Sometimes, when one updates the firmware for Mellanox Infiniband cards, the MAC/hardware address gets changed. This usually happens if the IB card is OEM, i.e. made by Mellanox but stamped with a different company's name.
When the MAC gets changed, the network interface will not come up. The fix is to update the HWADDR field in /etc/sysconfig/network-scripts/ifcfg-ib0 and /etc/sysconfig/network-scripts/ifcfg-ib1. Use "ip link list" to display the new MAC.