The real DESCRIPTION field here is just the auto-generated stub "Cisco UCS fabric:FcSanEp:peerAggrPortId managed object property", so it carries no real prose -- but the property name and its Gauge32 type tell you what it holds: It holds the breakout sub-port index on the far end that this FC SAN uplink port is wired to, mirroring aggrPortId but describing the peer side of the connection. This lets UCS Manager record a full breakout-to-breakout mapping for the upstream Fibre Channel SAN switch port (an MDS or Nexus) it is cabled to, so a mis-cabled lane (say, local lane 1 patched to peer lane 3) shows up as a mismatch between this field and aggrPortId rather than as an unexplained link failure. If this FC SAN uplink port's local lane 1 connects straight across to lane 1 on the peer, this field reads 4; any other value would mean the lanes are crossed.