Cisco Catalyst 4500 Series - Page 782

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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 26 Configuring Optional STP Features
About Bridge Assurance
Figure 26-4 shows the network with Bridge Assurance enabled, and the STP topology progressing
normally with bidirectional BDPUs issuing from every STP network port. Figure 26-5 shows how the
potential network problem shown in Figure 26-3 does not occur when you have Bridge Assurance
enabled on your network.
Figure 26-4 Network with STP Topology Running Bridge Assurance
Figure 26-5 Network Problem Averted with Bridge Assurance Enabled
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)
Blocked
186526
Edge
Network
Network
Root
Network
Root
BPDUs
354161
Stopped receiving
BPDUs
Stopped receiving
BPDUs
Edge
Network
Network
Network
X