[Beowulf] How to know if infiniband network works?

[Faraz Hussain]

I have inherited a 20-node cluster that supposedly has an infiniband  
network. I am testing some mpi applications and am seeing no  
performance improvement with multiple nodes. So I am wondering if the  
Infiband network even works?

The output of ifconfig -a shows an ib0 and ib1 network. I ran ethtools  
ib0 and it shows:

         Speed: 40000Mb/s
         Link detected: no

and for ib1 it show:

         Speed: 10000Mb/s
         Link detected: no

I am assuming this means it is down? Any idea how to debug further and  
restart it?

Thanks!