Can 10Gb SFP+ run 2.5Gb given that my traffic source is scaled down from 10Gb to 2.5Gb?
Yes. This will work just fine, provided that both sides of the connection are physically 10GbE.
Now, why will this work?
It’s because what we’re concerned with is not the data rate itself, but what the physical layer is. In this case, so long as both ends are physically 10GbE (and of course the same optical standard as well), then communication can occur, as both ends are, in essence, speaking the same language.
Contrariwise, let’s say we have a fiber link that’s physically 10GbE, but shaped down to 1GbE. Even though the link is only allowed to run at 1Gbps, if you were to use a gigabit optic on the other end, there would be no link and no communications, as the GbE and 10GbE specifications are quite substantially different and have no interoperability mode.
Thanks for the question!
In our monthly Ask Me Anything feature, our engineering team answers questions sent to firstname.lastname@example.org. Submit your queries and next month's topic could be yours!