Can I connect a 25Gbps QSFP28 port to a 10Gbps SFP+ port using either fiber or copper?
I'm building out a network with some high speed interconnects coupled to a slower gigabit network. On the high speed side, I plan to have several servers that will be connected to a Mellanox MSN2700 (or similar) which is QSFP28. These will be running at 25Gbps over fiber. On the low speed side, we'll have a couple 1Gbps switches with a few dozen clients, with 10Gbps ports bridging them to the Mellanox switch. Most 1/10Gbps switches I've seen use SFP+ connectors for the 10Gb lines.
I've looked and I've found adapters for QSFP28-SFP28, QSFP-SFP, QSFP+-SFP+, and others. I assume that some of these are physically identical (possibly QSFP, QSFP+, and QSFP28, and SFP variants perhaps?) but I'm not sure which ones are protocol compatible, i.e. if I have a QSFP28 fiber transciever on one end and a SFP+ fiber transciever on the other, will that work?
Any help would be appreciated.