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Catalyst 3750, 3560, 3550, 2975, 2970, and 2960 Switch System Message Guide
OL-8551-04
Chapter 3 Message and Recovery Procedures
SPANTREE Messages
Error Message SPANTREE-2-ROOTGUARD_BLOCK: Root guard blocking port [chars] on
[chars].
Explanation On the listed interface, a BPDU was received that advertises a superior spanning-tree
root bridge (lower bridge ID, lower path cost, and so forth) than that in use. The interface is put into
blocking state and marked as root-guard inconsistent to prevent a suboptimal spanning-tree
topology from forming. The first [chars] is the port name, and the seco nd [chars] is the spanning-tree
mode displayed in the output of the show spanning-tree privileged EXEC command.
Recommended Action Enter the show spanning-tree inconsistentports privileged EXEC command
to review the list of interfaces with root-guard inconsistencies. Find out why devices con nected to
the listed ports are sending BPDUs with a superior root bridge, and take action to prevent more
occurrences. When the inaccurate BPDUs have been stopped, the interfaces automatically recover
and resume normal operation. Make sure that it is appropriate to have root guard enabled on the
interface.
Error Message SPANTREE-2-ROOTGUARD_CONFIG_CHANGE: Root guard [chars] on port [chars]
on [chars].
Explanation The spanning-tree root guard configuration for the listed interface has change d. If
enabled, any BPDU received on this interface that advertises a superior spanning-tree root bridge
(lower bridge ID, lower path cost, and so forth) to that already in use causes the interface to be put
into the blocking state and marked as root-guard inconsistent. The first [chars] is the root-guard state
(enable or disable), the second [chars] is the interface, and the third [chars] is the spanning-tree
instance.
Recommended Action Verify that this is the desired configuration for the listed interface. Correct it if
it is not the desired configuration; otherwise, no action is required.
Error Message SPANTREE-2-ROOTGUARD_UNBLOCK: Root guard unblocking port [chars] on
[chars].
Explanation The listed interface is no longer receiving BPDUs ad vertising a superior root bridge
(lower bridge ID, lower path cost, and so forth). The root-guard inconsistency is cleared for the
interface, and the blocking state is removed from the interface. The first [chars] is the port name,
and the second [chars] is the spanning-tree mode displayed in show spanning-tree privileged EXEC
command.
Recommended Action No action is required.
Error Message SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking [chars] on [chars]. Port
consistency restored.
Explanation The port VLAN ID or port type inconsistencies have been resolved, and spanning tree
will unblock the listed interface of the listed spanning-tree instance as appropriate. The first [chars]
is the interface, and the second [chars] is the spanning-tree instance.
Recommended Action No action is required.