Command Line Interface

The Cisco Nexus 3550-H Hydra (formerly ExaLINK Hydra) can be configured via a command line interface. This interface can be accessed via SSH, telnet, or an industry standard serial interface.

Configuration mode

The command line interface can be used to both inspect the current configurations of the Nexus 3550-H, and modify the configuration. The command line can be used in either a modal or non-modal way. For example, commands that change the current configuration are prefixed with config. When executing multiple configuration commands, it is convenient to enter config mode. For example, to disable an interface, one can enter:

admin@EXALINK-HYDRA# configure interface ethernet1/1 shutdown
Interface "ethernet1/1" disabled

Alternatively, you can enter config mode and then disable the interface:

admin@EXALINK-HYDRA# config
admin@EXALINK-HYDRA(config)# interface ethernet1/1 shutdown
Interface "ethernet1/1" disabled

Note: in the above example that the command line prompt indicates that config mode is in use. To exit a mode, simply type exit:

admin@EXALINK-HYDRA(config)# exit

Additionally, there is a shortcut available for exit. Pressing Control+d is a shortcut for exit in any mode.

Note: that the interface has dropped back to the default mode. Importantly, typing exit within the default mode will log you out of the device.

Modal states can be nested, and typing exit will drop out of that level and up to the previous level. Typing end will drop out of all levels and return you to the top modal level. For example:

admin@EXALINK-HYDRA# config
admin@EXALINK-HYDRA(config)# interface ethernet1/1
admin@EXALINK-HYDRA(config-if-et1/1)# end

Creating and removing objects

The Nexus 3550-H is configured by creating or removing objects. An object represents a specific configuration and may have one or more ports as members, as well as a number of properties. There is no limit to the number of objects that can be created on the Nexus 3550-H apart from that imposed by the number of ports on the device.

All objects are created or removed using the same convention. Creation of an object is achieved by entering the desired object type followed by any required properties. For example, to create a tap:

admin@EXALINK-HYDRA# config tap ethernet1/1 ethernet1/4
Added input tap on interface "ethernet1/1", send to interface "ethernet1/4"

Removal of an object from the configuration is the same as creating the object, however the command is prefixed with no. To remove the tap created above, one would enter:

admin@EXALINK-HYDRA# configure no tap ethernet1/1 ethernet1/4
Removed input tap on interface "ethernet1/1", send to interface "ethernet1/4"

Help and autocompletion

The command line interface includes help and tab completion. Help can be requested at any point during use by pressing the ? character. If there are multiple parameter options that are valid from that point on, pressing ? will list them, for example:

admin@EXALINK-HYDRA# configure interface management1 ?
  interface  Configure interfaces
  exit       Exit management network configuration mode
  end        Exit configuration mode
  no         Negate a command or set to defaults
  ip         Configure IPv4 settings
  ipv6       Configure IPv6 settings

If there are no further parameter options valid, and ? is pressed, detailed usage information will be displayed, for example:

admin@EXALINK-HYDRA# configure interface management1 ip address ?
  <a.b.c.d/n>  IPv4 address and prefix length

Autocompletion and suggestions for any command can be obtained by pressing tab after having entered any partial command. For example, when creating a tap object, a list of available source or output ports can be obtained by pressing tab whilst the interface is expecting a port. In this example, the interface shows a list of available source ports after pressing tab:

admin@EXALINK-HYDRA# config tap
ethernet1/1   ethernet1/2   ethernet1/3   ethernet1/4   ethernet1/5
ethernet20/4  ethernet20/5  ethernet20/6  ethernet20/7  ethernet20/8

Command pipelines

The command line interface supports redirecting command output to standard Unix utilities such as grep and less, for example:

admin@EXALINK-HYDRA# show interface ethernet1/1 | grep Speed
 Speed is 10000 Mbps (1000/10000 Mbps supported)

Because this feature allows the user to run arbitrary shell commands, it is only available to users with admin privileges.

This page was last updated on Feb-18-2021.