The most robust and common method to prevent an EEM applet from re-entering itself is to implement a re-entry guard using a global variable (e.g., with the ‘info’ namespace). When the applet triggers, it first checks if a flag (like ‘busy’) is set. If not, it sets the flag, performs the corrective action, and then clears the flag after a suitable delay or upon completion. This ensures the applet logic is not re-executed while it is already handling the previous event. Rate-limiting the event or adding a simple wait does not reliably prevent concurrent or overlapping executions from the same triggering condition.

When the external connection is up but no data flows, the issue is likely internal to the subscription configuration or data encoding. The ‘show telemetry internal subscription’ command provides detailed, low-level status for each subscription, including its state (Active, Suspended), the number of encoding errors, and the last error message. This is the most direct diagnostic tool to see if the device is attempting to encode and send data, and if not, why the subscription itself is failing internally, such as an unsupported sensor path or an encoding mismatch.

In the pyATS/Genie framework, the ‘learn()’ method is a powerful abstraction for data collection. It executes the necessary CLI commands (like ‘show version’, ‘show inventory’, etc.) behind the scenes, parses the unstructured text output, and returns a structured Python object (a ‘Learn’ object). This object’s ‘.info’ attribute contains a dictionary with the parsed data (e.g., version, serial number), making it easily consumable by automation scripts without manual text scraping. It does not configure, install, or execute arbitrary commands.

For ZTP to initiate automatically on boot, the global configuration command ‘zerotouch enable’ must be present in the startup-config. If this command is missing, the router will not attempt to run the ZTP process, even if it receives the correct DHCP options and downloads the script. The other options are less likely: Option 66 is not strictly required if the URL in option 67 is fully qualified; file permissions on a freshly downloaded script are typically handled by the ZTP process; and a clock issue would more likely prevent the HTTPS download itself, not the execution of an already-downloaded script.

For a gRPC dial-in (where the collector initiates the connection and subscription), the core elements of the subscription request are the ‘sensor-path’ (which identifies the specific YANG model nodes to subscribe to, e.g., ‘Cisco-IOS-XE-process-cpu-oper:cpu-usage/cpu-utilization’) and the ‘sample interval’ (which defines how often periodic updates should be sent, e.g., every 30 seconds). A subscription ID is often assigned by the router in its response, not strictly required from the client initially. SNMP and TFTP are unrelated to gRPC telemetry.

While `string match` could work, using `regexp` (regular expression) is the most precise and robust method for extracting specific patterns from unstructured CLI output. The regexp `{line protocol is (\w+)}` will search for that exact phrase and capture the following word (e.g., ‘up’, ‘down’, ‘administratively down’) into the variable `protocol`. The script can then conditionally check if `$protocol` equals “up”. This method is less fragile than relying on string position (`string first`) or fixed word indexes (`lindex`), as the output format might vary slightly across platforms or scenarios.

This is a fundamental distinction in NETCONF. The `` operation retrieves a snapshot of both configuration data (from datastores like running) and operational state data (e.g., interface statistics, routing table entries, learned MAC addresses). The `` operation, in contrast, retrieves data only from a specified configuration datastore (running, startup, candidate) and does not include operational state. This separation allows network management applications to distinguish between intended configuration and current device state.

To retrieve configuration or state data via RESTCONF, a GET request is used. The URI must point to the ‘data’ resource followed by the structured path of the YANG node. The header ‘Accept: application/yang-data+json’ (or xml) tells the server the desired encoding for the response. Option B describes an RPC/operation call, which is not needed for simple data retrieval. Option C incorrectly uses ‘/config’ instead of ‘/data’. Option D is a write operation (PUT) used for configuration, not retrieval.

The Guest Shell is a Linux container that runs within the IOS XE IOx (Application Hosting) framework. The fundamental prerequisite for using Guest Shell is enabling IOx globally with the command `iox` in global configuration mode. Without IOx enabled, the ‘guestshell’ command and associated infrastructure will not be present. While a specific OVA package may need to be installed, the absence of the command itself typically points to IOx not being enabled. Manufacturing mode is not required, and VLAN assignment is a configuration detail after the service is available.

The most robust and common method to prevent an EEM applet from re-entering itself is to implement a re-entry guard using a global variable (e.g., with the ‘info’ namespace). When the applet triggers, it first checks if a flag (like ‘busy’) is set. If not, it sets the flag, performs the corrective action, and then clears the flag after a suitable delay or upon completion. This ensures the applet logic is not re-executed while it is already handling the previous event. Rate-limiting the event or adding a simple wait does not reliably prevent concurrent or overlapping executions from the same triggering condition.0