How to configure Arista switches

Saving your changes

If you don't enter write at the end, everything is lost after reboot.


Entering conf mode


Setting password

username admin secret <passwordhere>

Setting name

hostname <NAME>

By default set it to switch-placeX. While the placeX part is indeed redundant, it is necessary to be able to distinguish switch1.place5 and switch1.place6.

Creating a VLAN

vlan <ID-OF-VLAN>

Putting a port into a untagged vlan

interface EthernetXX
   switchport access vlan YY

Creating a port channel (= LACP = bonding)

  • go to the interface that you want to be in the port-channel
  • configure it
interface EthernetXX
   channel-group XX mode active

Creating a port channel over multiple switches using MLAG

interface EthernetXX
   channel-group XX mode active
interface port-channel XX
   mlag XX

And if you want to have tagged/trunk port:

   switchport mode trunk 

If you want to have untagged connections to be automatically tagged:

switchport trunk native vlan <VLAN>

If you want to allow fallback of lacp:

port-channel lacp fallback static
port-channel lacp fallback timeout 20

Upgrading a switch

  • copy the image from usb to flash
  • change the boot config
  • don't forget to write
  • reload
copy usb1:/EOS-4.14.4.swi flash:/EOS-4.14.4.swi
configure terminal
boot system flash:/EOS-4.14.4.swi
show boot-config

Configuring MLAG

  • Create a port channel for communication
  • Configure the mlag over it
  • Assuming the switches are connected by ethernet 47 and ethernet 48
  • Assuming that the switches use vlan 13
  • ZZ = ip suffix of the switch
  • WW = ip suffix of the other switch
  • mlagdomain = something local
interface ethernet 47
    channel-group 47 mode active

interface ethernet 48
    channel-group 47 mode active

interface Port-Channel47
   switchport mode trunk
   switchport trunk group mlag-aristas

vlan 13
   name mlag-aristas
   trunk group mlag-aristas

interface Vlan13
   no autostate
   ip address 10.3.4.ZZ/24

mlag configuration
   peer-address 10.3.4.WW
   local-interface Vlan13
   peer-link Port-Channel47

Combining (MLAG+nolacp) + (Trunk+untagged vlan fallback)

  • Allow servers to netboot
  • Without LACP active
  • Without VLAN tagging active

Configuration valid for both switches:

interface Port-Channel1
   switchport trunk native vlan 10
   switchport mode trunk
   port-channel lacp fallback static
   port-channel lacp fallback timeout 20
   mlag 1
interface Ethernet1
   channel-group 1 mode active

Configuring BGP

  • XX = ip suffix
router bgp 209898
   router-id 0.0.0.XX
   bgp default ipv6-unicast
   maximum-paths 4
   bgp listen range 2a0a:e5c0:1:8::/64 peer-group ungleich remote-as 209898
   neighbor ungleich peer-group
   neighbor ungleich maximum-routes 12000 

Updated by Nico Schottelius about 1 year ago · 15 revisions