DX NetOps Spectrum SNMPv3 Performance Improvements

Products

Network Observability Spectrum

Issue/Introduction

Cause

Changes to increase SNMPv3 performance

Resolution

For all releases between NetOps 22.2.5 and 25.4.1 the following parameters need to be set in the $SPECROOT/SS/.vnmrc file:

fix_v3_profile_lock=false
failed_cache_for_unmanaged_trap=true
tds_local_v3_profiles_store=true
v3_profile_hash_factor=16384

A SpectroSERVER restart is needed for the changes to take effect.

Once NetOps 25.4.2 is released the default values will be set in the code to:

fix_v3_profile_lock=true
failed_cache_for_unmanaged_trap=true
tds_local_v3_profiles_store=true
v3_profile_hash_factor=16384

These will be removed from the $SPECROOT/SS/.vnmrc by the installer but again are set in the code with the defaults noted so you do not need to add them back in unless directed by NetOps Support:

fix_v3_profile_lock=
failed_cache_for_unmanaged_trap=

Additional Information

These changes were introduced in NetOps 22.2.5

Additional information can be found here:

https://techdocs.broadcom.com/us/en/ca-enterprise-software/it-operations-management/spectrum/24-3/managing-network/modeling-and-managing-your-it-infrastructure/snmpv3-support.html

Added a new VNM model Attribute, FlushSnmpv3ProfilesInterval (0x13429)

- If the value of this attribute is non-zero, DX NetOps Spectrum starts the timer to flush the SNMP v3 remote profiles periodically. This non-zero value represents the interval in days.
- If the attribute value is set to 0, timer will be stopped. By default, the value is 0
- The above feature is targeted to flush the remote profile cache (reset snmpv3 authentication) for every device at a certain interval and let the cache rebuild for every v3 device based on its poll.

Added a new .vnmrc parameter that allows you to configure Hash Factor for remote profiles

v3_profile_hash_factor=

- All the remote SNMPv3 profiles are maintained in a hashTree(cache) and the value of 256 is the load factor used to build the hash key. This feature is useful for customers who are not using unique profiles / same profile across multiple devices. Setting a prime high value gives a more unique hash key for better performance.

Added a new .vnmrc parameter that optimizes the performance of the local SNMPv3 profiles search by storing them in a hash table instead of a list.

tds_local_v3_profiles_store=

As of 23.3.11 the following parameters were added:

fix_v3_profile_lock=

Spectrum introduces a new parameter that optimizes the performance of unmanaged trap processing by using a separate mutex to avoid thread latencies. By default, this functionality is disabled.
Note on Version Recommendations: For releases between 22.2.5 and 25.4.1, fix_v3_profile_lock should be set to false. In these earlier versions, the feature was disabled by default to prevent potential thread latencies. Starting with version 25.4.2, the feature has been optimized for stability and performance, and the code-level default is now true.

failed_cache_for_unmanaged_trap=

Spectrum optimizes the performance of unmanaged trap processing by introducing a failed cache mechanism. When Spectrum continues to receive unmanaged traps that do not match the SNMPv3 local profiles, you can choose to enable the
failed cache functionality. Spectrum then adds the IP address associated with these traps to the failed cache. Subsequently, whenever a trap comes from the same IP address, Spectrum checks the failed cache. If the IP address is present in the failed cache, Spectrum disregards the trap. This ability eventually reduces CPU utilization and enhances overall performance.

What is meant by “remote profiles”?

Definition: Remote profiles are internal cache entries maintained by the SpectroSERVER to decrypt SNMPv3 responses.
Creation: While 'Local Profiles' (created in OneClick) contain the user credentials, 'Remote Profiles' are built dynamically during polling by associating those credentials with the specific SNMPv3 EngineID returned by the device. This cache is automatically cleared and rebuilt upon every SpectroSERVER restart.

Upgrade Note: While the Spectrum installer is designed to remove these parameters from the .vnmrc file during upgrades to 25.4.2 and higher, it may occasionally fail to remove lines that were manually added or modified in previous versions. If these parameters persist after upgrading to 25.4.2+, they are obsolete and should be manually deleted from the .vnmrc followed by a SpectroSERVER restart.