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 [email protected]
  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
  ...