Cisco. LOOPGUARD. Traffic limited.

In our case, a symptom that our Cisco Swich has reached the limit of its traffic management capacity at moment in  time is the  "LOOPGUAR_BLOCK" and "LOOPGUAR_BLOCK" alerts

At Switch

At Syslog

We can reproduce this problem when we move/copy big information amount. Example move Virtual Machines, Backup, etc.

A few of Literature:

"LoopGuard prevents alternateor root port from becoming designated in absence of BPDUs."

"Protects alternate (blocked) or root (forwarding) ports from moving to forwarding upon no receipt of BPDU’s."

"If a Port Receive state machine receives an inferior RST BPDU from a Port that believes itself to be a Designated Port AND is Learning or Forwarding it will set disputed, causing this state machine to transition a Designated Port to Discarding"

by GoN | Published: March 24, 2017 | Last Updated: