Configuring LACP on a port

Configure LACP on a port to enable or disable LACP on the selected ports.

You must use the LACP keys to determine which ports are eligible for link aggregation. The LACP keys are defined by the ports after you configure the multilink trunk. You can aggregate the ports key that match the MLT key into that multilink trunk.

Note

Note

When enabling or disabling LACP on a port, as a best practice, disable the port first and re-enable the port after the configuration is complete.

The minimum LACP configuration is as follows:

  • Assign a given key to a set of ports.

  • Assign the same key to an MLT with no members. The ports will automatically become MLT members.

Keys do not have to match between two LACP peers.

About this task

Important

Important

Changes made at the global level override and reset all port level settings.

A port can operate in active or passive mode. You can configure a port to be an individual link or an aggregated link.

Note

Note

When using LACP with private VLANs, configure the private VLAN at the interface level.

Procedure

  1. Enter Interface Configuration mode:

    enable

    configure terminal

    interface GigabitEthernet {slot/port[/sub-port][-slot/port[/sub-port]][,...]} or interface vlan <1–4059>

    Note

    Note

    If the platform supports channelization and the port is channelized, you must also specify the sub-port in the format slot/port/sub-port.

  2. Assign an LACP key to a set of ports.

    lacp key <1-512|defVal>

  3. Change the LACP mode:

    lacp mode <active|passive>

  4. Change the port priority:

    lacp priority <0-65535>

  5. Optional: Change the system priority:

    lacp system-priority <0-65535>

  6. Configure aggregation for the port:

    lacp aggr-wait-time <200-2000>[aggregation enable]

    If you do not configure the optional parameter, the system uses the default values.

  7. Configure parameters for the partner device at the opposite end of the link:
    Note

    Note

    All the parameters beginning with partner are for debug purposes only. If you configure these commands locally and there is a mismatch with what's learned from the partner, there will be trace or log message.

    lacp partner-key <0-65535|defVal>

    lacp partner-port <0-65535>

    lacp partner-port-priority <0-65535>

    lacp partner-state <0-255 | 0x0-0xff>

    lacp partner-system-id 0x00:0x00:0x00:0x00:0x00:0x00

    lacp partner-system-priority <0-65535>

  8. Configure additional LACP parameters as required:

    lacp enable [fast-periodic-time <200-20000>] [slow-periodic-time <10000-30000>] [timeout-time <long|short>] [timeout-scale <2-10>]

    If you do not configure the optional parameters, the system uses the default values.

Example

Configure LACP on ports 1/2 and 1/3:

Switch:1(config)# interface gigabitethernet 1/2–1/3

Switch:1(config-if)# lacp key 1 timeout short

Switch:1(config-if)# lacp aggregation enable

Switch:1(config-if)# lacp enable

Variable definitions

Use the data in the following table to use the lacp command.

Note

Note

All the parameters beginning with partner are for debug purposes only. If you configure these commands locally and there is a mismatch with what's learned from the partner, there will be trace or log message.

Variable

Value

aggr-wait-time <200–2000>

Configures the aggregation wait time (in milliseconds) for this port. The default is 2000.

aggregation enable

Enables aggregation on the port, which makes it an aggregated link.

enable

Enables LACP for this port. The default is disabled.

fast-periodic-time <200–20000>

Configures the fast periodic time (in milliseconds) for this port. The default is 1000 ms.

key <1-512|defVal>

Configures the aggregation key for this port.

Enter the aggregation key value or defVal (1024 + IfIndex)

mode {active | passive}

Configures the LACP mode to be active or passive.

partner-key <0–65535>

Configures the partner administrative key.

partner-port <0–65535>

Configures the partner administrative port value.

partner-port-priority <0–65535>

Configures the partner administrative port priority value.

partner-state <0-255 | 0x0-0xff>

Configures the partner administrative state bitmask. Specify the partner administrative state bitmap in the range 0x0–0xff. The bit to state mapping is Exp, Def, Dis, Col, Syn, Agg, Time, and Act.

For example, to set the two partner-state parameters

  • Act = true

  • Agg = true

specify a value of 0x05 (bitmap = 00000101).

partner-system-id <0x00:0x00:0x00:0x00:0x00:0x00>

Configures the partner administrative system ID. Specify a MAC address in the format 0x00:0x00:0x00:0x00:0x00:0x00.

partner-system-priority <0–65535>

Configures the partner administrative system priority value.

priority <0–65535>

Configures the port priority. The default value is 32768. To set this option to the default value, use the default operator with the command.

slow-periodic-time <10000-30000>

Configures the slow periodic time for this port. The default is 30000 ms. To set this option to the default value, use the default operator with the command.

system-priority <0-65535>

Configures the system priority for this port. The default is 32768.

timeout-scale <2-10>

Configures a timeout scale for this port. The default value is 3.

The LACP timeout is equal to the slow periodic time or fast periodic time multiplied by the timeout-scale, depending how you configure the timeout-time variable.

timeout-time {long|short}

Configures the timeout to either long or short.

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