Cisco Catalyst 4500 Series Software Configuration Manual page 782

About Bridge Assurance
Figure 26-4
normally with bidirectional BDPUs issuing from every STP network port.
potential network problem shown in
enabled on your network.
Figure 26-4
Root
Network
Figure 26-5
Stopped receiving
Root
The system generates syslog messages when a port is block or unblocked. The following sample outputs
show the log that is generated for each of these states:
Blocked port:
Sep 17 09:48:16.249 PDT: %SPANTREE-2-BRIDGE_ASSURANCE_BLOCK: Bridge Assurance blocking
port GigabitEthernet5/8 on VLAN0200. (stack-dut-R4-4)
Unblocked Port:
Sep 17 09:48:58.426 PDT: %SPANTREE-2-BRIDGE_ASSURANCE_UNBLOCK: Bridge Assurance
unblocking port GigabitEthernet5/8 on VLAN0200. (stack-dut-R4-4)
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
26-12
shows the network with Bridge Assurance enabled, and the STP topology progressing
Network with STP Topology Running Bridge Assurance
Network
Network
Blocked
Edge
Network Problem Averted with Bridge Assurance Enabled
BPDUs
Network
BPDUs
Network
Edge
Figure 26-3 does not occur when you have Bridge Assurance
X
Network
Stopped receiving
BPDUs
Chapter 26 Configuring Optional STP Features
Figure 26-5 shows how the