flokinet-001 - Introduction to the Arista CLI

(and a bit about how it works with containerlab and docker)

Tech Stack overview

• VM in the Hetzner Cloud (named “netlab.nanocat.net”)
• .. running Linux (Debian 11)
• .. and docker
• .. and containerlab
• containerlab creates containers based on a YAML file
• and runs EOS images (called cEOS) that I downloaded from Arista.com
• (and also tiny Linux images, to act as “PCs” in the LAB)
• (and also:)
  • Azure SONIC
  • Juniper cRPD
  • Cumulus VX
  • Keysight IXIA-C
  • Nokia SR-Linux

Connecting to the lab server

• Open your favourite Terminal Emulator
• SSH to the netlab server:

•   $ ssh-keygen -R netlab.nanocat.net   <- delete the cached fingerprint
                                            (lab server rebuilt frequently)
    $ ssh lab@netlab.nanocat.net
    Password: (generated fresh each week)

• List the running containerlab devices:

•   $ sudo containerlab inspect --all

• Connect to an Arista device:

•   $ sudo docker exec -it clab-device–name Cli

• .. or connect to a Linux device:

•   $ sudo docker exec -it clab-pcXX-name bash

enable and disable modes

• You will almost always enter enable as your first command after logging into your EOS (or IOS) device.

• enable (privileged) mode

  •   router>enable
      router#

  • prompt#
  • changes to the configuration possible
  • more access to detailed show commands

• disable (unprivileged) modes

  •   router#disable
      router>

  • prompt>
  • no configuration changes possible
  • safe, even for public access (search the web for “bgp looking glass telnet”)

? and <TAB>

• ? and <TAB> are used for help and command completion respectively. Try entering these commands:

•   router#show ?
    router#show ip ?
    router#show ip route ?
    router#sh<TAB> ip ro<TAB>

• Commands can be abbreviated to their shortest unambiguous length. Try these:

•   router#show running-config
    router#show running
    router#show run
    router#sh run
    router#sh ru

The “show” command

• Show commands tell us about the device hardware status, its protocols, software version, and so on. Try these commands:

•   show version
    show running-config
    show interface
    show interface status
    show ip interface
    show ip interface brief

Changing the Configuration

• Entering “Global Configuration Mode”:

•   router#configure
    router(config)#

• Configuring an interface:

•   router(config)#interface ethernet1
    router(config-if-eth1)#description This interface connects to the switch
    router(config-if-eth1)#

• Exiting interface configuration, back to global config, then exit config mode:

•   router(config-if-eth1)#exit
    router(config)#exit
    router#

• Look at the configuration:

•   router#show running-config

Configuring an interface

• Configuring an IP address on an ethernet interface:

•   router#configure
    router(config)#interface ethernet1
    router(config-if)#ip address 172.17.0.1/24
    ! IP configuration will be ignored while interface Ethernet1 is not a routed port.
    router(config-if)#no switchport
    router(config-if)#exit
    router(config)#exit
    router#show ip interface brief
    ...

Reconfiguring an interface

• Changing an IP address on an ethernet interface:

•   router#configure
    router(config)#interface ethernet1
    router(config-if-eth1)#ip address 10.0.0.1/24
    router(config-if-eth1)#end
    router#show ip interface brief
    ...

Reconfiguring an interface, again

• Removing the IP address from an ethernet interface:

•   router#configure
    router(config)#interface ethernet1
    router(config-if-eth1)#no ip address
    router(config-if-eth1)#end
    router#show ip int brief
    ...

Discovering our neighbours

• Checking our LLDP neighbours:

  router#show lldp neighbor
  ...

• Ping another device:

•   router#ping 10.0.0.4
    ...