gNMI support for Routing Engine statistics for JTI

Junos telemetry interface (JTI) supports export of Routing Engine sensors using gRPC Management Interface (gNMI). gNMI is a protocol for configuration and retrieval of state information. Both streaming and ON_CHANGE export is supported using gNMI.
Export the following statistics using gNMI:

• Network discovery, ARP table state (resource path /arp-information/)
• Network discovery, NDP table state (resource paths /nd6-information/ and /ipv6-ra/)

To provision the sensor to export data through gNMI, use the Subscribe RPC defined in the gnmi.proto to specify request parameters. Streaming telemetry data through gNMI also requires the OpenConfig for Junos OS module. OpenConfig and Network Agent packages are bundled into the Junos OS image by default. Both packages support the JTI.