Multi-Chassis Link Aggregation is the possibility with the Arista switch in order to utilize all interconnects in an active/active manner.
We will start from the below design :
with the the mlag configured between the 2 switch, all the path are in forward mode
CONFIGURATION PORT-CHANNEL
switch1#(config)#vlan 4094
switch1#(config)#name mlag
switch1#(config)#trunk group mlag
switch1#(config)#interface ethernet 47 - 48
switch1#(config-if-Et47-48)#description mlag
switch1#(config-if-Et47-48)#channel-group 100
switch1#(config-if-Po100)#switchport
switch1#(config-if-Po100)#switchport mode trunk
switch1#(config-if-Po100)#switchport trunk group mlag
switch2#(config)#vlan 4094
switch2#(config)#name mlag
switch2#(config)#trunk group mlag
switch2#(config)#interface ethernet 47 - 48
switch2#(config-if-Et47-48)#description mlag
switch2#(config-if-Et47-48)#channel-group 100
switch2#(config-if-Po100)#switchport
switch2#(config-if-Po100)#switchport mode trunk
switch2#(config-if-Po100)#switchport trunk group mlagNO SPANNING-TREE FOR MLAG VLAN
switch1#(config)#no spanning-tree vlan 4094
switch2#(config)#no spanning-tree vlan 4094CONFIGURATION INTERFACE PTP
switch1#(config)#interface vlan 4094
switch1#(config-if-Vl4094)#description mlag
switch1#(config)#ip address 100.100.100.0/31
switch2#(config)#interface vlan 4094
switch2#(config-if-Vl4094)#description mlag
switch2#(config)#ip address 100.100.100.1/31CONFIGURATION MLAG
switch1#(config)#mlag configuration
switch1#(config-mlag)#domain-id mlag1
switch1#(config-mlag)#local-interface Valn4094
switch1#(config-mlag)#peer-address 100.100.100.1
switch1#(config-mlag)#peer-link Port-Channel100
switch2#(config)#mlag configuration
switch2#(config-mlag)#domain-id mlag1
switch2#(config-mlag)#local-interface Valn4094
switch2#(config-mlag)#peer-address 100.100.100.1
switch2#(config-mlag)#peer-link Port-Channel100VERIFY
switch1#show mlag
....
MLAG Configuration:
domain-id : mlag1
local-interface : Vlan4094
peer-address : 100.100.100.1
peer-link : Port-Channel100
peer-config : consistent
MLAG Status:
state : Active
negotiation status : Connected
peer-link status : Up
local-int status : Up
system-id : xx:xx:xx:xx:xx:xx
dual-primary detection : Disabled
MLAG Ports:
Disabled : 0
Configured : 0
Inactive : 0
Active-partial : 0
Active-full : 0CONFIGURATION DUAL-HOMED LINK
switch1#(config)#interface ethernet 45
switch1#(config-if-Et45)#channel-group 45 mode active
switch1#(config-if-Po45)#switchport mode trunk
switch1#(config-if-Po45)#switchport trunk group server
switch1#(config-if-Po45)#mlag 45
switch2#(config)#interface ethernet 45
switch2#(config-if-Et45)#channel-group 45 mode active
switch2#(config-if-Po45)#switchport mode trunk
switch2#(config-if-Po45)#switchport trunk group server
switch2#(config-if-Po45)#mlag 45PECULIARITY
With the trunk group defined it is recommended to use the trunk group for all the vlans defined.
It is necessary to deploy on mlag port-channel all the vlans deployed
interface Port-Channel 100
description MLAG
switchport mode trunk
switchport trunk group mlag
switchport trunk group serverCHECK CONFIG
switch1#show interface Port-Channel 45
............................
Full-duplex, 20Gb/s
Active members in this channel: 2
... Ethernet45 , Full-duplex, 10Gb/s
... PeerEthernet45 , Full-duplex, 10Gb/s
..........................................
switch1#show mlag interface
mlag desc state local remote local/remote status
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45 Active-full Po45 Po45 up/up the 2 sides must be up, otherwise it’s needed to check configuration on both sides (switch and server)