Cisco Catalyst 2960 Series User Manual

The following figure shows the network with Bridge Assurance enabled, and the STP topology progressing
normally with bidirectional BDPUs issuing from every STP network port.
Figure 31: Network with STP Topology Running Bridge Assurance
The following figure shows how the potential network problem shown in figure Network Loop Due to a
Malfunctioning Switch does not occur when you have Bridge Assurance enabled on your network.
Figure 32: Network Problem Averted with Bridge Assurance Enabled
The system generates syslog messages when a port is block and unblocked. The following sample output
shows the log that is generated for each of these states:
BRIDGE_ASSURANCE_BLOCK
Sep 17 09:48:16.249 PDT: %SPANTREE-2-BRIDGE_ASSURANCE_BLOCK: Bridge Assurance blocking port
GigabitEthernet1/0/1 on VLAN0001.
BRIDGE_ASSURANCE_UNBLOCK
Sep 17 09:48:58.426 PDT: %SPANTREE-2-BRIDGE_ASSURANCE_UNBLOCK: Bridge Assurance unblocking
port GigabitEthernet1/0/1 on VLAN0001.
Follow these guidelines when enabling Bridge Assurance:
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
301
Information About Optional Spanning-Tree Features

Cisco Catalyst 2960 Series Specifications

General

Layer	Layer 2
Power over Ethernet (PoE)	Available on some models
RAM	128 MB
Flash Memory	32 MB
MAC Address Table Size	8000
Operating Temperature	0°C to 45°C (32 to 113°F)
Ports	24 or 48 x 10/100/1000