Running ibdiagnet without command line parameters will perform the following fabric diagnostics:
Fabric Discovery
Duplicated GUIDs check
Duplicated Node Description Check
LID Check
Links Check
Subnet Managers Check
Port Counters Snapshot/Checks in One Sec Period
Nodes Information Check (Uniform firmware versions across the fabric. etc)
Speed/Width Check
Dump Virtualization Information
Partition Keys Checks
Dump Temperature Sensing
Create Network Dump File Similar to the ibnetdiscover Format