GigaStream Imbalance Notification
In GigaVUE OS nodes, traffic is distributed across the ports in a GigaStream based on the following criteria:
- Type and volume of the incoming traffic
- Configurations defined in the Advanced Hash Settings page for the selected line card or chassis. Refer to the Advanced Hashing section in the Fabric Management guide for more details.
Consider a scenario in which ip4src and ip4dst are configured as advanced hash methods. Accordingly, traffic is distributed based on the matching IP source and IP destination addresses.
- In case of high traffic volume on a particular IP address or subnet, one or more ports within the GigaStream group will receive more traffic compared to the other ports.
- Alternatively, if there is a low traffic volume on a particular IP address or subnet, one or more ports within the GigaStream group will receive lower traffic compared to the other ports.
A small variation in traffic volumes across the ports in a GigaStream is expected and is acceptable. Large variation in traffic volume causes packet drops due to over subscription or under subscription of ports. With the GigaStream imbalance notification functionality, the port statistics of the member ports in a GigaStream are validated to determine if the variation in traffic distribution across the ports does not exceed or fall below a user-defined threshold value limit. If traffic distribution is not within the allowed variance limit, the GigaVUE HC series and TA series devices generate SNMP traps that are sent to GigaVUE-FM based on which GigaStream imbalance alarms are triggered.
SNMP traps are generated in the devices based on the following criteria:
- Variance threshold % configured either through GigaVUE-FM or CLI (refer to the Example for more details)
- Distribution of traffic between the ports (on a 30 second interval)
- Change the Advanced Hash settings
- Use a Weighted GigaStream to apply more hashing buckets to under utilized ports and lesser hashing buckets to over utilized ports
The following SNMP traps are triggered in the devices:
- For imbalanced traffic distribution: gigamonSnmpGigastreamImbalanceNotification
- On recovery of balanced traffic: gigamonSnmpGigastreamRecoveryNotification
To manage the SNMP traps, you can either use the SNMP throttling feature or the GigaStream Imbalance notification feature. With SNMP throttling, it is possible for some of the recovery traps to get throttled resulting in inappropriate health status of the ports in the GigaVUE-FM GUI. Use the GigaStream Imbalance Notification feature to generate traps and trigger appropriate alarms.
Note: GigaStream Unhealthy alarm is raised to signify the imbalance in traffic distribution ( alarm description includes all the affected ports).
GigaStream Imbalance Threshold Priority Levels
Threshold values for GigaStream imbalance can be configured at the following levels:
Configuration Level | Description | Notes |
---|---|---|
Per GigaStream Level Configuration | Applies to a specific GigaStream in a device. | Has the highest priority and overrides the type level and global level configuration. |
Type Level Configuration | Applies to all GigaStreams of a particular type. | Has the second highest priority and overrides the global level configuration . |
Global Level Configuration
|
Applies to all GigaStreams. |
Has the lowest priority. |
The following table shows the various configurations that can be performed from the GUI:
Configuration Level | Details | Refer to |
---|---|---|
Per GigaStream Level Configuration |
Allows you to configure GigaStream Imbalance notification for a specific GigaStream in a device.
|
Configure GigaStream Imbalance per GigaStream |
Device Level Configuration |
Allows you to configure GigaStream Imbalance notification for all the GigaStreams in a device. |
|
GigaVUE-FM Level Configuration | Allows you to configure GigaStream Imbalance notification for all the GigaStreams in all devices managed by GigaVUE-FM. | Configure GigaStream Imbalance Threshold in GigaVUE-FM |
Note: For configuration using CLI, refer to the GigaVUE-OS CLI Reference Guide.
You can configure threshold values for GigaStream imbalance for the following GigaStream types:
- All GigaStreams
- Tool GigaStream
- Circuit GigaStream
- Hybrid GigaStream
- Stack GigaStream
Note: GigaStream Imbalance threshold notification functionality is applicable only for regular GigaStreams. Controlled GigaStreams and weighed GigaStreams are not within the scope of this functionality as traffic distribution is uneven within the ports.
Consider a GigaStream GS1 consisting of three member ports P1, P2, P3. Let the threshold variance be configured as 10%. Refer to the following table for details on how the threshold limits are calculated, based on which traps are triggered.
Time |
Port Utilization of Member Ports |
Average Port Utilization | Allowed variance based on configured threshold value | Upper and lower limits | Is SNMP Trap Triggered? |
---|---|---|---|---|---|
T1 |
|
60 | 6 |
Upper limit: 60+6 = 66 Lower limit: 60-6 = 54 The port utilization in all the ports in the GigaStream is within the threshold limit. |
No |
T2 (T1+30 seconds) |
|
20 | 2 |
Upper limit: 20+2 = 22 Lower limit: 0-2 = 18 The port utilization in port P2 is within the threshold limit, whereas port utilization in ports P1 and P3 is not within the threshold limit.
|
GigaStream Imbalance trap is triggered in the device and sent to GigaVUE-FM and the corresponding GigaStream Imbalance Threshold alarm is triggered. |
T3 (T1+60) |
|
20 | 2 |
Upper limit is 20+2 = 22 Lower limit is 20-2 = 18 The port utilization in all the ports in the GigaStream is within the threshold limit.
|
Trap is cleared. |
- If you configure the threshold value to '0', higher level threshold is applied to the Gigastream. For example, if you configure the threshold of a particular Gigastream to '0', it inherits its type-level threshold configuration. If type-level threshold is also configured as '0' then global-level threshold is applied to the Gigastream.
- If you configure the threshold value to -1, the feature is disabled on the given Gigastream. The GigaStream will no longer inherit its type-level/global-level threshold values and trap will also not be generated on account of variation in traffic distribution.
- You can configure email notifications for GigaStream Imbalance event occurrence. Refer to the Event Notifications section for details.
- Supported polling interval is 30s only.