Cisco 3845 Message Guide - Page 73

Chapter 2 Messages and Recovery Procedures SPANTREE Messages feature is mainly used to detect unidirectional links. The first [chars] is the loopguard state (enable or disable), the second [chars] is the interface name, 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 this is not the desired configuration. Error Message SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port [chars] on [chars]. Explanation The listed interface has received a BPDU. If the inconsistency was caused by a unidirectional link failure, the problem no longer exists. The loopguard-inconsistency is cleared for the interface, which is taken out of the blocking state, if appropriate. The first [chars] is the port name, and the second [chars] is the spanning-tree mode displayed in the show spanning-tree privileged EXEC command. Recommended Action No action is required. Error Message SPANTREE-2-PVSTSIM_FAIL: Superior PVST BPDU received on VLAN [dec] port [chars], claiming root [dec]:[enet]. Invoking root guard to block the port. Explanation Root guard blocked a port that might cause a spanning-tree loop. When a PVST+ switch is connected to an Multiple Spanning Tree (MST) switch, the Internal Spanning Tree (IST) root (MSTOO) becomes the root for all PVST+ spanning trees. A loop can occur if any of the PVST+ spanning trees have a better root than IST. To prevent the loop, root guard blocks the port on the MST switch that receives the superior message from the PVST+ side. The first [dec] is the VLAN ID, [chars] is the short interface name, such as Gi0/1, the second [dec] is the root bridge priority, and [enet] is the root bridge MAC address. Recommended Action When spanning tree converges after a new switch or switch port is added to the topology, root guard might temporarily block the port and then automatically restore it. If the port remains blocked, identify the root bridge from this error message, and configure a less favorable priority for the VLAN spanning tree. There could be other superior PVST roots, and the port cannot recover until all such roots are cleared. Alternatively, try disabling and then enabling the VLAN port. Error Message SPANTREE-2-RECV_1Q_NON_1QTRUNK: Received 802.1Q BPDU on non 802.1Q trunk [chars] [chars]. Explanation The interface that received a Shared Spanning Tree Protocol (SSTP) BPDU was in trunk mode but was not using 802.1Q encapsulation. The first [chars] is the interface, and the second [chars] is the VLAN. Recommended Action Verify that the configuration and operational state of the listed interface and that of the interface to which it is connected are in the same mode (access or trunk). If the mode is trunk, verify that both interfaces have the same encapsulation (none or 802.1Q). When the encapsulation is consistent, spanning tree automatically unblocks the interface. OL-23408-01 Cisco ME 3400E, ME 3400, and ME 2400 Ethernet Access Switch System Message Guide 2-59