NVIDIA® WHAT JUST HAPPENED®is based on the extended telemetry capabilities of the NVIDIA Spectrum family switches. This feature, enabled by default, provides the ability to retain the last packets that were dropped from the switch with complete packet headers and the actual drop reason. This enhances the ability to debug network problems, identify affected flows, and decrease time-to-repair.
Retrieving WJH information is done by specifically requesting the last N (up to max 1024 packets per drop reason group) dropped packets & their respective drop reasons. The information is displayed with important Ethernet, IP, and L4 headers. For complete packets, a pcap file is available.
WJH also provides aggregation record for respective drop reasons.
There are four major interfaces enabling the usage of:
NVIDIA Onyx CLI
NVIDIA Onyx Web UI
NEO
TIG Stack
The following chapters will explain how to use WJH in each of the above modes.
WJH is only supported through CLI, WebUI, or using NEO, but not in parallel.