I got CSS610-8G-2S+IN switch recently for the fact that it comes with 2 x SFP+ ports (along with 8 x 1G ports). With a 10Gbe SFP+ transceiver connected to a 10G uplink, I assumed that all 8 x 1G ports would be able to switch at full 1G speed to any servers upstream. But iperf3 test I did suggests that the 8 x 1G ports seem to be bottlenecked at maximum 1G through the 10G SFP+ uplink.. meaning the 8 x 1G ports is sharing a 1G backplane (not sure if that's the right term).
Is that correct?? I hope not, because I don't see what's the purpose of those 2 x SFP+ port, if those 8 x 1Gbe ports cannot switch at full speed through the 10Gbe SFP+ port.