The real DESCRIPTION field here is just the auto-generated stub "Cisco UCS fabric:FcVsanPortEp:peerSlotId 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 slot number on the far end of this VSAN port endpoint's connection, when the peer device is organized into slots. This is only meaningful when the far end is itself a modular device (like another switch with line cards); for this VSAN port endpoint, it fills out the physical address of the SAN switch port on the other end of that VSAN link alongside peerPortId. This VSAN port endpoint might report peerSlotId 2 if the SAN switch it connects to has a modular chassis with that many line-card slots.