4.10 Getting Help in the CLI

The JUNOS CLI is very user -friendly when it comes to help. There are features that you might be familiar with, such as the question mark. The question mark can be used to tell you the possible next choices for typing commands on the command line. Some of the other features that might be new to you are help topic , help reference and help apropos . These features support a very robust help facility that is available through the CLI. It is like having a command reference and configuration guide built into the router. As you will see, these help features can be very useful for aiding in the configuration of your Juniper Networks router.

The help topic command displays the usage guidelines for a command, and the help reference command displays summary information about commands. The help apropos command offers syntax information about commands that contain a string you type on the command line. This feature is available in configuration mode only and is described in the configuration-mode section.

 lab@Chicago> help ?  Possible completions:   reference            Reference material   topic                Help for high level topics 

The next example shows the output from the help topic msdp group command. It tells how to use the commands to configure Multicast Source Discovery Protocol (MSDP).

 lab@Chicago> help topic msdp group  Configure MSDP Groups An MSDP router must know which routers are its peers (neighbors). You define the peer relationships explicitly by configuring the neighboring routers that are the MSDP peers of the local router. After peer relationships are established, the MSDP peers exchange messages to advertise active multicast sources. You can arrange peers into different groups. Each group must contain at least one peer. Arranging peers into groups is useful if you want to block sources from some peers and accept them from others or set tracing options on one group and not the others. To configure MSDP groups, include one or more of the following statements at the [edit protocols msdp group group-name] hierarchy level:    [edit protocols msdp]        group group-name {            disable;            export [ policy-name ];            import [ policy-name ];            local-address address;            mode <(mesh-group  standard)>;            traceoptions {                file name <replace> <size size> <files number> <no-stamp>                    <(world-readable  no-world-readable)>;                traceflag flag <flag-modifier> <disable>;            }            peer address; {                disable;                export [ policy-name ];                import [ policy-name ];                local-address address;                traceoptions {                    file name <replace> <size size> <files number>        <no-stamp>                        <(world-readable  no-world-readable)>;                    flag flag <flag-modifier> <disable>;            }        } The individual statements are discussed in separate sections. 

The help reference command gives a little more detail and provides a summary of the commands for MSDP.

 lab@Chicago> help reference msdp group  group       Syntax    group group-name {        disable;        export [ policy-name ];        import [ policy-name ];        local-address address;        mode (mesh-groupstandard)        traceoptions {            file name <replace> <size size> <files number> <no-stamp>                <(world-readable  no-world-readable)>;            flag flag <flag-modifier> <disable>;        peer address; {            disable;            export [ policy-name ];            import [ policy-name ];            local-address address;            traceoptions {                file name <replace> <size size> <files number> <no-stamp>                    <(world-readable  no-world-readable)>;                flag flag <flag-modifier> <disable>;            }        }    }       Hierarchy Level    [edit protocols msdp]       Description    Define an MSDP peer group. MSDP peers within groups share common traceoptions, if present and not overridden for an individual peer with the peer statement. To configure multiple MSDP groups, include multiple group statements.    By default, the group's options are identical to the global MSDP options. To override the global options, include group-specific options within the group statement.    The group must contain at least one peer.       Options    group-nameName of the MSDP group.    The remaining statements are explained separately in this chapter.       Usage Guidelines    See "Configure MSDP Groups".       Required Privilege Level    routingTo view this statement in the configuration.    routing-controlTo add this statement to the configuration.