| Purpose |
This probe calculates ECMP imbalance on generic system-facing ports. The set
of external-facing links (keyed by common system_id) is determined to be
imbalanced if the standard deviation of the tx_bytes counter (averaged
periodically over the specified period) for the involved interfaces is above
"Max Standard Deviation". If such imbalance is observed for more than
"Threshold Duration" over the last "Duration" time period, an anomaly is
raised. The last "Anomaly History Count" anomaly state changes are stored
for observation. If more than "Max Imbalanced Systems" systems are
imbalanced,an anomaly is raised. We maintain for inspection the number of
imbalanced systems over the last "System Imbalance History Count"
samples.
When instantiating this probe, external router tag(s) must be specified.
|
| Source Processor |
| external interface traffic (Interface Counters) |
Purpose: wires in interface traffic samples (measured in
transmitted bytes per second) from each interface connected to
the generic systems.
Output Stage: external_int_traffic
|
|
| Additional Processor(s) |
| external interface traffic avg (Periodic Average) |
Purpose: Calculate average traffic during period specified by
average_period facade parameter. Unit is bytes per second.
Input Stage: external_int_traffic
| Output Stage: external_int_traffic_avg |
Set of traffic average values (for each generic
system-facing interface). Each set member has the
following keys to identify it: label (human-readable
name of the system), system_id (id of the system,
usually serial number), interface (name of the
interface).
|
|
| external interface std-dev (Standard Deviation) |
Purpose: calculate standard deviation for a set consisting of
traffic averages for each generic system-facing interface on a
given system. Grouping per system is achieved using 'group_by'
property set to 'system_id' and 'label'.
Input Stage: external_int_traffic_avg
| Output Stage: ext_int_std_dev |
Set of values, each indicating standard deviation (as
a measure of ECMP imbalance) for traffic averages
for each generic system-facing interface on a given
system. Each set member has 'system_id' and 'label'
key to identify system whose ECMP imbalance the
value represents.
|
|
| std-dev percentage (Ratio) |
Input Stage: ext_int_std_dev
Output Stage: std_dev_percentage
|
| live ecmp imbalance (Range) |
Purpose: Evaluate if standard deviation between generic
system-facing interfaces on each system is within acceptable
range. In this case acceptable range is between 0 and std_max
facade parameter (in bytes per second unit).
Input Stage: std_dev_percentage
| Output Stage: live_ecmp_imbalance |
Set of true/false values, each indicating if standard
deviation (as a measure of ECMP imbalance) for
traffic averages for each external router-facing
interface on a given leaf is within acceptable
range. Each set member has system_id key to identify
system whose ECMP imbalance the value
represents.
|
|
| links imbalanced percentage (Match Percentage) |
Input Stage: live_ecmp_imbalance
Output Stage: links_imbalanced_percentage
|
| systems imbalanced (Range) |
Input Stage: links_imbalanced_percentage
Output Stage: systems_imbalanced
|
| sustained ecmp imbalance (Time in State) |
Purpose: Evaluate if standard deviation between generic
system-facing interfaces on each leaf has been outside
acceptable range, (as defined by 'live ecmp imbalance'
processor) for more than 'threshold_duration' seconds during
last 'total_duration' seconds. These two parameters are part of
facade specification.
Input Stage: systems_imbalanced
| Output Stage: sustained_ecmp_imbalance |
Set of true/false values, each indicating if standard
deviation (as a measure of ECMP imbalance) for
traffic averages for each external router-facing
interface on a given system has been outside
acceptable range for more than specified period of
time. Each set member has system_id key to identify
system whose ECMP imbalance the value
represents.
|
|
| systems imbalanced count (Match Count) |
Purpose: Count how many systems have external ecmp imbalance
anomaly true at any instant in time.
Input Stage: sustained_ecmp_imbalance
| Output Stage: system_tx_imbalance_count |
Number of systems with external ecmp imbalance.
|
|
| live system imbalanced (Range) |
Purpose: Evaluate if the number of imbalanced systems is within
acceptable range, which in this instance means less than
'max_systems_imbalanced' value which is a facade parameter
Input Stage: system_tx_imbalance_count
| Output Stage: live_system_imbalance_count |
Boolean indicating if the number of imbalanced
systems is within accepted range, i.e. less than
'max_systems_imbalanced" which is a facade
parameter
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|
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For more information about this probe, from the blueprint, navigate to
Analytics > Probes, click Create
Probe, then select Instantiate Predefined Probe
from the drop-down list. Select the probe from the Predefined
Probe drop-down list to see details specific to the probe.
