Finding the correct YANG model

Configure MDT using the solution from the first lab, if it is not already configured.

#XR1
telemetry model-driven
 destination-group TIG
  address-family ipv4 10.100.100.1 port 57500
   encoding self-describing-gpb
   protocol grpc no-tls
  !
 !
 sensor-group SENSOR1
  sensor-path Cisco-IOS-XR-infra-statsd-oper:infra-statistics/interfaces/interface/latest/generic-counters
 !
 subscription SUB1
  sensor-group-id SENSOR1 sample-interval 5000
  destination-id TIG

Add an additional sensor-path which exports the number of routes in the RIB from ISIS 1.

Answer

telemetry model-driven
 sensor-group SENSOR1
  sensor-path Cisco-IOS-XR-ip-rib-ipv4-oper:rib/vrfs/vrf[vrf-name="default"]/afs/af[af-name="IPv4"]/safs/saf[saf-name="Unicast"]/ip-rib-route-table-names/ip-rib-route-table-name[route-table-name="default"]/protocol/isis/as[as='1']/information

Explanation

This is quite tricky. First, I found a YANG model for the IPv4 RIB using the following tool:

yang-describe operational show route

This gave me:

Cisco-IOS-XR-ip-rib-ipv4-oper:rib/vrfs/vrf/afs/af/safs/saf/ip-rib-route-table-names/ip-rib-route-table-name/routes/route

From here, I found the following tutorial on xrdocs, which I based the path on: https://xrdocs.io/telemetry/tutorials/2016-12-23-streaming-bgp-route-and-neighbor-counts-with-mdt/

I found that I needed to specify the vrf, af-name, saf-name, route-table-name, and ISIS AS.

We can actually get the first four keys from the path that was given from the first yang-describe command.

From here, knowing that there is a /protocol/ path might be difficult. I would not have found that unless I found the xrdocs page.

Use the following Grafana query:

from(bucket: "telemetry")
  |> range(start: v.timeRangeStart, stop:v.timeRangeStop)
  |> filter(fn: (r) =>
    r._measurement == "Cisco-IOS-XR-ip-rib-ipv4-oper:rib/vrfs/vrf/afs/af/safs/saf/ip-rib-route-table-names/ip-rib-route-table-name/protocol/isis/as/information" and
    r._field == "active_routes_count"
  )

I shutdown XR2’s loopback1 and brought it back up to test that the data stream works. The counter goes from 3, to 2, and back to 3.