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How To Configure LACP Over MLT

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TitleHow To Configure LACP Over MLT
How To Configure LACP over MLT
VSP 4000/7024/7200/8000
ERS 8000/3000/4000/5000/VSP7024
All supported software versions

Below are the steps to configure LACP over MLT on VSP 4000/7200/8000 and ERS 8000:
NOTE: It is advised to shutdown the ports prior to the configuration of MLT/SMLT/LACP  
NOTE: The LACP "key" is what binds the MLT instance to the LACP instance. You cannot assign ports to both MLT and LACP at the same time.

Step 1: Create VLAN, Tag the ports, Remove ports from VLAN 1, and Add ports to VLAN
1. Type enable
2. Type configure terminal (all commands from here on out will be at the global or interface level when instructed)
3. Type interface gigabitethernet [slot/port]
4. Type encapsulation dot1q
5. Type vlan create [vlan] type port-mstprstp 0
6. Type vlan members remove 1 [slot/port]
7. Type vlan members add [vlan] [slot/port]
(NOTE: When pre-configuring linked down / disabled ports, VLANs MUST be assigned to the physical ports as in Step#7 above.  This takes additional time since only one VLAN member can be added at a time)
(NOTE:  When configuring linked up / enabled ports, you can use "mlt <MLT_ID> vlan <VLAN_ID>" where you can create separate VLANs with a comma, such as "mlt 1 vlan 10,20,30".  However to use the multi-vlan configuration method, you must first create the MLT "mlt 1" and set encapsulation to dot1q "mlt 1 encapsulation dot1q", then followed by "mlt 1 vlan 10,20,30"

Step 2: Create MLT

  • Type mlt [mlt_id]

Step 3: Configure LACP at interface level and remove STP on ports
1. Type interface gigabitEthernet [ports]
2. Type no spanning-tree mstp force-port-state enable
3. Type lacp key [key]
4. Type lacp aggregation enable
5. Type lacp timeout-time short
6. Type lacp mode active
7. Type lacp enable
8. Type exit

Step 4: Bind LACP key to MLT interface and enable LACP
1. Type interface mlt [mlt]
2. Type lacp key [key]
3. Type lacp enable
4. Type exit

Step 5: Enable LACP globally

  • Type lacp enable

Note: Ports need to be in the same PVID, port speed, duplex, and VLAN before they can be added into LACP 

Step 1: First enable tagging on the ports

  • Type vlan ports [ports] tagging tagAll

Step 2: Create VLAN, Change mode to "flexible", remove from VLAN 1, add ports to VLAN, change PVID , and drop untagged frames on ports.
Type vlan create [vlan] name [name] type port
Type vlan configcontrol flexible
3. Type vlan members remove 1 [ports]

4. Type vlan members add [vlan] [ports]
5. Type vlan ports [ports] pvid [vlan]
6Type vlan ports [ports] tagging tagAll filter-untagged-frame enable (optional)

Step 3: Create LACP MLT binding (MLT is automatically created with this step)

  • Type lacp key [key] mlt-id [mlt number]

Step 4: LACP parameters need to be configured for each port and THEN enable LACP
Type interface ethernet [ports]
Type lacp key [key]
Type lacp mode active
Type lacp timeout-time short
Type lacp aggregation enable
6. Type exit

To default (undo) the configuration, see below commands:

Global Defaults:
1. Type no mlt [mlt]
2. Type show mlt (verify the members are gone)
3. Type default lacp key [key]
4. Type default lacp system-priority

Interface Level Defaults:
1. Type int ether [ports]
2. Type default lacp aggregation enable
3. Type default lacp key
4. Type default lacp mode
5. Type default lacp priority
6. Type default lacp timeout-time

Verify the defaults:
1. Type show run module mlt
2. Type show run module lacp


Additional notes
If you require additional assistance, please contact GTAC support:

- If non Avaya devices are connected, configure the static bundling on the ports where SMLT links are connected.
- If server is connected, make sure that both the ports of the server are configured as active - active.
- If system priority and port priority values are configured then make sure these are same on both the Cores.

LACP PDU uses these port priority to form the system ID [switch MAC(6 bytes)+ system priority(2 bytes)] value while sending LACP control messages to the partner, when different system and port priority values are configured on VSP-8ks the sys-id value changes when LACP PDU is sent which causes issues with link aggregation



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