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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
  • All VOSS switches
  • All ERS switches
  • VSP 7024
  • VSP 8600
  • 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. enable
  2. configure terminal (all commands from here on out will be at the global or interface level when instructed)
  3. interface gigabitethernet [slot/port]
  4. encapsulation dot1q
  5. vlan create [vlan] type port-mstprstp 0
  6. vlan members remove 1 [slot/port]
  7. 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

  1. mlt [mlt_id]

Step 3: Configure LACP at interface level and remove STP on ports

  1. interface gigabitEthernet [ports]
  2. no spanning-tree mstp force-port-state enable
  3. lacp key [key]
  4. lacp aggregation enable
  5. lacp timeout-time short
  6. lacp mode active
  7. lacp enable
  8. exit

Step 4: Bind LACP key to MLT interface and enable LACP

  1. interface mlt [mlt]
  2. lacp key [key]
  3. lacp enable
  4. exit

Step 5: Enable LACP globally

  1. 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

  1. 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.

  1. vlan create [vlan] name [name] type port
  2. vlan configcontrol flexible
  3. vlan members remove 1 [ports]
  4. vlan members add [vlan] [ports]
  5. vlan ports [ports] pvid [vlan]
  6. vlan ports [ports] tagging tagAll filter-untagged-frame enable (optional)

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

  1. lacp key [key] mlt-id [mlt number]

Step 4: LACP parameters need to be configured for each port and THEN enable LACP

  1. interface ethernet [ports]
  2. lacp key [key]
  3. lacp mode active
  4. lacp timeout-time short
  5. lacp aggregation enable
  6. exit


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

Global Defaults:

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

Interface Level Defaults:

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

Verify the defaults:

  1. show run module mlt
  2. 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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