xSTP Syslog for BPDU Threshold

The xSTP syslog messages for BPDUs are created when CPU utilization is more than the ISSU threshold value and also, when the system receives more than a certain amount of xSTP BPDUs.

If the received xSTP BPDU count goes higher than a threshold value and also, if the CPU utilization is higher, we will log the syslog. Later, when this condition gets cleared, another syslog message is generated. These syslog messages are not generated immediately after the control bridge is UP. The system will wait for some time to reach the steady state before creating the syslog.

Syslog messages for xSTP are logged into the system to inform that the CPU utilization rate is higher than the normal value and the BPDU processing rate for a minute is higher than the threshold limit. Scalability can be a challenge for Campus Fabric (SPX) system having thousands of ports. Syslog messages are generated depending upon the received STP or PVST BPDUs. If the CPU utilization exceeds a threshold value, ISSU cannot be performed on a Campus Fabric (SPX system. Even if xSTP is not enabled, the system may still receive xSTP BPDUs and these BPDUs are forwarded to other ports in the system.

Syslog messages are also created when a switch gets connected to Campus Fabric (SPX) system through a Port Extender. If the BPDU received from a switch has a Bridge ID that belongs to another switch, a syslog is created to indicate the presence of a switch on the Port Extender port. Also, if no other BPDU messages are received within the next minute, a corresponding clear syslog will be generated. Based on the Campus Fabric (SPX) scale setup, the high threshold value is 1000 BPDUs per second and the low threshold will be 10% less than the high threshold. But, if the low threshold is reached, a clear condition syslog is created. The xSTP syslog messages will be logged in again if the high threshold and the CPU rate condition reappears. The following are some of the examples of syslog messages.

The syslog message for BPDU threshold crossing and clearing looks like the following:

SYSLOG: <#> xSTP BPDU Threshold (1000 pps) reached

The following syslog is created when the condition gets cleared

SYSLOG: <#> xSTP BPDU Threshold condition cleared

When a switch gets detected on the port extender port:

SYSLOG: <#> External Switch detected on PE User Port

The following syslog is created when the condition gets cleared

SYSLOG: <#> No External Switch detected on any PE User Port

SYSLOG: <#> xSTP BPDU Threshold (1000 pps) reached

The clear syslog message is:

SYSLOG: <#> xSTP BPDU Threshold condition cleared