I think I already know the answer to this, but will ask anyway. CCR2004-1G-2XS-PCIe is a really affordable 25Gig “NIC” coming in at around half the cost of some others. Would be awesome to include in a system for hyper convergence, but does it support any form of RDMA? I cannot find any information on this.
Thanks!
It does not support any kind of RDMA.
I think the best use case for the CCR2004-1G-2XS-PCIe in a hyperconverged infrastructure is to form a network fabric between nodes and offload the VXLAN/eVPN functionality. Or to provide a L3 firewall in front of the Hypervisor node.
Not with L2 (IB/RoCE) but L3 (iWARP) would probably work fine.
Probably the wrong choise for general storage network and such things.
All of this right here ^^^^^
EVPN all the things 
When it comes to combined compute and storage nodes which is the most common implementation of hyper convergence it will work fine using L3. Hyper convergence of pure storage networks usually requires tailor made L2 switches using asics for minimum latency and maximum throughput and to achieve full wire speed through all ports simultaneously.
Forgot to mention that besides to iWARP (TCP), RoCEv2 (UDP) works just as well on L3. If CCR2004-1G-2XS-PCIe is able to perform L3 HW offloading for RoCEv2, it would be suitable also for a storage cluster.
Not sure what adjustments it takes to get L2 RoCEv1 (type 0x8915) get routed using 9K jumbo frames. I’ll send an inquiry to the guys at STH if they might investigate the matter.