Port Trunking

 

 

 

 

 

 

Trunk Group Operation Using LACP

Table 12-4. LACP Trunk Types

 

 

 

 

 

 

 

 

 

 

 

 

LACP Port Trunk

Operation

 

 

 

 

Configuration

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Dynamic LACP

This option automatically establishes an 802.3ad-complianttrunk group, with LACP for the port Type

 

parameter and DynX for the port Group name, where X is an automatically assigned value from 1 to 24,

 

depending on how many dynamic and static trunks are currently on the switch. (The switch allows a

 

maximum of 24 trunk groups in any combination of static and dynamic trunks.)

 

Note: Dynamic LACP trunks operate only in the default VLAN (unless GVRP is enabled and Forbid is

 

used to prevent the trunked ports from joining the default VLAN). Thus, if an LACP dynamic port

 

forms using ports that are not in the default VLAN, the trunk will automatically move to the default

 

VLAN unless GVRP operation is configured to prevent this from occurring. In some cases, this can

 

create a traffic loop in your network. For more on this topic, refer to “VLANs and Dynamic LACP” on

 

page 12-23.

 

 

 

 

 

Under the following conditions, the switch automatically establishes a dynamic LACP port trunk group

 

and assigns a port Group name:

 

 

 

 

 

• The ports on both ends of each link have compatible mode settings (speed and duplex).

 

• The port on one end of each link must be configured for LACP Active and the port on the other end

 

of the same link must be configured for either LACP Passive or LACP Active. For example:

 

 

 

 

 

 

 

 

 

 

Switch 1

 

 

Switch 2

 

 

 

Port X:

Active-to-Active

 

Port A:

 

 

 

LACP Enable: Active

 

 

LACP Enable: Active

 

 

 

 

 

 

 

 

 

Port Y:

Active-to-Passive

 

Port B:

 

 

 

LACP Enable: Active

 

 

LACP Enable: Passive

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Either of the above link configurations allow a dynamic LACP trunk link.

Backup Links: A maximum of eight operating links are allowed in the trunk, but, with dynamic LACP, you can configure one or more additional (backup) links that the switch automatically activates if a primary link fails. To configure a link as a standby for an existing eight-port dynamic LACP trunk, ensure that the ports in the standby link are configured as either active-to-active or active-to-passive between switches.

Displaying Dynamic LACP Trunk Data: To list the configuration and status for a dynamic LACP trunk, use the CLI show lacp command.

Note: The dynamic trunk is automatically created by the switch, and is not listed in the static trunk listings available in the menu interface or in the CLI show trunk listing.

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