Lenovo Flex System Fabric CN4093 Application Manual page 142

142
CN4093 Application Guide for N/OS 8.2
To avoid the Actor switch ports (with the same admin key) from aggregating in
another trunk group, you can configure a trunk ID. Ports with the same admin key
(although with different LAG IDs) compete to get aggregated in a trunk group.
The LAG ID for the trunk group is decided based on the first port that is
aggregated in the group. Ports with this LAG ID get aggregated and the other ports
are placed in suspended mode. As per the configuration shown in Table
38 gets aggregated first, then the LAG ID of port 38 would be the LAG ID of the
trunk. Port 40 would be placed in suspended mode. When in suspended mode, a
port transmits only LACP data units (LACPDUs) and discards all other traffic.
A port may also be placed in suspended mode for the following reasons:
 When LACP is configured on the port but it stops receiving LACPDUs from the
partner switch.
 When the port has a different LAG ID because of the partner switch MAC being
different. For example: when a switch is connected to two partners.
Trunk ID can be configured using the following command:
CN4093(config)# portchannel <65‐128> lacp key <adminkey of the LAG>
LACP provides for the controlled addition and removal of physical links for the
link aggregation.
Each port in the CN4093 can have one of the following LACP modes.
off (default)

The user can configure this port in to a regular static trunk group.
active

The port is capable of forming an LACP trunk. This port sends LACPDU packets
to partner system ports.
passive

The port is capable of forming an LACP trunk. This port only responds to the
LACPDU packets sent from an LACP active port.
Each active LACP port transmits LACP data units (LACPDUs), while each passive
LACP port listens for LACPDUs. During LACP negotiation, the admin key is
exchanged. The LACP trunk group is enabled as long as the information matches
at both ends of the link. If the admin key value changes for a port at either end of
the link, that port's association with the LACP trunk group is lost.
If an LACP group member port is connected to a port that is in LACP off mode, the
LACP port will not be able to converge and the link goes down.
When the system is initialized, all ports by default are in LACP off mode and are
assigned unique admin keys. To make a group of ports aggregatable, you assign
them all the same admin key. You must set the port's LACP mode to active to activate
LACP negotiation. You can set other port's LACP mode to passive, to reduce the
amount of LACPDU traffic at the initial trunk‐forming stage.
Use the following command to check whether the ports are trunked.
CN4093 # show lacp information
17, if port