You will need a device that bridges the ethernet to infiniband. The switches you link do not have that ability but IF your infiniband switches have 10g ethernet ports then they will do that. They do make standalone bridge devices but it is more common to buy this as a option in your infiniband switch since it lets it use the backplane rather than having to buy lots of interfaces to cross connect all this stuff.
get very complex when you want to retain your redundancy. I would suspect you could build your own but I have never done it. Most the time when I get involved with stuff like this performance is key and money doesn't matter so they just buy the proper switches.
I know the last one we put in the servers had 2 connection 1 to the ethernet to talk to users and a second to the infiniband to access the storage. In this case the users did not directly access the data they issued transactions to the server.
You may want to try to post this to the server forum maybe someone else has a better soltuion.
I actually work in the IB business, and I can tell you that our bridge (4036E) brand new isn't cheap for a small home use cluster. But, I've had customers that have built their own `routers` using Linux using stuff like iptables. You can drop me a note if you want to discuss further.