This string is the vendor identifier of the hardware component underlying this internal backplane link. It matters on the internal Ethernet link that carries a blade's traffic from the chassis I/O Module up to a Fabric Interconnect over the backplane because it confirms whether the installed component (e.g. a transceiver) is Cisco-qualified, which affects both support eligibility and, in some UCS firmware versions, whether the port will even come up. A vendor value that doesn't match Cisco on this backplane link is exactly the kind of finding that explains an otherwise unexplained 'unsupported transceiver' fault on that port.