outage-detection brownout

Specifies the parameters used by CNA for detecting network brownout conditions.

outage-detection brownout
 
        { enable | disable |
 
         absolute threshold <abs-rating> |
 
         relative { sample-period <seconds> | threshold <rel-rating> } |
 
         tolerance <tolerance> }
 
no outage-detection brownout
 
no outage-detection brownout absolute threshold
 
no outage-detection brownout tolerance
 
no outage-detection brownout relative threshold
 

 

Arguments

• abs-rating--decimal value in the range, 0.0 to 4.9
• rel-rating--decimal value in the range, 0.1 to 5.0
• time--sample period in seconds (60 through 86400)
• tolerance--decimal value in the range, 0.0 to 4.9

Must be in engine or policy configuration mode (config-engine or config-engine-policy), which requires privileged-level access.

Use once.

• abs-rating--3.0
• rel-rating--1.0
• time--14440 (4 hours)
• tolerance--0.1

NOTE: A network brownout, sometimes called a soft outage, occurs when there is a significant reduction in application performance to end users as a result of network problems such as congestion, packet loss, link or equipment failures, or configuration errors. Brownouts differ from blackouts (also known as hard outages) which occur when a network or portion of a network fails completely. Brownouts occur when connectivity theoretically still exists but excessive latency and loss make the network effectively unusable. Standard routing protocols only detect hard outages, so while blackouts can eventually be overcome, normal routing will not detect or correct a brownout, allowing the condition to persist.

CNA is able to detect and take corrective action for network brownouts. Use the outage-detection brownout command to change CNA’s sensitivity to network brownout conditions to suit the specific needs of your network. In order detect a brownout, CNA will establish the baseline performance of each prefix, ranging from 0.0 (worst) to 5.0 (best), over time. The relative threshold is subtracted from this value and compared to the absolute threshold. The lesser of these values yields the effective threshold, which is used to determine if there is a brownout condition. If the prefix is currently performing equal to or worse than this computed value minus the tolerance, then there is a brownout. The brownout condition ends when the current performance is better than the effective threshold plus the tolerance. Note that the tolerance parameter provides hysteresis for brownout transitions.

Use the relative sample-period keyword to change the time interval between each measurement used for calculating the baseline performance of a prefix.

Use the no form of the outage-detection brownout command to revert to the default settings.