5.2 SR OS Classic CLI Navigation and Operations

Recognize the CLI engine

The Nokia SR OS Classic CLI is a hierarchical command interface found in established deployments and documentation. The current NRS I course uses MD-CLI, so this lesson helps you recognize Classic syntax and interpret older examples. Do not paste Classic commands into an MD-CLI configuration context: object keys, administrative-state commands, and activation workflows differ.

A Classic prompt commonly includes a CPM letter, system name, and context path using greater-than signs. For example, A:R1>config>router# identifies a router configuration context. A leading asterisk indicates configuration changes not yet saved. This differs from the MD-CLI candidate-change indicator discussed next.

Navigate the hierarchy

Entering configure router from the root moves into the routing configuration hierarchy. Entering an interface context scopes subsequent commands to that interface. Context affects meaning: no shutdown under a port enables that port administratively, while the same words under another object affect that object.

Use context-sensitive help and completion to check available commands and parameters. A command copied without its parent context is incomplete evidence of how it works. Interface names containing spaces require quoting, and a physical port identifier is different from a named IP interface.

The exit command moves out of a context, and exit all returns to the root. Neither saves configuration. Check shortcuts in the matching release documentation rather than inferring behavior from another vendor's CLI.

Inspect before changing

A read-only sequence starts with the system and narrows to the affected service:

show version
show port
show router interface
show router route-table
show service service-using

These are command examples, not captured output from a running lab. Check release-specific syntax when adding filters, service IDs, or instance arguments. show router interface and show port answer different questions. A port can be physically Up while an IP interface is disabled or addressed incorrectly. A route can exist in Base while the customer's service uses a different routing instance.

Within a configuration context, info displays local configuration. info detail includes defaults where supported. When reading a listing, first identify the parent context and then the object being configured. An address alone does not tell you whether it belongs to Base, IES, or a private VPRN.

Immediate activation and persistence

Classic configuration normally changes the running system as commands are entered. An entire multi-line example is not automatically staged simply because it is indented. Intermediate changes can interrupt traffic before the final line is entered.

For example, changing a port's encapsulation can affect existing SAPs. Changing an interface address can remove connected reachability and disrupt routing sessions. A correct final configuration does not make every intermediate step harmless. In a lab, observe state before and after a small change so its effect is clear.

The active configuration also needs to survive restart. The Boot Options File (BOF) identifies the configuration location used during startup. admin save saves the current running configuration to the configured startup location in its ordinary form. An explicitly specified alternate destination is a backup file; it does not prove startup will load that backup.

Saving and successful operation are separate checks. Saving a wrong route preserves the wrong route. Saving does not create a missing physical link or supply an upstream return route.

Read an interface example

This illustrative Classic fragment defines a named Base-router interface. The supporting network port must already be provisioned and enabled.

configure router
    interface "to-R2" create
        address 192.0.2.1/30
        port 1/1/1
        no shutdown
    exit
exit all

The address and prefix define the local Layer 3 endpoint and subnet. The port binds the logical interface to connectivity. no shutdown enables the interface administratively. The peer might use 192.0.2.2/30, but that peer must actually be configured; this fragment does not configure both ends.

Afterward, inspect interface state, the connected route, and neighbor resolution. An interface showing Up does not demonstrate application success. If the peer is unreachable, check the subnet, physical port, encapsulation, filtering, and peer configuration. If the peer responds but a remote destination does not, check routes and the return path rather than assuming the local interface needs a new address.

Keep engines and states distinct

Classic uses forms such as no shutdown and commonly create for object creation. MD-CLI uses YANG-modeled objects, candidate edits, and commit. Configuration files are not interchangeable merely by changing punctuation.

When reviewing a scenario, distinguish navigating into a context, changing active configuration, and saving persistent configuration. Leaving a context changes navigation only. A Classic route can affect traffic before it is saved. If an unsaved change disappears after reboot, inspect both running configuration and the startup location before concluding the original command was ignored.

For practice, describe the result of each command before entering it: what object changes, when does it activate, how will you observe it, and how will it persist? This is more useful than memorizing a prompt string without understanding its context.

Primary reference

Nokia SR OS documentation, checked October 20, 2026. Use the matching Classic CLI reference for the lab release.