Example for Configuring a Basic MLAG

Owned by Tracy Yang
Nov 13, 2023
9 min read

Networking Requirements

Figure 1 Basic MLAG Topology

In Figure 1, SwitchB dual accesses the network through SwitchA1 and SwitchA2 using LACP LAG.

At first, SwitchB accesses the network through SwitchA1. If SwitchA1 or the link between SwitchB and SwitchA1 fails, SwitchB cannot communicate with the network. To avoid service interruptions, we can configure MLAG on SwitchA1 and SwitchA2. When communication between SwitchB and SwitchA1 fails, traffic from the SwitchB will be switched to SwitchA2 seamlessly. When SwitchA1 or the link between SwitchB and SwitchA1 recovers, traffic from the SwitchB will be switched back to SwitchA1.

The peer link between SwitchA1 and SwitchA2 is configured to carry MLAG related control traffic and is very critical to the operation of MLAG function.

Procedure

SwitchA1

Step1         Configure the VLANs.                   

   admin@SwitchA1# set vlans vlan-id 15

                  admin@SwitchA1# set vlans vlan-id 16

                  admin@SwitchA1# set vlans vlan-id 4088 l3-interface vlan4088

                  admin@SwitchA1# set interface aggregate-ethernet ae1 family ethernet-switching port-mode trunk

                  admin@SwitchA1# set interface aggregate-ethernet ae1 family ethernet-switching vlan members 15

                  admin@SwitchA1# set interface aggregate-ethernet ae1 family ethernet-switching vlan members 16

                  admin@SwitchA1# set interface aggregate-ethernet ae2 family ethernet-switching native-vlan-id 4088

                  admin@SwitchA1# set interface aggregate-ethernet ae2 family ethernet-switching port-mode trunk

                  admin@SwitchA1# set interface aggregate-ethernet ae2 family ethernet-switching vlan members 15

                  admin@SwitchA1# set interface aggregate-ethernet ae2 family ethernet-switching vlan members 16

Step2         Configure MLAG interfaces with LACP mode.

                   admin@SwitchA1# set interface aggregate-ethernet ae1 aggregated-ether-options lacp enable true

Step3         Add member interfaces to a LAG.               

   admin@SwitchA1# set interface gigabit-ethernet ge-1/1/1 ether-options 802.3ad ae1

                  admin@SwitchA1# set interface gigabit-ethernet te-1/1/49 ether-options 802.3ad ae2

                  admin@SwitchA1# set interface gigabit-ethernet te-1/1/50 ether-options 802.3ad ae2

Step4         Configure an MLAG domain ID.

    admin@SwitchA1# set protocols mlag domain 10

    NOTE: Currently, only one MLAG domain is allowed to be configured on one MLAG device.

Step5         Specify SwitchA1 as MLAG Node 0.

    admin@SwitchA1# set protocols mlag domain 10 node 0

Step6         Configure the peer IP address and peer link port.

    admin@SwitchA1# set protocols mlag domain 10 peer-ip 10.10.0.2 peer-link ae2

    NOTE: Peer-link port should be configured as a LAG port.

Step7         Configure the L3 interface IP address for peer link port on local MLAG peer device.

                  admin@SwitchA1# set l3-interface vlan-interface vlan4088 address 10.10.0.1 prefix-length 24

Step8         Configure link ID for the MLAG member port.

                  admin@SwitchA1# set protocols mlag domain 10 interface ae1 link 2

   NOTE: The paired MLAG member ports must be bound to the same MLAG link ID.

Step9         Configure MLAG peer VLAN.

   admin@SwitchA1# set protocols mlag domain 10 peer-ip 10.10.0.2 peer-vlan 4088

Step10       Commit the configuration.

   admin@SwitchA1# commit

SwitchA2

The configuration on SwitchA2 is the same as SwitchA1.

Step1         Configure the VLANs.                   

   admin@SwitchA2# set vlans vlan-id 15

                  admin@SwitchA2# set vlans vlan-id 16

                  admin@SwitchA2# set vlans vlan-id 4088 l3-interface vlan4088

                  admin@SwitchA2# set interface aggregate-ethernet ae1 family ethernet-switching port-mode trunk

                  admin@SwitchA2# set interface aggregate-ethernet ae1 family ethernet-switching vlan members 15

                  admin@SwitchA2# set interface aggregate-ethernet ae1 family ethernet-switching vlan members 16

                  admin@SwitchA2# set interface aggregate-ethernet ae2 family ethernet-switching native-vlan-id 4088

                  admin@SwitchA2# set interface aggregate-ethernet ae2 family ethernet-switching port-mode trunk

                  admin@SwitchA2# set interface aggregate-ethernet ae2 family ethernet-switching vlan members 15

                  admin@SwitchA2# set interface aggregate-ethernet ae2 family ethernet-switching vlan members 16

Step2         Configure MLAG interfaces with LACP mode.

                   admin@SwitchA2# set interface aggregate-ethernet ae1 aggregated-ether-options lacp enable true

Step3         Add member interfaces to a LAG.               

   admin@SwitchA2# set interface gigabit-ethernet ge-1/1/1 ether-options 802.3ad ae1

                  admin@SwitchA2# set interface gigabit-ethernet te-1/1/49 ether-options 802.3ad ae2

                  admin@SwitchA2# set interface gigabit-ethernet te-1/1/50 ether-options 802.3ad ae2

Step4         Configure an MLAG domain ID.

    admin@SwitchA2# set protocols mlag domain 10

    NOTE: Currently, only one MLAG domain is allowed to be configured on one MLAG device.

Step5         Specify SwitchA2 as MLAG Node 1.

    admin@SwitchA2# set protocols mlag domain 10 node 1

Step6         Configure the peer IP address and peer link port.

    admin@SwitchA2# set protocols mlag domain 10 peer-ip 10.10.0.1 peer-link ae2

    NOTE: Peer-link port should be configured as a LAG port.

Step7         Configure the L3 interface IP address for peer link port on local MLAG peer device.

                  admin@SwitchA2# set l3-interface vlan-interface vlan4088 address 10.10.0.2 prefix-length 24

Step8         Configure link ID for the MLAG member port.

                  admin@SwitchA2# set protocols mlag domain 10 interface ae1 link 2

   NOTE: The paired MLAG member ports must be bound to the same MLAG link ID.

Step9         Configure MLAG peer VLAN.

   admin@SwitchA2# set protocols mlag domain 10 peer-ip 10.10.0.1 peer-vlan 4088

Step10       Commit the configuration.

   admin@SwitchA2# commit

SwitchB

Step1         Enable aggregation interface with LACP mode.

                   admin@SwitchB# set interface aggregate-ethernet ae1 aggregated-ether-options lacp enable true

Step2         Add member interfaces to a LAG.

                   admin@SwitchB# set interface gigabit-ethernet ge-1/1/1 ether-options 802.3ad ae1

                   admin@SwitchB# set interface gigabit-ethernet ge-1/1/2 ether-options 802.3ad ae1

Step3         Configure VLAN.

                   admin@SwitchB# set vlans vlan-id 15

                   admin@SwitchB# set vlans vlan-id 16

                   admin@SwitchB# set interface aggregate-ethernet ae1 family ethernet-switching port-mode trunk

                   admin@SwitchB# set interface aggregate-ethernet ae1 family ethernet-switching vlan members 15

                   admin@SwitchB# set interface aggregate-ethernet ae1 family ethernet-switching vlan members 16

Step4         Commit the configuration.

   admin@SwitchB# commit

Verify the Configuration

  • You can use the run show mlag domain command to display the global MLAG domain information.        
admin@SwitchA1# run show mlag domain summary
Domain ID: 10    Domain MAC: 48:6E:73:FF:00:0a    Node ID: 0
-----------------------------------------------------------------------
Peer Link  Peer IP          Peer Vlan  Neighbor Status  Config Matched   MAC Synced   # of Links
---------  ---------------  ---------  ---------------   --------------   ----------    ----------
ae2        10.10.10.2       4088       ESTABLISHED       Yes              Yes            1   
  • You can use the run show mlag link command to display MLAG link information.
admin@SwitchA1# run show mlag link summary
# of Links: 1
Link   Local LAG   Link Status   Local Status   Peer Status    Config Matched   Flood
----   ---------   -----------   ------------   -----------     --------------   -----
2      ae1          IDLE            UP            UNKNOWN        No              No
  • You can use the run show mlag consistency-parameter command to display the result of MLAG configuration consistency check, including the global and per MLAG configuration.
admin@SwitchA1# run show mlag consistency-parameter link 2
Port Configurations:
----------------------------------------------------------------
Property                 Local Value      Peer Value       Result
-----------------------  ---------------  ---------------  ------
MTU                      1514             1514             PASS 
Mac Learning             Yes              Yes              PASS 
Lag Mode                 LACP             LACP             PASS 
Native Vlan              1                1                PASS 
Port Vlan Mode           Trunk            Trunk            PASS 
Trunk Vlan Count         2                2                PASS  
Trunk VLAN IDs                                             PASS  

Spanning-Tree Configurations:
-----------------------------------------------------------------
Property                 Local Value      Peer Value       Result
-----------------------  ---------------  ---------------  ------
Mode                                                       PASS 

VXLAN Configurations:
-----------------------------------------------------------------
Property                 Local Value      Peer Value       Result
-----------------------  ---------------  ---------------  ------
Link   1 VXLAN           N/A              N/A              FAIL

admin@SwitchA1# run show mlag consistency-parameter summary
Overall : PASS
--------------
Global  : PASS
Link 2  : PASS

MLAG Configurations:
-----------------------------------------------------------------
Property                 Local Value      Peer Value       Result
-----------------------  ---------------  ---------------  ------
Domain ID                1                1                PASS 
Node ID                  0                1                PASS 
Peer VLAN                4088             4088             PASS 
Link Count               1                1                PASS 
Link IDs                 2                2                PASS 
                         
Spanning-Tree Configurations:
-----------------------------------------------------------------
Property                 Local Value      Peer Value       Result
-----------------------  ---------------  ---------------  ------
Enable                   No               No               PASS   

DHCP Snooping Configurations:
-----------------------------------------------------------------
Property                 Local Value      Peer Value       Result
-----------------------  ---------------  ---------------  ------
VLAN Count               0                4                FAIL  
VLAN IDs                                                   FAIL  

IGMP Snooping Configurations:
-----------------------------------------------------------------
Property                 Local Value      Peer Value       Result
-----------------------  ---------------  ---------------  ------
Enable                   No               No               PASS

VXLAN Configurations:
-----------------------------------------------------------------
Property                 Local Value      Peer Value       Result
-----------------------  ---------------  ---------------  ------
VXLAN                    N/A              N/A              PASS
VXLAN VNI Count          0                0                PASS 
VXLAN VNIs                                                 PASS
  •  You can use the run show lacp neighbor command to view the config information of LACP neighbor.
admin@SwitchA1# run show lacp neighbor
     Aggregated interface: ae1
     Port Number   Partner System ID               Partner Port Num   Port Priority   Admin Key   Oper Key   State
     -----------          -----------------------   ----------------   -------------    ---------  --------   -----
      ge-1/1/1         32768,08:9E:01:61:64:13       1                 32768            0x00       0x35        0x3D
      Aggregated interface: ae2
      Port Number   Partner System ID                    Partner Port Num   Port Priority   Admin Key   Oper Key   State
      ------------------------------------------------------------------------------------------------------------------
       te-1/1/49           32768,70:72:CF:B7:60:A5 73       73                  32768           0x00       0x50    0x3D 
       te-1/1/50           32768,70:72:CF:B7:60:A5 73       74                  32768           0x00       0x50    0x3D 


  


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