Mellanox is an independent manufacturer of switch ASICs and switches. They also make PCI network adapter cards and infinband and direct attach cables. They are the goto company for Infiniband. They have branched into Ethernet and Fiberchannel. The company positions itself as a scrappy innovative alternative to Broadcom. Their pitch: while Broadcom may be first to put out a press release, Mellanox routinely beats them in getting products out the door.
Mellanox is an Isreali company with an office in Sunnyvale.