Configure Streaming Telemetry Sensor-Path on Cisco Devices

All streaming telemetry configuration has the following three component:

1. Sensor group - the data model that needs to be streamed out
2. Destination group - where the data is streaming to (collection system), how the data is streamed (encoding and transport)
3. Subscription - how often does the device push the data out - regularly based on configured interval, or on change

1. IOS-XR Configuration and Validation

Note: The example shows here has two destination for redundancy purpose to avoid data loss. At the collection end, the data needs to be deduped. The sample-interval is in ms unit.

Check the status of destination, sensor-path to ensure destination is active, and sensor-paths are resolved.

2. IOS-XE

3. NX-OS

Note: Although the encoding used in the example config here is GPB, it is actually refer to GPBKV or self-describe GPB as in IOS-XR. Users need to make sure to select matching encoding on the collector side. 

Cisco has a list of tools to help identify and explore ios-xr sensor paths.

1. Github

Go here: Github and browse models for specific release. Note: Telemetry only cares about operational *-oper.yang models, not *–cfg.yang, not *–act.yang.

2. PYANG

Download the interested yang model to a linux server. Use pyang to see the content of the model, kind of similar to snmpwalk. Compare names in the command you want to capture and the output of the YANG model

Following is an example to view the tree structure of interface stats yang model.

pyang -f tree Cisco-IOS-XR-infra-statsd-oper.yang --tree-path infra-statistics/interfaces/interface/latest/generic-counters
 
module: Cisco-IOS-XR-infra-statsd-oper
 +--ro infra-statistics
    +--ro interfaces
       +--ro interface* [interface-name]
          +--ro latest
             +--ro generic-counters
                +--ro packets-received?                    uint64
                +--ro bytes-received?                      uint64
                +--ro packets-sent?                        uint64
                +--ro bytes-sent?                          uint64
                +--ro multicast-packets-received?          uint64
                +--ro broadcast-packets-received?          uint64
<output snipped for brevity>

3. Advanced NETCONF Explorer

This is a graphical explorer for YANG models supported by a NETCONF device or service orchestrator. Features include:

Retrieve all YANG models supported by a device. Parse the YANG models and outputting a tree with all the nodes which can expand / collapse.

Filter the model tree by module name and searching the names and descriptions of the YANG nodes in it.

Browsing and searching live (operational) data for selected YANG models.

Download Advanced NETCONF Explorer - ANX code. Note: This tool is meant to explore yang models on a lab device. DO NOT run this tool against a production devices!

4. Telemetry Data Mapper

Telemetry Data Mapper - TDM to map data identifiers from SNMP, gRPC, NETCONF, CLI, etc. to each other.

TDM provides an offline, immutable view into advertised data availability from data models, with search affordance to quickly identify data of interest and the capability to map between data to aid in keeping track of what is roughly equivalent to what.

You will be able to access TDM

5. CLI

This is a manual process and SHOULD NOT run on production devices. The first step is to understand which “show output” you want to stream using Model Driven Telemetry. Let’s say we want to find the right path for RSVP interface output:

RP/0/RP0/CPU0:NCS5501_bottom#sh rsvp interface bundle-ether 26   
Thu Dec  7 18:27:56.646 PST

*: RDM: Default I/F B/W % : 80% [cfgd] (max resv/bc0), 0% [default] (bc1)

Interface                 MaxBW (bps)  MaxFlow (bps) Allocated (bps)      MaxSub (bps) 
------------------------- ------------ ------------- -------------------- -------------
Bundle-Ether26                   240G           240G           20M (  0%)            0 

After the “show output” was defined you need to find the corresponding XML schema inside the router, using “schema-describe” command:

RP/0/RP0/CPU0:NCS5501_bottom#schema-describe sh rsvp interface bundle-ether 26
Thu Dec  7 18:28:25.325 PST
Action: get
Path:   RootOper.RSVP.InterfaceBrief({'InterfaceName': 'Bundle-Ether26'})

After you found the corresponding XML schema, go and check the content of it. To do this you need to run “m2mcon” and use “get”:

At this step you have your show output, the schema you need and the fields of this schema. You need to find corresponding YANG model. Do this search based on the name (usually, it is clear which model you need), for RSVP you have just a single model: “Cisco-IOS-XR-ip-rsvp-oper.yang”

Use pyang tool to go through the model, try to find the path (section) that contains the same fields. In our case it will be:

We can also use the following command to retrieve live data on a device under test for validation:

run mdt_exec -s <sensor-path> -c <candence> 

All the counters on the screen are in JSON format. To see in a more human-readable format, use any preferred JSON formatter, e.g:

Following link has some very good write up about streaming telemetry. Happy Reading!

https://xrdocs.io/telemetry/