.3bz now does exactly that.