Cisco Switch: Unexpected BPDU
received. Port has been Disabled
Cisco switch logs this message: Description: Gi3/0/15:
Unexpected BPDU received. Port has been Disabled. Based on
feature was first implemented to handle special collision
situations in which the switch detected excessive or late
collisions on a port. Excessive collisions occur when a frame is
dropped because the switch encounters 16 collisions in a row”.
Case 1: The
cable is defective. Replacing the cable works fine.
Case 2: The NIC has an issue. Upgrading the the driver fixes the
Case 3: It is port duplex mis-configuration.Based on Cisco: “A
port duplex misconfiguration is a common cause of the errors
because of failures to negotiate the speed and duplex properly
between two directly connected devices (for example, a NIC that
connects to a switch). Only half-duplex connections should ever
have collisions in a LAN. Because of the carrier sense multiple
access (CSMA) nature of Ethernet, collisions are normal for half
duplex, as long as the collisions do not exceed a small
percentage of traffic”.
The following lists could be the issue too.
Port channel misconfiguration
BPDU guard violation
UniDirectional Link Detection (UDLD) condition
Port Aggregation Protocol (PAgP) flap
Layer 2 Tunneling Protocol (L2TP) guard
DHCP snooping rate-limit
Incorrect GBIC / Small Form-Factor Pluggable (SFP) module or
Address Resolution Protocol (ARP) inspection
detection is enabled for all of these reasons by default. In
order to disable error-disable detection, use the no
errdisable detect cause command. The show errdisable
detect command displays the error-disable detection status.
More case can be
found here: Unexpected BPDU received.
Port has been Disabled
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