We're purchasing new servers that have Mellanox ConnectX 6 network cards in them, which accept QSFP56 transceivers. The card says it supports 10/25/40/50/100/200G. However, our switching backbone is all 10G with SFP+ transceivers.
If I put a 40G transceiver in the card, can I directly connect that, 1:1, to the 10G transceivers in my Cisco 4500X switches, and the 40G transceiver will be able to run at 10G? Or, do I need to get a QSFP to SFP adapter and put SFPs in the Mellanox cards? I'd rather just buy 40G transceivers, now, if possible, and be able to use them when we eventually upgrade the switching backbone, rather than buying 10G transceivers and adapters, and then buying 40G transceivers later.
I'm aware of the existence of breakout cables, but I don't have enough ports for that, and we really don't want to buy a new switch if we can avoid it.
New switches are in the cards, but not for a couple more quarters, at least, due to budgets.