Dynamic Lags; Lag Interaction With Other Features - Fujitsu PSWITCH 2048T User Manual

User's Guide
Configured members are added to the LAG (active participation) immediately if the
LAG is configured to be static. There is no wait time before we add the port to the
LAG.
A LAG can be either static or dynamic not both. It cannot have some members
participate in the protocol while other members not participate.

3.1.2.5.2. Dynamic LAGs

Dynamic configuration is supported using the IEEE 802.3ad standard, which is
known as Link Aggregation Control Protocol (LACP).
One advantage of LACP is that the protocol enables the switch to confirm that the
external switch is also configured for link aggregation. When using static
configuration, a cabling or configuration mistake involving the local switch or the
external switch could go undetected and thus cause undesirable network behavior.
Both static and dynamic LAGs (via LACP) can detect physical link failures within the
LAG and continue forwarding traffic through the other connected links within that
same LAG. LACP can also detect switch or port failures that do not result in loss of
link.

3.1.2.5.3. LAG Interaction with Other Features

From a system perspective, a LAG is treated just as a physical port, with the same
configuration parameters for administrative enable/disable, spanning tree port
priority, and path cost as any other physical port.
LAGs and VLANs
When members are added to a LAG, they are removed from all existing VLAN
membership. When members are removed from a LAG, the members rejoin the
VLANs that they were previously members of as per the configuration file.
The LAG interface can be a member of a VLAN complying with IEEE 802.1Q.
LAGs and STP
Spanning tree does not maintain state for members of a LAG. Though spanning
tree does maintain state for the LAG interface. As far as STP is concerned members
of a LAG do not exist. (Internally, the STP state of the LAG interface is replicated for
the member links.)
When members are deleted from a LAG they become normal links and spanning
tree maintains their state information.
December/2018
FUJITSU PSWITCH
57