Streaming Telemetry (or Model-Driven Telemetry) is a rapidly evolving technology for network monitoring. Metric data can be streamed from network devices continuously and at a high granularity thereby providing near real-time access to operational device metrics. NetIM can subscribe to specific data using standards-based YANG data models.

NetIM sets up a subscription to a data set in a YANG model. A subscription is a contract between a subscription service and a subscriber that specifies the type of data to be pushed. Subscription allows clients to subscribe to metric data and the device pushes the data to the collector for the subscribed data. Streaming telemetry data can be sent periodically or on-change.

NetIM currently expects periodic. Streaming telemetry configuration can also be dial-in or dial-out. Streaming telemetry provides device metric data to NetIM at a much higher frequency, more efficiently than classic SNMP is able to do. NetIM’s Streaming Telemetry support populates existing metric classes and is configured per device within the NetIM Device Manager.

Many resources exist for learning about streaming telemetry and vendor implementations. We do not attempt to duplicate the many excellent sources of material that exist for reference. We provide basic information on configuring your network devices for streaming telemetry. You should reference each vendor’s reference and configuration guides for comprehensive information on how to configure vendor devices for streaming telemetry. We will focus on how you configure NetIM to successfully receive the streaming telemetry data.

NetIM’s Model-driven Telemetry Receiver microservice is hosted on the NetIM Core VM. Use the IP address of the core VM as the address to use for configuring streaming telemetry on your network devices (at TCP port 57000 for dial-out). Check with the device vendor regarding which specific models and OS versions support streaming telemetry. In some cases, additional vendor feature licensing may be required for the devices to support streaming telemetry.

For streaming telemetry, configuration is required on NetIM UI, as well as, on the device. You must first ensure that you have an existing device object with interfaces in NetIM. The NetIM device model can be created by using either CLI data or SNMP data. However, you should ensure that SNMP polling is turned off for the devices for which you want the streaming telemetry data. Once the device model is created, configure the actual network device and then NetIM for telemetry collection.

NetIM supports both dial-in and dial-out.

For dial-in, NetIM creates a gNMI subscription template. The NetIM template requests that metric data to be provided at 10-second granularity. The device may abide by the 10-second granularity request or ignore it. The actual metric granularity provided is negotiated with the device with the requested granularity in the template just a suggestion to the device.

Communication between the device and NetIM is encrypted as TLS is enabled by default. TLS can be disabled to support unencrypted communication. Unencrypted communication requires manual configuration. SSL certificate validation can also be enabled.

We will document some details on how to configure various device types for Streaming Telemetry integration. This documentation is not a replacement for your device vendor configuration guide.

Cisco IOS-XR Dial-Out Support

IOS-XR Sample Dial-Out Configlet

Cisco IOS-XR Dial-In Support

IOS-XR Sample Dial-In Configlet

Regardless of whether you are doing dial-in or dial-out on the Nexus, you must ensure the following features are enabled on your NX-OS device:

NX-OS Sample Dial-Out Configlet

Cisco NX-OS Dial-Out Support

NX-OS Dial-In Sample Configlet

Additional configuration is not required for NX-OS dial-in.

Cisco NX-OS Dial-In Support

Cisco IOS-XE Dial-Out Support

IOS-XE Example Dial-Out Configlet

Dial-in Sample Configlet

You can configure NetIM Streaming Telemetry to use TLS with either CA-signed or self-signed certificates.

When the Model-driven Telemetry microservice’s telegraf instance starts up, required keys and certificates are created in a directory on the NetIM Core VM:

/home/netimadmin/common/core-tenant-stack/1/telemetry-telegraf/cert

The files of interest are:

The telegraf instance configuration file points to both the telegraf.key and telegraf.pem file, by default. At the end of the signing process, both of those files need to be used/paired from the signing process and need to be named exactly as shown.

In order to use an external root CA, perform the following steps:

When the streaming telemetry collector service starts up, it will create (if they do not already exist) a new private key for telegraf and a self-signed certificate for devices to use for dial-out. The self-signed certificates will be generated in the form of telegraf.crt and telgraf.pem as well as the private key and signing request in telegraf.key and telegraf.csr, respectively. NetIM stores these files on the NetIM Core VM in the directory: /home/netimadmin/common/core-tenant-stack/1/telemetry-telegraf/cert

If you want to use NetIM-generated self-signed certificates for dial-out workflows, you need to copy the certificate (telegraf.pem) to the respective devices and configure accordingly.